Showing papers in "Cell and Tissue Research in 1976"
TL;DR: Latent β-glucuronidase and glucosaminidase activities have been demonstrated in small cytoplasmic particles, which may possibly be primary lysosomes, as well as some larger granules of the digestive cells of the common mussel, indicating that the stress response involved changes in structure and function of membranes.
Abstract: Latent beta-glucuronidase and glucosaminidase activities have been demonstrated in small cytoplasmic particles, which may possibly be primary lysosomes, as well as some larger granules of the digestive cells of the common mussel. Latency was indicated by increased staining of these structures following incubation in buffer at pH 4.5 at 37 degrees C. The exposure of mussels to temperatures of 25-28 degrees C over a period of four days induced a significant decrease in the latency of lysosomal glucosaminidase. Thermal death produced labilization of lysosomes although selective release of hydrolase activity was indicated by the differential latency of glucosaminidase and glucuronidase. The injection of hydrocortisone induced a significant increase in latency in stressed animals, indicating that the stress response involved changes in structure and function of membranes.
238 citations
TL;DR: Pit cells are situated in the wall of rat liver sinusoids, and have hyaloplasmic pseudopodia intermingling with the microvilli of the parenchymal cells, and contain highly characteristic granules.
Abstract: Pit cells--a new type of cell first described here and so named because they contain highly characteristic granules--are situated in the wall of rat liver sinusoids, and have hyaloplasmic pseudopodia intermingling with the microvilli of the parenchymal cells. The characteristic granules are mainly situated at one side of the nucleus, the other side showing organelle-free hyaloplasm. Pit cells are also found in portal tracts and in granuloma-like cellular aggregates. They also occur in rat peripheral blood, although there are morphological differences between cells in these two sites. Pit cells can be regarded as regular inhabitants of the sinusoidal wall, and therefore belong to the series of sinusoidal cells, i.e., the endothelial (Wisse, 1972), Kupffer (Widmann et al., 1972; Wisse and Daems, 1970; Wisse, 1974a, b), and fat-storing cells (Ito, 1973). Pit cells do not phagocytose and do not react to a great number of experimental conditions, to which endothelial and Kupffer cells do react (Wisse, 1972, 1974b). Mitosis has been observed in a pit cell. The function of pit cells remains obscure, but an endocrine function is suggested by the morphology of their highly characteristic granules.
187 citations
TL;DR: Changes in the thecal microcirculation may play a key role in atresia: adjacent to the basal lamina of non-atretic follicles, there is a well-developed capillary network which is significantly reduced as atresian progresses.
Abstract: The structural changes that characterize primary, secondary and tertiary atresia in sheep Graafian follicles have been studied by means of histological, histochemical and ultrastructural techniques. In primary atresia vacuoles representing swollen endoplasmic reticulum are prominent along the antral border together with disorganized granulosa cells containing pyknotic nuclei. Phagocytic cells, which increase in number as atresia progresses, were seen within the membrana granulosa and are considered to be transformed granulosa cells. Even in follicles classified as nonatretic, a few antral vacuoles and occasional pyknotic nuclei are present. During secondary atresia there is a large increase in the number of cells with pyknotic nuclei; many of these nuclei had been extruded and had fused to form the characteristic Feulgen-positive atretic bodies found along the edge of the antral cavity. These bodies usually have a diameter of up to 15 μm but occasionally reached as much as 400 μm. A second area of degeneration is frequently present in the membrana granulosa, two or three cell layers from the basal lamina, and it is at this level that exfoliation of granulosa cells occurs in tertiary atresia. In contrast to the membrana granulosa, there are during secondary atresia, only slight indications of degeneration in the cumulus. In tertiary atresia the membrana granulosa is highly disorganized; the atretic bodies are often fewer in number than at earlier stages. The basal lamina remains essentially intact. It is at this stage that the first clear signs of degeneration occur in the theca interna. Despite some disintegration of the cumulus, the integrity of the oocyte is maintained and its nucleus remains vesicular. Changes in the thecal microcirculation may play a key role in atresia: adjacent to the basal lamina of non-atretic follicles, there is a well-developed capillary network which is significantly reduced as atresia progresses.
165 citations
TL;DR: It was shown that the cytoplasmic AM fibrils are arranged as bundles of highly parallel F-actin filaments, which can be assumed to represent structures essential for motive force generation in contraction processes in non-muscle cells.
