Showing papers in "Journal of Morphology in 1989"
TL;DR: In some iridescent scales, the reflective elements are contained within the body of the scale and come in two basic forms, lattices that produce diffraction colors (analogous to those produced by opal), and stacks of laminae that produce thin‐film interference colors ( analogous by soap or oil films).
Abstract: Iridescent butterfly scales are structurally colored, relying upon the interaction of light with detailed architecture to produce their color. In some iridescent scales, the reflective elements are contained within the body of the scale and come in two basic forms, lattices that produce diffraction colors (analogous to those produced by opal), and stacks of laminae that produce thin-film interference colors (analogous to those produced by soap or oil films). Both structures are remarkably complex and precise, yet each is only part of the total edifice built by the cell that makes the scale. To understand better how a cell can produce lattices or thin-film laminae, I studied the development of iridescent scales from two lycaenid butterflies. The presence of diffraction and thin-film scales in the same family (and in some cases on the same individual) suggests that the two types must be developmentally related; yet these results yield no clear explanation as to how. The diffraction lattice appears to be shaped within the boundaries of the scale cell by means of a convoluted series of membranes in which the smooth endoplasmic reticulum plays an important part. The thin-film interference laminae appear to result from the condensation of a network of filaments and tubes secreted outside the boundaries of the cell. This paper outlines the developmental histories of both types of scale and discusses the developmental implications of the mechanisms by which they form.
164 citations
TL;DR: Differences were observed between plantarflexors and dorsiflexors, which have architectural features that suit them for force production and excursion respectively, which represented clear morphological distinctions that have functional consequences.
Abstract: The muscle-fiber architecture of 29 muscles from six rabbits (Oryctolagus cuniculus) was measured in order to describe the muscular properties of this cursorial animal, which possesses several specific skeletal adaptations. Several muscles were placed into one of four functional groups: hamstrings, quadriceps, dorsiflexors, or plantarflexors, for statistical comparison of properties between groups. Antagonistic groups (i.e., hamstrings vs. quadriceps or dorsiflexors vs. plantarflexors) demonstrated significant differences in fiber length, fiber length/muscle length ratio, muscle mass, pinnation angle, and number of sarcomeres in series (P less than .02). Discriminant analysis permitted characterization of the "typical" muscle belonging to one of the four groups. The quadriceps were characterized by their large pinnation angles and low fiber length/mass ratios, suggesting a design for force production. Conversely, the hamstrings, with small pinnation angles, appeared to be designed to permit large excursions. Similar differences were observed between plantarflexors and dorsiflexors, which have architectural features that suit them for force production and excursion respectively. Although these differences were not absolute, they represented clear morphological distinctions that have functional consequences.
157 citations
TL;DR: It is confirmed that the semitendinosus muscle of goats contains two separate compartments in series, each with distinct innervation, and the data suggest that the maximum length of muscle fibers may be limited.
Abstract: Morphological and physiological analyses confirm that the semitendinosus muscle of goats contains two separate compartments in series, each with distinct innervation. These compartments of the muscle are in turn composed of short fibers (approximately four fibers in series in the proximal compartment and seven to eight fibers in the distal compartment) which overlap each other for more than 30% of their length, with much of the overlapping portions consisting of slender tails that terminate at one-tenth of the midfiber diameter. Groups of fibers are associated into relatively narrow bands that run end-to-end in each compartment. The data suggest that the maximum length of muscle fibers may be limited; even the fibers of parallel-fibered muscles may not scale with the dimension of the animal.
144 citations
TL;DR: Electromyography and high‐speed cinematography indicate that patterns of muscle activity during feeding and the kinematic movements of opercular rotation and cranial elevation produce a primitive pattern of force and motion input.
Abstract: The feeding mechanism of Epibulus insidiator is unique among fishes, exhibiting the highest degree of jaw protrusion ever described (65% of head length). The functional morphology of the jaw mechanism in Epibulus is analyzed as a case study in the evolution of novel functional systems. The feeding mechanism appears to be driven by unspecialized muscle activity patterns and input forces, that combine with drastically changed bone and ligament morphology to produce extreme jaw protrusion. The primary derived osteological features are the form of the quadrate, interopercle, and elongate premaxilla and lower jaw. Epibulus has a unique vomero-interopercular ligament and enlarged interoperculo-mandibular and pre- maxilla-maxilla ligaments. The structures of the opercle, maxilla, and much of the neurocranium retain a primitive labrid condition. Many cranial muscles in Epibulus also retain a primitive structural condition, including the levator operculi, expaxialis, sternohyoideus, and adductor mandibulae. The generalized perciform suction feed- ing pattern of simultaneous peak cranial elevation, gape, and jaw protrusion followed by hyoid depression is retained in Epibulus. Electromyography and high-speed cinematography indicate that patterns of muscle activity during feeding and the kinematic movements of opercular rotation and cranial elevation produce a primitive pattern of force and motion input. Extreme jaw protrusion is produced from this primitive input pattern by several derived kinematic patterns of modified bones and ligaments. The interopercle, quadrate, and maxilla rotate through angles of about 100 degrees, pushing the lower jaw into a protruded position. Analysis of primitive and derived characters at multide levels of structural and functional organization allows conclusions about the level of design at functional novelties. Epibulus insidiator (Pallas), the sling-jaw wrasse, exhibits an extraordinary ability to pro- trude its jaws during feeding. Epibulus is a monotypic genus in the family Labridae and is widely distributed on coral reefs throughout the tropical Pacific, Indian Ocean, and Red Sea. The extreme protrusion of the mouth of this fish was noted by several early ichthyologists. Renard (1719) refers to Epibulus as Bedreiger (the de- ceiver) and Passer (the thief) and states that this fish "has a long snout hidden in the mouth that it throws out with great agility to capture any prey that comes too close." Bleeker (1862) refers to Epibulus as "ikan kakatua sumpit" (the par- rot wrasse with the pea shooter), and Delsman ('25) cites a Malayan name "tagi utang" (the dunning creditor). These early references reflect interest in the feeding mechanism of Epibulus, which is unique among described fishes. Recent
139 citations
TL;DR: Embryos of Chelydra serpentina were studied during stages of carapace development and tissue morphology, autoradiography, and indirect immunofluorescent localization of adhesion molecules indicate that the outgrowth of the embryonic carapACE occurs as the result of an epithelial–mesenchymal interaction in the body wall.