Abstract: A special cell line derived from a rat mammary adenocarcinoma (RMCD cells) displays a distinct pattern of actomyosin fibrils (AM fibrils) visible with phase contrast, Nomarski interference and polarized light optics. It was shown that the cytoplasmic AM fibrils are arranged as bundles of highly parallel F-actin filaments. The chemical nature of the filaments was identified by incubation with heavy meromyosin from rabbit skeletal muscle. These cytoplasmic actomyosin fibrils actively contract under isotonic conditions. This was shown by contraction experiments under polarized light optics, by cinematographic analysis and by direct proof of the contractility of AM fibrils isolated by laser micro-dissection. Thus, cytoplasmic AM fibrils can be assumed to represent structures essential for motive force generation in contraction processes in non-muscle cells.
163 citations
TL;DR: Special neurons accumulating indoleamines have been detected in the retina of rabbit, cat and goldfish and do not correspond to the previously known dopaminergic retinal neurons, which can be demonstrated with a specially developed technique, simultaneously with the indoleamine-accumulating neurons.
Abstract: Special neurons accumulating indoleamines have been detected in the retina of rabbit, cat and goldfish. They have their perikarya in the inner-most cell row of the inner nuclear layer, among the amacrine cells, and send their processes to various parts of the inner plexiform layer. The distribution of the processes is different in the different animals investigated. The neurons do not correspond to the previously known dopaminergic retinal neurons, which have a different distribution of their terminals and which can be demonstrated with a specially developed technique, simultaneously with the indoleamine-accumulating neurons.
140 citations
TL;DR: Freeze-etched rhabdoms and adjacent cytoplasmic organelles from crayfish compound eyes have been studied for evidence of photoreceptor membrane cycling andMembrane leaflet orientations show that primary endocytosis from microvilli must be followed by secondary endocyTosis of fused coated vesicles to form MVB.
Abstract: Freeze-etched rhabdoms and adjacent cytoplasmic cytoplasmic organelles from crayfish compound eyes have been studied for evidence of photoreceptor membrane cycling. The protoplasmic leaflet face (PF) of split photoreceptor membrane of the microvilli is richly particulate. The particles (92 +/- 16 A in diameter in surface fractures; 70 +/- 9 A in cross fractures; density about 8000/mum2) probably indicate rhodopsin molecule localization. Closely similar particles appear in membranes of pinocytotic vesicles, multivesicular bodies (MVB) and secondary lysosomes. In contrast other retinular cell membranes like plasma membrane remote from the rhabdom are quite distinct (60 +/- 23 A particle diameter, density ca 1000/mum2.) Histochemical tests for acid phosphatase demonstrate its presence in well-developed (but not early stage) MVBs, mixed lamellar vesicular bodies (LVB) and lamellar bodies. Density of PF particles decreases from 8000 in MVB to roughly 4500/mum2 in LVB indicating a degradative sequence from rhabdom to lamellar bodies. Membrane leaflet orientations show that primary endocytosis from microvilli must be followed by secondary endocytosis of fused coated vesicles to form MVB. Morphological evidence for photoreceptor membrane resynthesis has not been found yet in crayfish but some has been obtained in other crustaceans.
118 citations
TL;DR: In serial sections septa of connective tissue and groups of muscle cells were found to disappear within few tens of microns or to merge with other septa, and the taenia did not appear to be divided into clear-cut muscle cell bundles.
Abstract: A quantitative study of muscle cells of the guinea-pig taenia coli is reported. Stereological methods were used on electron micrographs and phase contrast micrographs. Smooth muscle cells of taeniae fixed under 1 gram load were about 515 μm long. Muscle cell volume was about 3,500 μm3 and cell surface 5,300 μm2. About 168,000 caveolae were found at the surface of each muscle cell, covering about 29 percent of its surface. They produced a 73 percent increase of the cell membrane compared to a smooth-surfaced cell. The ratio surface-to-volume is about 1∶0.67 if the geometrical surface is considered, or 1∶0.39 if the total surface of the cell membrane (including the caveolae) is considered. Mitochondria constituted 3.5–4 percent of the cell volume. A few nexuses were observed, both between two muscle cells and between a muscle cell and an interstitial cell. In serial sections septa of connective tissue and groups of muscle cells were found to disappear within few tens of microns or to merge with other septa, and the taenia did not appear to be divided into clear-cut muscle cell bundles. Bundles of smooth muscle cells were seen passing from the taenia to the underlying circular muscle. The transverse sectional area of the taenia ranged between 0.14 and 0.39 mm2; it showed about 526 blood vessels · mm-2.