Abstract: The chelonian carapace is composed of the endochondral ribs and vertebrae associated with a specialized dermis. The ribs are found in an aberrant position compared to those of all other tetrapods; they are superficial and dorsal to the limb girdles. This morphological arrangement, which constitutes the unique chelonian Bauplan, is examined from a developmental perspective. Embryos of Chelydra serpentina were studied during stages of carapace development. Tissue morphology, autoradiography, and indirect immunofluorescent localization of adhesion molecules indicate that the outgrowth of the embryonic carapace occurs as the result of an epithelial–mesenchymal interaction in the body wall. A carapacial ridge composed of mesenchyme of the dermis and overlying ectoderm is formed dorsal to the ectodermal boundary between somitic and lateral plate mesoderm. It is the anlage of the carapace margin, in which the ribs will eventually terminate. The ectoderm of the carapacial ridge is thickened into a pseudostratified columnar epithelium, which overlies a condensation in the mesenchyme of the dermis. Patterns of cell proliferation and the distribution of N-CAM and fibronectin in the carapacial ridge are consistent with patterns seen in other structures initiated by epithelial–mesenchymal interactions such as feathers and limb buds.
Based on an analogy to this developmental mechanism in the development of the limb skeleton, a further analogy with the evolution of the limbs from lateral fin folds is used to form a hypothesis on the evolution of the carapace from elements of the primitive reptilian integument.
128 citations
TL;DR: The architecture of the jaw muscles and their tendons of Alligator mississippiensis is described and their function examined by electromyography.
Abstract: The architecture of the jaw muscles and their tendons of Alligator mississippiensis is described and their function examined by electromyography. Alligator grabs its prey with forward lunges or rapid lateral movements of the head. It does not engage in regular masticatory cycles. Prey is manipulated by inertial movements and the tongue does not appear to play any role in transport. The Mm. adductor mandibulae externus, adductor mandibulae posterior, and pterygoideus activate bilaterally and simultaneously during rapid closing or crushing. The M. pterygoideus does not act during prey holding whereas the Mm. adductor mandibulae externus, adductor mandibulae posterior continue to be active. The Mm. depressor mandibulae and intramandibularis are variably active during both jaw opening and closing.
119 citations
TL;DR: Sperm storage tubules were found in a small region of the posterior portion of the egg albumin‐secreting section of the oviduct located between the infundibulum and the uterus, which is unique among vertebrates.
Abstract: Tubules containing sperm were identified by light microscopy in the oviducts from 11 species of turtles representing six different families. Sperm storage tubules were found in a small region of the posterior portion of the egg albumin-secreting section of the oviduct located between the infundibulum and the uterus. This location of storage tubules, midway between the ovary and vagina, is unique among vertebrates. Ducts, restricted to the posterior albumin region, connect the tubules to the oviduct lumen, allow entrance of sperm to the tubules. Sperm were identified in tubules of female turtles isolated from males for as long as 423 days.
95 citations
TL;DR: It is revealed that ossification of the skull and vertebral column occurs later in S. bombifrons than in other anurans; nonetheless, many aspects of the oSSification sequence seem to be shared by a surprisingly wide range of anuran taxa.
Abstract: The developing skeleton of a pelobatid frog, Spea bombifrons, is described based on a series of 81 cleared-and-stained tadpoles and juveniles. Most limb and limb-girdle elements commence ossification premetamorphically, along with the parasphenoid, frontoparietals, exoccipitals, and vertebral column, during Gosner Stage 36. The chondrocranium undergoes dramatic restructuring at the beginning of metamorphosis (ca. Stage 40); and the nasal cartilages, prootics, premaxillae, nasals, maxillae, septomaxillae, and ischium appear. Near the end of metamorphosis (ca. Stage 44), the branchial arches are resorbed, the hyoid plate and quadrate form, and the angulosplenials, vomers, squamosals, dentaries, and pterygoids ossify. After metamorphosis (Stage 46), the laryngeal cartilages, sternum, omosternum, and plectral apparatus chondrify; and the carpals, tarsals, sphenethmoid, posteromedial hyoid processes, mentomeckelian bones, quadrates, columellae, and opercula ossify. The development of the fused sacrococcygeal articulation in S. bombifrons is described and compared to the more widespread bicondylar articulation. The presumed palatine bone and transverse processes of the coccyx are discussed, as are several seemingly paedomorphic skeletal features of Spea. Comparison with the sequence and timing of ossification in other anurans reveals that ossification of the skull and vertebral column occurs later in S. bombifrons than in other anurans; nonetheless, many aspects of the ossification sequence seem to be shared by a surprisingly wide range of anuran taxa.
88 citations
TL;DR: Plethodontid salamanders have unique nasolabial grooves that may function as “capillary tubes” to convey chemicals to the vomeronasal organ when these animals nose‐tap, and 3H‐proline was placed at the base of these grooves, and autoradiography revealed large concentrations of radioactive material in the vOMS organs.
Abstract: Plethodontid salamanders have unique nasolabial grooves that may function as "capillary tubes" to convey chemicals to the vomeronasal organ when these animals nose-tap. 3 H-proline was placed at the base of these grooves in Plethodon cinereus, and autoradiography revealed large concentrations of radioactive material in the vomeronasal organs. There was no significant accumulation of radioactive material in the main olfactory epithelium. Salamanders with blocked nasolabial grooves lacked significant accumulation of material in their nasolabial grooves or vomeronasal epithelia, although some salamanders had radioactive material in the posterior portion of their vomeronasal organ that had entered through the internal nares. Anteriorly placed vomeronasal organs situated adjacent to the posterior limits of the nasolabial grooves may insure that nose-tapping primarily stimulates the vomeronasal sensory epithelium.
88 citations
TL;DR: Development of the gut into the adult form is protracted over several weeks beyond metamorphosis in steps that may be directly related to the unique postlarval life history of Penaeus setiferus.
Abstract: Ontogeny of the gut in Penaeus setiferus was investigated by reconstruction of serial sections examined by light microscopy. Development of the gut into the adult form is protracted over several weeks beyond metamorphosis in steps that may be directly related to the unique postlarval life history of Penaeus. The gastric mill is lacking in larval stages of P. setiferus. In protozoeal stages Z1 -Z3 , the pyloric ampullae are blind sacs that do not communicate with the midgut. The gland filter first appears in mysis stage M2 . The gastric mill in early postlarval (PL) stages consists of poorly chitinized lobes with flexible setae. By PL21 the ossicles of the gastric mill are rigid and setae are replaced by spine-like denticles, but even by PL35 the gastric mill is neither as massive nor heavily chitinized as in adults. During the mysis stages and early PL stages, the hepatopancreas communicates freely with both the foregut and the midgut trunk. By PL35 the hepatopancreatic ducts are essentially isolated from the remainder of the midgut by foregut ossicles. The midgut in Z1 consists of two pairs of simple caeca and the midgut trunk. During larval growth, each of the lateral midgut caeca develops into a number of lobes. After metamorphosis these lobes begin to ramify into small-diameter tubules, and by PL35 have completely ramified into the hepatopancreas of adults. From M1 to PL4 , the anterior midgut caeca decrease in absolute size and become a single anterior diverticulum. The posterior midgut diverticulum first appears in PL21 as a simple sac and thereafter increases in size and complexity.
84 citations
TL;DR: A study of neuromast ontogeny and lateral line canal formation in Oreochromis aureus and Cichlasoma nigrofasciatum reveals the existence of two classes of neuramasts: those that arise just before hatching and pairs of neurmasts that arise on each lateral line scale lateral to each canal segment at the same time as canal formation.
Abstract: A study of neuromast ontogeny and lateral line canal formation in Oreochromis aureus and Cichlasoma nigrofasciatum reveals the existence of two classes of neuromasts: those that arise just before hatching (presumptive canal neuromasts, dorsal superficial neuromasts, gap neuromasts, and caudal fin neuromasts) and pairs of neuromasts that arise on each lateral line scale lateral to each canal segment at the same time as canal formation. In the anterior trunk canal segment, each presumptive canal neuromast is accompanied by a dorsoventrally oriented superficial neuromast forming an orthogonal neuromast pair. It is suggested that each of these dorsoventrally oriented superficial neuromasts is homologous to the transverse superficial neuromast row described by Munz (Zoomorphology 93:73-86, '79) in other cichlids. It is further suggested that the longitudinal lines described by Munz (Zoomorphology 93:73-86, '79) are derived from the pair of superficial neuromasts that arise during canal formation. Distinct changes in neuromast topography are documented. Neuromast formation, scale formation, and lateral line canal formation are three distinct and sequential processes. The distribution of neuromasts is correlated with myomere configuration; there is always one presumptive canal neuromast on each myomere. A single scale forms beneath each presumptive canal neuromast. Canal segment formation is initiated with the enclosure of each presumptive canal neuromast by an epithelial bridge which later ossifies. The distinction of these three processes raises questions as to the causal relationships among them.