118 citations
TL;DR: It was demonstrated that, in the amphibian magnocellular hypothalamo-hypophysial neurosecretory system, vasotocin and mesotOCin are synthesized in separate neurons, and a tendency to preferential location of the two kinds of neuronal perikarya is described.
Abstract: Using the unlabeled antibody peroxidase-antiperoxidase (PAP) technique at the light microscopic level, it was demonstrated that, in the amphibian magnocellular hypothalamo-hypophysial neurosecretory system, vasotocin and mesotocin are synthesized in separate neurons. A tendency to preferential location of the two kinds of neuronal perikarya is described. The neurosecretory perikarya are the origin of separate vasotocinergic and mesotocinergic axons. In the neural lobe, the pattern of distribution of the two types of axons is different. The coarse ventricular “dendrites” of both kinds of neurons are hormone-containing processes. Staining with anti-bovine neurophysin I serum suggested that the vasotocinergic and the mesotocinergic neurons synthesize different neurophysins.
115 citations
TL;DR: Dry-mount autoradiography was combined with peroxidase immunocytochemistry to examine estrogen uptake in four pituitary cell types and found that long-term ovariectomy caused a significant increase in estrogen uptake of gonadotropes, somatotropes and lactotropes while uptake in thyrotropes decreased.
Abstract: Dry-mount autoradiography was combined with peroxidase immunocytochemistry to examine estrogen uptake in four pituitary cell types. Quantification by silver grain counts was used to compare 3H-estradiol uptake in nuclei of pituitary cells 60 min after i.v. injection into short-term (control) and long-term ovariectomized and in long-term thyroidectomized rats. Under all three hormonal states, the order of labeling intensity was: gonadotropes > somatotropes > lactotropes > thyrotropes. Long-term ovariectomy caused a significant increase in estrogen uptake of gonadotropes, somatotropes and lactotropes, while uptake in thyrotropes decreased. Long-term thyroidectomy decreased uptake in somatotropes, lactotropes and thyrotropes while gonadotropes remained unchanged.
110 citations
TL;DR: Changes in spatial distribution of the labelled cells and in labelling indices of each cell line in the gastric glands were studied at various days after 3H-thymidine injections, and the fate of the mucous neck cell, the replacement of the chief cell and the mode of cell migration were discussed.
Abstract: Ten hamsters received repeated injections of 3H-thymidine for 4 days and were allowed to survive for 7, 28, 42 and 100 days. Changes in spatial distribution of the labelled cells and in labelling indices of each cell line in the gastric glands were studied at various days after 3H-thymidine injections, and the fate of the mucous neck cell, the replacement of the chief cell and the mode of cell migration were discussed.
110 citations
TL;DR: Cytological evidence supports the hypothesis that the perineural endothelium provides a relatively tight and highly selective barrier separating the peripheral nerves from surrounding tissue and its extracellular fluid spaces.
Abstract: Fine strands of motor nerves were examined with the electron microscope using thin section as well as freeze-etching techniques. The specimens were taken from frog cutaneous pectoris nerve, rat sciatic nerve, mouse and shrew phrenic nerves and from human skin nerves. The perineural sheath (Henle, Ranvier, Key and Retzius) consists of one to several concentric laminae of endothelial cells; it encases nerve fascicles and eventually individual nerve fibers and terminals. The endothelial cells are extremely thin and fitted together smoothly by overlap and dove-tailing of their border zones. The cell contacts are formed by continuous zonulae occludentes, often reinforced by maculae adhaerentes, and in depth they comprise 3–15 strands with an average of 5–6 strands per junction. The membranes of endothelial cells are studded with attachment sites and stomata of plasmalemmal vesicles suggesting a high level of pinocytotic activity. This phenomenon is by no means restricted to the external laminae of the endothelial sheath. Each endothelial lamina is vested with basement membranes on both (epineural and endoneural) sides, and the spaces between laminae contain a few collagen fibers and fibroblasts. Occasionally, punctate tight junctions are seen between laminae. Cytological evidence supports the hypothesis that the perineural endothelium provides a relatively tight and highly selective barrier separating the peripheral nerves from surrounding tissue and its extracellular fluid spaces. This effect is achieved on the one hand by the sealing of pericellular spaces and on the other hand by a membrane controlled transcellular transport mechanism (pinocytosis), both of which are enhanced by their serial arrangement.