TL;DR: The use of the ruthenium red method for retaining and staining the ECM, with modification of the Luft method for invertebrate embryos, allows for the clarification of certain structures, particularly fiber compaction in the interzonal region, and microvillus‐associated bodies.
Abstract: The extracellular matrix surrounding the sea urchin embryo (outer ECM) contains fibers and granules of various sizes which are organized in recognizable patterns as shown by ultrastructural studies, particularly stereoimaging techniques. The use of the ruthenium red method for retaining and staining the ECM, with modification of the Luft (Anatomical Record 171:347–368, 1971) method for invertebrate embryos, allows for the clarification of certain structures, particularly fiber compaction in the interzonal region, and microvillus-associated bodies.
The inner ECM in the sea urchin embryo includes the basal lamina and blastocoel matrix. Stereoimages show that the fibers which are loosely distributed in the blastocoel matrix become compacted around the periphery of the blastocoel to form the basal lamina.
The ruthenium red method was also used on a number of marine invertebrate embryos and larvae, representing different phyla, to facilitate comparisons between their surface coats. The similarities observed in the specimens shown suggest that ECMs are widely found on marine invertebrate eggs, embryos, and larvae, and that they resemble vertebrate ECMs and may, therefore, have similar functions.
TL;DR: The density and abundance of chloride cells appears to be correlated with the different requirements for osmoregulation in teleost larvae.
Abstract: Distribution and density of the chloride cells in the newly hatched larvae of teleosts vary depending on species and environmental salinity at hatching. In the euryhaline freshwater ayu (Plecoglossus altivelis), chloride cells are concentrated in the skin posterior to the pectoral fins and gradually decrease in number toward the head and tail. In the stenohaline sea water flounder (Kareius bicoloratus), most chloride cells are localized at the inner membrane of gill chambers and in the skin near the openings of gill chambers, but only a few cells appear in the skin of the yolk sac. In the stenohaline freshwater carp (Cyprinus carpio), only a few small chloride cells are scattered in the body skin. The density and abundance of chloride cells appears to be correlated with the different requirements for osmoregulation in teleost larvae.
TL;DR: The Harderian gland of the musk shrew Suncus murinus is elongated anteroposteriorly from in front of the eye to behind the ear, having a poorly developed intraglandular duct system and wide tubular alveoli.
Abstract: The Harderian gland of the musk shrew Suncus murinus is elongated anteroposteriorly from in front of the eye to behind the ear. The gland is divided into two portions: an anterior portion (A portion) and a posterior portion (P portion). The single secretory duct of the gland emerges from the anterior end of the P portion, receives several secretory ducts of the A portion during the course along it, runs around the ventral aspect of the eyeball, and finally opens into the anterior corner of conjunctival sacs. The two portions of the gland show a fundamentally similar histological structure, having a poorly developed intraglandular duct system and wide tubular alveoli. The quantity of lipid vacuoles and stromal connective tissue in the A portion is greater than in the P portion. The lipid vacuoles in both portions are surrounded by unit membranes, but their contents appear different. The lacrimal gland of the musk shrew is located along the ventral side of the P portion of the Harderian gland. The lacrimal duct emerges from its anterior end, runs around the ventral and anterior aspects of the ear, crosses the A portion of the Harderian gland, and finally opens at the posterior corner of conjunctival sacs. The lobules of the lacrimal gland comprise a branched duct system and terminal acini with two types of secretory cells: 1) acidic cells positive both for the periodic acid-Schiff reaction (PAS) and for Alcian blue (AB) and 2) neutral cells positive for PAS and negative for AB. Both cell types tend to make separate acini, but when present in the same acinus, the acidic cells occupy relatively peripheral positions in the acinus. Both cell types lack intercellular canaliculi. On the basis of the present study as well as previous descriptions in the literature, the author suggests that the mammalian lacrimal glands can be divided into two sets: 1) a Glandula lacrimalis superior with multiple secretory ducts associated with the upper eyelid and 2) a Glandula lacrimalis inferior with a single secretory duct opening into the lateral corner of the conjunctival sacs. These glands have a fundamentally similar histological structure; but in the rabbit, which possesses both sets of lacrimal glands, they are different. On the other hand, the secretory cells of lacrimal glands generally have no intercellular secretory canaliculi, which are characteristically present between the serous secretory cells of the salivary glands.
TL;DR: A functional relationship may exist between luteal activity and oviductal secretory activity because the activity of the glandular epithelium varied as gravidity progressed.