TL;DR: The accuracy of the structural pattern displayed by the giant units in the lobular plate seems to suggest that this optic ganglion represents the ultimate orderly projection of the external world in the brain of the fly.
Abstract: An anatomical investigation has been carried out on the third optic ganglion of the fly, Musca domestica. Two systems of giant units, the dendritic arborizations of which are arranged orthogonally relative to each other, dominate the neuropile of this ganglion. The elements of the two systems have been reconstructed using a graphical procedure based on histological sections. One system branches predominantly in the dorsoventral direction, the other one in the anterior-posterior direction. Both systems of the giant units have a twin system composed of elements smaller in diameter and strictly parallel to the main units. The two systems have been termed the Vertical and Horizontal Systems. The elements of the two systems of fibers project into the periesophageal region where they come into contact with other descending elements. Electron microscopic investigations show that the two systems are post-synaptic at the level of the ganglion from which they originate. The horizontal system has been shown to be post and pre-synaptic in nature during its course in the mid-brain and ultimately presynaptic at its endings in the periesophageal ring. The peculiar geometric arrangement of the two anatomical systems of fibers suggests a precise function in relation to the visual world and in particular to the detection of the direction of motion. The accuracy of the structural pattern displayed by the giant units in the lobular plate seems to suggest that this optic ganglion represents the ultimate orderly projection of the external world in the brain of the fly. A short review of the electrophysiological data concerning this ganglion has been tentatively correlated with some behavioral data related to the visual orientation and fixation in insects.
TL;DR: Two main morphological patterns are significant for the organization of the retina during neurogenesis: the cell to cell contacts of migrating cells and the spatial arrangement of Müller cells which could provide guidelines for migration of neuronal elements.
Abstract: Fixed retinae of chick embryos and chicks of the first week after hatching were fractured and examined with the scanning electron microscope. The matrix cells of the retina proliferate up to the beginning of the second week. The migrating cells are oriented in cell cords. This columnar organizaion prevails up to the development of the plexiform layers formed as a consequence of the outgrowth of the dendritic and axonal cell processes. Special attention was paid to the differentiation of the ganglion, bipolar and receptor cells, and the radial fibers (Muller cells). Two main morphological patterns are significant for the organization of the retina during neurogenesis: a)the cell to cell contacts of migrating cells and b)the spatial arrangement of Muller cells which could provide guidelines for migration of neuronal elements.
TL;DR: The taste buds from fungiform papillae and the hard palate of frogs were investigated with the scanning and transmission electron microscopes and the occurrence of two types of receptors explains physiological results.
Abstract: The taste buds from fungiform papillae and the hard palate of frogs were investigated with the scanning and transmission electron microscopes. An immature pre-taste cell and a mature taste cell can be differentiated. Only the mature taste cell exhibits synaptic contact with the afferent taste fibre. Glandular and satellite supporting cells envelop the thin apical processes of the sensory cells. At the base of the taste disc up to 10 Merkel cells form a complex with nerve endings. There are two types of myelinated fibres, large and small. The small fibre innervates the taste cells, the thicker nerve fibre the Merkel cells. The occurrence of two types of receptors explains physiological results.
TL;DR: Within the low viscous flowing endoplasm of Physarum polycephalum a considerable amount of actin is in the non-filamentous state, which can be demonstrated by applying poly-L-lysin to surface spreads of native protoplasm.
Abstract: (1) Within the low viscous flowing endoplasm of Physarum polycephalum a considerable amount of actin is in the non-filamentous state. This can be demonstrated by applying poly-L-lysin to surface spreads of native protoplasm. (2) It has been shown that in protoplasmic drops the endoplasm-ectoplasm transformation is accompanied by an actin polymerization from the non-filamentous state to F-actin. (3) The actual state of the labile G-F-actin equilibrium determines the varying consistency (viscosity) of the cytoplasm. (4) Increasing viscosity can be interpreted as being brought about by a) shifting of the G-F-actin equilibrium to the filamentous side, and (b) increased myosin-mediated binding sites between actin filaments. (5) Polymerization and depolymerization processes are involved in the rhythmically occurring contraction-relaxation cycle of cytoplasmic actomyosin in Physarum. (6) Cytoplasmic actin and myosin represent the architectural proteins of the contractile gel reticulum in eukaryotic cells. (7) The importance of the regulation of actin polymerization as a basic control mechanism of the eukaryotic cell is discussed.
TL;DR: The observation favours the assumption that NGF is derived from a precursor molecule and that the precursor is transformed into immunologically active NGF within the secretory granules during their transport from the basal to the apical part of the tubular cells.
Abstract: Nerve growth factor (NGF) was localized in the submandibular gland of adult male mice by a direct immunocytochemical method using highly purified antibodies against NGF coupled to horseradish peroxidase. In light microscopic sections the reaction product was entirely confined to the cells of the secretory tubules. The acinar part of the gland was free of reaction product. This finding was confirmed by electron microscopy. Within the cells NGF was localized exclusively in the apical secretory granules. No reaction was observed in the rough endoplasmic reticulum, the Golgi region or in the granules of the basal part of the cells. This observation favours the assumption that NGF is derived from a precursor molecule and that the precursor is transformed into immunologically active NGF within the secretory granules during their transport from the basal to the apical part of the tubular cells. Stimulation of the submandibular gland with carbachol (2 mg/kg) led to a massive release of the content of the secretory granules, including NGF, into the salivary duct.
TL;DR: The significance of the morphological changes undergone by the gill epithelial cells after exposure to different salinities and heavy metal ion concentration, are discussed in relation to the physiological functioning of the gills.
Abstract: The effects of different salinities and concentrations of copper, mercury and cadmium ions on the gills of Jaera nordmanni are investigated by means of light and electron microscopy. After exposure to 10% and 50% sea water the gill epithelium cells show a marked uniformity in appearance, possessing characteristically large, sub-cuticular spaces which are prominent between microvilli. With exposure to the heavy metal ions a similar sequence of histological and ultrastructural changes occur in all the gill epithelial cells, culminating in cell breakdown. The ultrastructural changes include distended microvilli, dilated endoplasmic reticulum, dissociated ribosomes, diffuse (swollen) cytoplasm, swollen mitochondria and a basal membrane withdrawn from the basal lamina. An increase in the number of haemocytes is also commonly observed in the haemolymph spaces during heavy metal ion exposure. The significance of the morphological changes undergone by the gill epithelial cells after exposure to different salinities and heavy metal ion concentration, are discussed in relation to the physiological functioning of the gill.
TL;DR: The fine structure of the synapses and some features of their topological arrangement were studied within the SCN of the rat and all types of synapses (mostly GTII-synapses) can be enclosed by multilamellar astroglial formations.
Abstract: Within the suprachiasmatic nucleus (SCN) of the rat the fine structure of the synapses and some features of their topological arrangement were studied. Five types of synapses could be distinguished with certainty: Shape of clear vesicles: often oval; sucrose treatment partly produces flattening. Dense core-vesicles (dcv) are found in all GTII- and most of the GTI-synapses after three-dimensional reconstruction. All types of synapses (mostly GTII-synapses) can be enclosed by multilamellar astroglial formations. The synapses often occur in complex synaptic arrangements. Dendrites and somata of females show significantly more multivesiculated bodies than those of males. Further pecularities of presynaptic (PreEls) and postsynaptic elements (PostEls) within the SCN are described and discussed.
TL;DR: It is concluded that the subsarcolemmal mitochondria supply the energy for the active transport of metabolites through the sarcolemma in oxidative muscle fibers, and that they are the limiting factor for endurance performance of the soleus muscle fibers because the changes in the capillarization were only small.