Abstract: Morphological changes occurring in the oviduct and epithelial cells of the lizards Crotaphytus collaris and Eumeces obsoletus during the natural reproductive cycle were examined and quantified. Additionally, development of the eggshell at different stages of gravidity was described. The anterior uterus of each species has a distinct glandular type which differs between species: in E. obsoletus, the glands are tubular and in C. collaris, branched saccular. The branched saccular glands in the anterior uterus of C. collaris produce collagen-like material that forms the fibers of the shell membranes. However, fibers from the eggshell of E. obsoletus did not stain for collagen. The shell of both species is composed of a multilayered inner boundary covered externally by fibers of varying thickness. Initial layers are composed of thick fibers all lying along the same general axis. Outer layers of fibers are progressively thinner and an external surface layer composed of glycosaminoglycans (GAGs) is also present. In C. collaris, calcium, which is deposited in relatively small amounts on the shell surface, appears to be secreted by the epithelium of the anterior uterus. The nonciliated secretory epithelial cells covering the villi-like folds of the posterior infundibulum secrete GAGs. Epithelial cell height of the infundibular villi is greatest during early gravidity. A functional relationship may exist between luteal activity and oviductal secretory activity because the activity of the glandular epithelium varied as gravidity progressed.
TL;DR: Light and electron microscopic examination of the dorsal lingual epithelium of beagle dogs (Canis domesticus) revealed three different regions: that anterior to the filiform papillae, that posterior to the papilae, and an interpapillary region.
Abstract: Light and electron microscopic examination of the dorsal lingual epithelium of beagle dogs (Canis domesticus) revealed three different regions: that anterior to the filiform papillae, that posterior to the papillae, and an interpapillary region. Whereas the basal and suprabasal cells are similar throughout, differences characterize the intermediate and surface layers. Keratohyalin granules are common in the intermediate layers in the anterior and interpapillary regions, tonofibrils are prominent in the posterior region, and no keratohyalin granules occur. The surface layer of the interpapillary region is not keratinized, that of the anterior region shows soft keratinization, and that of the posterior region shows hard keratinization. The perimeter of keratohyalin granules is composed of ribosomes 10–20 nm in diameter.
TL;DR: A new mechanical model for function of the pharyngeal jaw apparatus in generalized perciform fishes is developed from work with the family Haemulidae based on anatomical observations, patterns of muscle activity during feeding, and the actions of directly stimulated muscles.
Abstract: A new mechanical model for function of the pharyngeal jaw apparatus in generalized perciform fishes is developed from work with the family Haemulidae. The model is based on anatomical observations, patterns of muscle activity during feeding (electromyography), and the actions of directly stimulated muscles. The primary working stroke of the pharyngeal apparatus involves simultaneous upper jaw depression and retraction against a stabilized and elevating lower jaw. The working stroke is characterized by overlapping activity in most branchial muscles and is resolved into three phases. Four muscles (obliquus dorsalis 3, levator posterior, levator externus 3/4, and obliquus posterior) that act to depress the upper jaws become active in the first phase. Next, the retractor dorsalis, the only upper jaw retracting muscle, becomes active. Finally, there is activity in several muscles (transversus ventrales, pharyngocleithralis externus, pharyngohyoideus, and protractor pectoralis) that attach to the lower jaws. The combined effect of these muscles is to elevate and stabilize the lower jaws against the depressing and retracting upper jaws. The model identifies a novel mechanism of upper jaw depression, here proposed to be the primary component of the perciform pharyngeal jaw bite. The key to this mechanism is the joint between the epibranchial and toothed pharyngobranchial of arches 3 and 4. Dorsal rotation of epibranchials 3 and 4 about the insertion of the obliquus posterior depresses the lateral border of pharyngobranchials 3 and 4 (upper jaw). The obliquus dorsalis 3 muscle crosses the epibranchial-pharyngo-branchial joint in arches 3 and 4, and several additional muscles effect epibranchial rotation. Five upper jaw muscles cause upper jaw depression upon electrical stimulation: the obliquus dorsalis 3, levator posterior, levator externus 3/4, obliquus posterior, and transversus dorsalis. This result directly contradicts previous interpretations of function for the first three muscles. The presence of strong depression of the upper pharyngeal jaws explains the ability of many generalized perciform fishes to crush hard prey in their pharyngeal apparatus.
TL;DR: The internal anatomy of juveniles and adults of Hypochthonius rufulus selected as a model species representing the lower Oribatida was investigated histologically and compared with the published characteristics of higher oribatid internal anatomy.
Abstract: The internal anatomy of juveniles and adults of Hypochthonius rufulus selected as a model species representing the lower Oribatida was investigated histologically and compared with the published characteristics of higher oribatid internal anatomy. In this species, the cuticle is weak and flexible, consisting of epicuticle and endocuticle on the body, but including an exocuticle between the epicuticle and endocuticle of the legs. Walls of the mesenteron in the digestive tract are of uniform thickness and structure without any regional thickening, and there are no proventricular glands. The hindgut is apparently divided into five parts: colon 1 and 2, rectum 1 and 2, and anal atrium; food bolus exhibits a multilamellar structure in this section. The glandular system is less diversified than in some other oribatids. Tracheae are apparently lacking. Females possess only two relatively large eggs, filling one-half of opistosoma, and they lack ovipositors. Eggs are present in females during the whole year. Gonad buds appear first in the protonymph stage. Only one male was found among 146 adults studied. No male external organ (aedeagus or penis) is present.
TL;DR: This model generates numerous testable predictions about tongue function and provides a mechanistic basis for the hypothesis that tongue projection in salamanders evolved from primitive intraoral manipulative action of the hyobranchial apparatus.
Abstract: The projectile tongue of caudate amphibians has been studied from many perspectives, yet a quantitative kinetic model of tongue function has not yet been presented for generalized (nonplethodontid) terrestrial salamanders The purposes of this paper are to describe quantitatively the kinnematics of the feeding mechanism and to present a kinetic model for the function of the tongue in the ambystomatid salamander Ambystoma tigrinum Six kinematic variables were quantified from high-speed films of adult A tigrinum feeding on land and in the water Tongue protrusion reaches its maximum during peak gape, while peak tongue height is reached earlier, 15 ms after the mouth starts to open Tongue kinematics change considerably during feeding in the water, and the tongue is not protruded past the plane of the gape Electrical stimulation of the major tongue muscles showed that tongue projection in A tigrinum is the combined result of activity in four muscles: the geniohyoideus, Subarcualis rectus 1, intermandibularis posterior, and interhyoideus Stimulation of the Subarcualis rectus 1 alone does not cause tongue projection The kinetic model produced from the kinematic and stimulation data involves both a dorsal vector (the resultant of the Subarcualis rectus 1, intermandibularis posterior, and interhyoideus) and a ventral vector (the geniohyoideus muscle), which sum to produce a resultant anterior vector that directs tongue motion out of the mouth and toward the prey This model generates numerous testable predictions about tongue function and provides a mechanistic basis for the hypothesis that tongue projection in salamanders evolved from primitive intraoral manipulative action of the hyobranchial apparatus
TL;DR: 3H‐Thymidine incorporation experiments in Barbus conchonius showed that presumptive primordial germ cells (PGCs) terminated their mitotic activity between midepibolys, and late epiboly, and thereafter, rapid proliferation began.
Abstract: 3 H-Thymidine incorporation experiments in Barbus conchonius showed that presumptive primordial germ cells (PGCs) terminated their mitotic activity between midepibolys, and late epiboly At the ten-somite stage, shortly after labeling of PGCs by uptake of 3 H-thymidine became arrested, they could be recognized by their relatively large size and large nucleus They were located in two longitudinal rows of cells between mesoderm and periblast, always at the same distance to the left and right of the notochord Contact with the endoderm was not observed before the 16- to 23-somite stage The numbers of PGCs were small (mean number, 18-19) and remained small for nearly 3 weeks Mitotic activity was not observed in PGCs during that period; thereafter, rapid proliferation began There is no evidence for active migration of PGCs; it is assumed that they are merely translocated passively together with their surrounding tissues No specific constituents were detected with histochemical methods for glycogen, alkaline phosphatase, and RNA Electron microscopy revealed the presence of "nuage" around the nucleus of PGCs This material corresponded with perinuclear dense bodies as seen with light microscopy from the 19-somite stage onward It is concluded that presumptive PGCs segregate from the somatic cells between midepiboly and late epiboly, before the three germ layers have been formed, and that locations of PGCs in the endodermal or mesodermal layer may be merely transitory stages during their translocation toward the gonadal primordia
TL;DR: It is suggested that the physiological basis for the need for turning lies in maximizing the growth rate of the area vasculosa to maximize yolk use and embryonic growth rate.
Abstract: Effect of turning of the egg during incubation on development of the area vasculosa of the chick embryo was investigated. The size of the area vasculosa was determined by two methods: direct measurement with calipers and measurement of a template cut from the eggshell by use of an automatic surface area recorder. The effects of turning and additionally the effects of lowered temperature (36°C) on both growth of the area vasculosa by day 7 and embryo growth by day 14 of incubation were investigated. The effects of turning during a critical period for turning, from 3 to 7 days of incubation, were also recorded. Generally, failure to turn eggs retarded growth of the area vasculosa. Turning during the critical period stimulated the extent of growth of the area vasculosa by day 7 of incubation and of subsequent embryonic growth by day 14. Incubation at low temperature resulted both in reduced expansion of the area vasculosa and retarded embryonic growth in a pattern similar to that observed for unturned eggs. It is suggested that turning stimulates development of blood vessels in the area vasculosa via localized increases in blood pressure. The effect of a reduced area vasculosa is considered to retard embryonic development through restricted nutrient uptake from the yolk. The prevailing hypothesis that turning prevents deleterious membrane adhesions is questioned in light of these observations. It is suggested that the physiological basis for the need for turning lies in maximizing the growth rate of the area vasculosa to maximize yolk use and embryonic growth rate.
TL;DR: The sequence of morphological differentiation of Müller cells in the chick retina was investigated in relation to the differentiation of the retinal neurons using the Golgi method.
Abstract: The sequence of morphological differentiation of Muller cells in the chick retina was investigated in relation to the differentiation of the retinal neurons using the Golgi method. From the beginning of differentiation, the Muller cell develops spurs and lateral processes. Some of these glial processes become transformed into accessory prolongations of the Muller cell. From the 17th or 18th day of incubation, the morphology of the Muller cells is similar to that of the adult retina. On the basis of their inner prolongation, two types of Muller cells were identified. The first type, with diffuse and abundant descending processes, is identical to that described classically. The second type is a cell characterized by sparse and scanty inner ramifications.