Abstract: Rats, 6 weeks old, were subjected to a program of endurance running for 3, 6 and 12 weeks 05 to 08 μm thick sections of Epon embedded soleus muscles were studied with morphometric methods In cross-sections the area occupied by subsarcolemmal mitochondria was independent of the age, but was 53% higher after 12 weeks of training The mean depth of the zones with subsarcolemmal mitochondria increased only 15% to about 09 μm Thus, the subsarcolemmal mitochondria showed a pronounced spreading at the muscle fiber surface in trained muscles — The number of capillaries per fiber decreased slightly in controls and increased not significantly in trained muscles It is concluded that the subsarcolemmal mitochondria supply the energy for the active transport of metabolites through the sarcolemma in oxidative muscle fibers, and that they are the limiting factor for endurance performance of the soleus muscle fibers because the changes in the capillarization were only small It is suggested that the subsarcolemmal and the interfibrillar mitochondria have different functions and may therefore represent different types of mitochondria which can be distinguished by their morphology as well as by their biochemical properties
TL;DR: The main ultrastructural feature of dBcAMP-treated astroblasts is the presence of an extensive system of 90 Å microfilaments, while control cells are relatively devoid of these structures.
Abstract: Modifications of cell shape induced in cultured newborn rat astroblasts by serum deprivation or dibutyryladenosine 3′–5′ monophosphate (dBcAMP) are described. Serum suppression modifies the adhesivity of the cells to the substrate, but this modification is not consistent with a true differentiation. The main ultrastructural feature of dBcAMP-treated astroblasts is the presence of an extensive system of 90 A microfilaments, while control cells are relatively devoid of these structures.
TL;DR: Four of the small interneurons could be seen in whole-mount preparations and are demonstrated to be identical in five species of acridid grasshoppers of two different subfamilies: Schistocerca vaga, S. gregaria, Gastrimargus africanus, Trimerotropis pallidipennis, and Arphia conspersa.
Abstract: The anatomy of the small ocellar interneurons in the brain of the acridid grasshopper Schistocerca vaga was revealed by cobalt-filling the three ocellar nerves and subsequent reconstructions from silver-intensified (Timm's method) serial sections. In total, 61 small ocellar interneurons were repeatedly identified with arborizations in many areas of the brain and optic lobe, including in particular the posterior neuropil, ocellar tracts, protocerebral bridge, lobula, ventral bridge and tritocerebral crotch, calyces, and antenno-glomerular tracts. Each ocellar nerve contains the axons of small cells that arborize in the other two ocellar tracts; these tracts are sites of ocellar integration. Direct interactions between the ocelli and compound eyes are suggested by the projections of small ocellar interneurons into the proximal lobula. Small cell arborizations from all three ocelli are distributed actoss much of the protocerebral bridge, implying a role for the bridge as an ocellar neuropil within the brain. Four of the small interneurons could be seen in whole-mount preparations and are demonstrated to be identical in five species of acridid grasshoppers of two different subfamilies: Schistocera vaga, S. gregaria, Gastrimargus africanus, Trimerotropis pallidipennis, and Arphia conspersa.
TL;DR: A population of nerve fibres in the gastro-intestinal tract of mice showing a high affinity for quinacrine was revealed by fluorescence microscopy, and recent suggestions that “purinergic”, substance P, enkephalin, and somatosin-containing nerves, in addition to adrenergic and cholinergic nerves, are present in the gut wall are discussed.
Abstract: A population of nerve fibres in the gastro-intestinal tract of mice showing a high affinity for quinacrine was revealed by fluorescence microscopy. Similar results were obtained in rats and guinea pigs. Whole-mounts of sheets of the smooth muscle layer following incubation in 10(-6)-10(-7) M quinacrine for 15-60 min revealed fine fluorescent varicose nerve fibers in the myenteric plexus of Auerbach both around nerve cell bodies and in the interconnecting strands. Many fibers were also present between the strands of the plexus, especially running parallel to the circular muscle layer. Such fibers were not seen in similarly quinacrine-incubated irides. A proportion of the cell bodies in Auerbach's plexus also showed quinacrine accumulation. These cells were apparently smaller neurons, sometimes with fluorescent processes. Intraperitoneal injections of quinacrine failed to demonstrate nerve fibers, but some cell bodies in Auerbach's plexus were positive. Subsequent paraformaldehyde treatment for monoamine visualization showed persistent adrenergic nerve terminals in the intestine and iris. These nerves seemed to be fewer and had a more yellow fluorescence than normally. The identity of the quinacrine-positive fibers is discussed with respect to recent suggestions that "purinergic", substance P, enkephalin, and somatosin-containing nerves, in addition to adrenergic and cholinergic nerves, are present in the gut wall.
TL;DR: The gap junctions between the Leydig cells are frequently observed in both normal and feminized testes, and they are round or elliptic in contour and about several micrometers in diameter.