This report also describes electron microscopic observations of Muller cells and their enwrapping relationship with the axons of the optic nerve fiber layer.
TL;DR: The simultaneous use of electromyography, strain gauges, and cinematography show that the capacity of continuous displacement from a single peg is based on the following: sequential activity of the tested muscles from front to rear.
Abstract: The simultaneous use of electromyography (EMG), strain gauges, and cinematography show that the capacity of continuous displacement from a single peg is based on the following: sequential activity of the tested muscles from front to rear; activity restricted to the short portion of the body in contact with the peg; alternate action of the muscle longissimus dorsi on the two sides, the transition between one side to the other occurring at the site of contact with the peg; unilateral activity of the muscle supracostalis ventralis responsible for a bulging against the peg; a great stability in the direction of the resultant force, which makes only a small angle with the directio of the motion.
TL;DR: The TBA is a novel complex feature of the head that characterizes osteoglossomorph fishes and provides a case study in the origin of novel functions and roles in the vertebrate musculoskeletal system.
Abstract: Osteoglossomorph fishes are characterized by having three sets of jaws: a mandibular jaw apparatus (MJA) anteriorly, a pharyngeal jaw apparatus (PJA) posteriorly, and a tongue-bite apparatus (TBA) associated with basihyal and parasphenoid teeth. The TBA is a novel complex feature of the head that characterizes osteoglossomorph fishes and provides a case study in the origin of novel functions and roles in the vertebrate musculoskeletal system.
The function of the tongue-bite in the osteoglossomorph fish Notopterus was characterized by using high-speed cinematography and electromyography. The tongue-bite is used during intraoral prey processing to shred and disable prey. Two distinct uses of the TBA were defined on the basis of kinematic and electromyographic profiles: raking and open-mouth chewing. During raking behavior, the prey is held fixed in the MJA, the neurocranium is elevated, and the pectoral girdle is retracted. The adductor mandibulae, hypaxialis, epaxialis, and posterior intermandibularis muscles are all highly active, but only very low activity is observed in the sternohyoideus muscle. During open-mouth chewing behavior, the prey is located within the oral cavity, posterior pectoral girdle rotation is less than during raking, and the levator operculi muscle shows relatively high activity.
We propose that a shearing action of the basihyal (moved anteroposteriorly by the posterior intermandibularis and hypaxial muscles) with respect to the neurocranium (elevated by epaxial muscles) is the critical aspect of the tongue-bite in Notopterus. The body muscles (epaxials and hypaxials) provide the main power for the tongue-bite. We hypothesize that lack of sternohyoideus activity during intraoral prey processing, posterior pectoral girdle rotation, and a long-fibered posterior intermandibularis muscle are novel structures associated with the tongue-bite apparatus within osteoglossomorph fishes.
TL;DR: The frog‐eating bat (Trachops cirrhosus) is unusual among bats studied because of its reliance on low‐frequency (<5 kHz) sounds emitted by frogs for prey localization, and the ear of this bat is investigated in order to identify anatomical features that might serve as adaptations for low-frequency hearing.
Abstract: The frog-eating bat (Trachops cirrhosus) is unusual among bats studied because of its reliance on low-frequency (<5 kHz) sounds emitted by frogs for prey localization. We investigated the ear of this bat in order to identify anatomical features that might serve as adaptations for low-frequency hearing. Trachops cirrhosus has a variety of anatomical features that might enhance low-frequency hearing, either by increasing sensitivity to low-frequency sounds or expanding the total frequency range to include lower frequencies. These bats have long pinnae, and a long and wide basilar membrane. The basal portion of the basilar membrane is much stiffer than the apical portion, and the basal portion of the tectorial membrane is more massive than the apical portion. There is also a concentration of mass in the apical portion of the cochlea. T. cirrhosus possesses the largest number of cochlear neurons reported for any mammal, the second highest density of cochlear neurons innervation known among mammals, and three peaks of cochlear neuron density. Other bats have two peaks of cochlear neuron density, lacking the apical concentration, while other mammals usually have only one. T. cirrhosus differs from most other small mammals and bats in characteristics of the apical portion of the cochlea, i.e., that area where the place theory of hearing predicts that low frequencies are detected.
TL;DR: Ten (or possibly eleven) features are identified as being influenced by heterochrony within Uperoleia, confirming that the genus represents a highly pedomorphic lineage, four elements are influenced by heterogeneity in Crinia, but only two in Pseudophryne.
Abstract: Descriptive data are provided for ontogeny of bone to metamorphosis in the myobatrachine species Uperoleia trachyderma; in pre- and postmetamorphic specimens of U. lithomoda, Crinia signifera, and Pseudophryne bibroni; and in postmetamorphic specimens of U. laevigata. Data derived from postmetamorphic U. laevigata indicate that dermal and endochondral elements ossify independently of each other in Uperoleia. Crinia signifera does not show the same degree of independence of ossification of dermal and endochondral elements as Uperoleia, whereas dermal and endochondral elements are not independent in P. bibroni. Ten (or possibly eleven) features are identified as being influenced by heterochrony within Uperoleia, confirming that the genus represents a highly pedomorphic lineage, four elements are influenced by heterochrony in Crinia, but only two in Pseudophryne.
TL;DR: A pattern with highly homogeneous orders that clearly differ in their anatomic and cytologic features is found, which does not support the hypothesis of a common origin of the “keratose” sponges.
Abstract: The aquiferous system of representatives of the orders Dictyocer-atida, Dendroceratida, and Verongida has been studied to note its relevance to the systematics of the groups. The volume of the choanocyte chamber, the size and shape of the choanocytes, the number of choanocytes per chamber, the relative development of the mesohyl, and the features of endopinacocytes are estimated from scanning and transmission electron microscopic observations of representatives of most families of the three orders. Although the Dysideidae have a reticulate skeleton and were classified in the order Dictyoceratida, they are actually closer to the Aplysillidae (Dendroceratida) than to dictyoceratids. The anatomy and cytology of the Halisarcidae differ profoundly from those of these three orders and are clearly more closely related to nonkeratose sponges. Some changes in classification lead to a pattern with highly homogeneous orders that clearly differ in their anatomic and cytologic features, which does not support the hypothesis of a common origin of the “keratose” sponges.
TL;DR: With increasing age and developmental state of the tissues, radiolabeled and stained dermatan sulfate and heparan sulfates progressively increase in relative quantity compared to chondroitin sulfate both in muscle and in associated connective tissue elements.
Abstract: The leg musculature from 11, 14, and 17 day chick embryos was analyzed histochemically to investigate the temporal and spatial distribution of various types of sulfated glycosaminoglycans present during skeletal muscle development. Types of glycans were identified by selective degradation with specific glycosidases and nitrous acid coupled with Alcian blue staining procedures for sulfated polyanions and with [35S]sulfate autoradiography. On day 11, radiolabeled chondroitin sulfate glycosaminoglycans are localized extracellularly in both the myogenic and connective tissue cell populations. By day 17, incorporation of [35S]sulfate into chondroitin sulfate is substantially reduced, although Alcian blue-stained chondroitin sulfate molecules are still detectable. With increasing age and developmental state of the tissues, radiolabeled and stained dermatan sulfate and heparan sulfate progressively increase in relative quantity compared to chondroitin sulfate both in muscle and in associated connective tissue elements. These changes in glycosaminoglycans correlate well with similar changes previously determined biochemically and further document the alterations in extracellular matrix components during embryonic skeletal myogenesis.
TL;DR: More hair cells are found within the same calyx in birds than described in previously examined reptile and mammalian species.
Abstract: The utricular macula was examined in 20 bird species belonging to 13 families. Two types of hair cells, a bouton-innervated and a calyceal hair cell, were found. The calyceal hair cells are found situated in two zones that follow the anterior and lateral borders of the utricular macula in all except two species. In the rhea and mute swan, only one zone was found, corresponding to the inner zone of the other species. The majority of calyceal hair cells are present in the anterior and lateroposterior part of the inner zone. They are often gathered in a common calyx. More hair cells are found within the same calyx in birds than described in previously examined reptile and mammalian species. In nine specimens of four species belonging to four different families, the calyceal hair cells constitute between 7 and 12% of the total number of hair cells, which varies from about 20,000 to 40,000.
TL;DR: Diaphragmatic architecture, histochemistry, and end‐plate distribution were examined by use of a combination of anatomical methods, including fiber microdissections, cholinesterase staining, and enzyme histochemistry to validate and extend the previous work.
Abstract: Previous anatomical descriptions of the diaphragm have contained several contradictory findings. To validate and extend the previous work, diaphragmatic architecture, histochemistry, and end-plate distribution were examined by use of a combination of anatomical methods, including fiber microdissections, cholinesterase staining, and enzyme histochemistry. Microdissections showed that muscle-fiber fascicles throughout the diaphragm contain both long fibers that run from origin to insertion and shorter fibers with intrafascicular terminations. Fibers with intrafascicular terminations were particularly common in the costal diaphragm, where they accounted for the majority of sampled fibers. The heterogeneity of fiber length was reflected in the pattern of end-plate banding. Cholinesterase studies showed that fiber fascicles in cat and kitten diaphragms were crossed by two to four end-plate bands distributed in discontinuous arrays across the width of the muscle. A similar pattern of multiple banding was also demonstrated in the adult and neonatal dog. However, rat and rabbit diaphragms had only a single, continuous end-plate band. Histochemical studies of fiber types in different parts of the feline diaphragm showed that costal, crural, and sternal subregions had similar overall proportions of fiber types. However, type SO (slow oxidative) fibers were distributed more densely on the thoracic than the abdominal surface of costal and crural, but not sternal subregions. Type SO fibers were also concentrated in fiber fascicles bordering the esophageal hiatus.