Abstract: Normal and feminized human testes were examined by means of freeze-fracture. In both cases, the junctional complexes between adjacent Sertoli cells show a unique characteristic feature. Many parallel linear occluding junctions are located circumferentially around the cell surface at the level of the nucleus. They are more than forty in number over one Sertoli cell surface. In the A face, the particles are not prominent on the ridge of the junctions. Instead, they are clearly seen in the center of the groove of the junctions on the B face. Gap junctions consisting of particle aggregation are not found between the Sertoli cells. The gap junctions between the Leydig cells are frequently observed in both normal and feminized testes. They are round or elliptic in contour and about several micrometers in diameter. The particles, about 8 nm in diameter, are closely packed to form a quasi-hexagonal pattern. The pits are found on the B face corresponding to the particle aggregation.
TL;DR: A light and electron microscopic study was performed on the baroreceptor axon terminals in the carotid sinus of guinea pigs and mice, using serial semithin and thin sections as mentioned in this paper.
Abstract: A light and electron microscopic study was undertaken on the baroreceptor axon terminals in the carotid sinus of guinea pigs and mice, using serial semithin and thin sections. Together with their enveloping Schwann cells, numerous lanceolate axon terminals are organized into a well-defined discoid end organ, referred to as the ‘baroreceptor unit’. Baroreceptor units measure 100 to 150 μm in diameter and are arranged in a hexagonal pattern. These end organs represent free branched lanceolate mechanoreceptors of complex type (Andres and von During, 1973) which belong to the main group of stretch receptors. In the guinea pig the lanceolate terminals enter the media and approach the innermost layers near the intima. In the mouse the terminals are seen to spread in the adventitia and along the medio-adventitial border. Only a few of them penetrate the external elastic layer. Species differences concerning the localization and extent of these visceral mechanoreceptors are discussed, as well as the modified architecture of the sinus wall in the receptor area (‘elastic segment’). Lanceolate terminals form beaded varicosities which are equipped with finger-like or lamellar axoplasmic protrusions. These projections contain a well-differentiated receptor matrix. They are attached to collagen and elastic fibers. The varicosities include densely packed mitochondria, neurotubules, profiles of axoplasmic reticulum, clear and granular vesicles, and striking accumulations of glycogen particles, lamellated bodies and lysosomes. Four types of varicosities are discerned according to their main axoplasmic components. Various types of these varicosities occur within an individual lanceolate terminal. The adrenergic innervation of the carotid sinus was studied by fluorescence histochemistry. In guinea pigs a multilayered wide-meshed plexus of fluorescent fibers occurs in the adventitia where it is closely related to baroreceptor stem fibers. However, adrenergic axons do not enter the media. In mice fluorescent fibers are extremely rare in the adventitia of the carotid sinus.
TL;DR: In Oryzias latipes the processes of spermatogenesis and spermiogenesis occur within testicular or germinal cysts which are delimited by a single layer of lobule boundary cells, which are deemed to be the homologue of mammalian Sertoli cells.
Abstract: In Oryzias latipes the processes of spermatogenesis and spermiogenesis occur within testicular or germinal cysts which are delimited by a single layer of lobule boundary cells. These cells, in addition to comprising the structural component of the cyst wall, ingest residual bodies cast off by developing spermatids. Therefore, they are deemed to be the homologue of mammalian Sertoli cells. The germ cells within a cyst develop synchronously owing to the presence of intercellular bridges connecting adjacent cells. Since bridges also connect spermatogonia, it seems probable that all of the germ cells within a cyst may form a single syncytium and do not exist as individual cells until the completion of spermiogenesis when the residual bodies are cast off. Significant differences between spermiogenesis in O. latipes and in the related poeciliid teleosts are discussed.
TL;DR: Immuno-enzyme cytochemical investigations, using single and double staining techniques, showed that the external region of the rat median eminence contains separate neurophysin-vasopressin fibres and neurophysine containing nerve fibres that are influenced by bilateral adrenalectomy and by colchicine treatment.
Abstract: Immuno-enzyme cytochemical investigations, using single and double staining techniques, showed that the external region of the rat median eminence contains separate neurophysin-vasopressin fibres and neurophysin-oxytocin fibres These neurophysin-hormone containing nerve fibres are influenced by bilateral adrenalectomy and by colchicine treatment The external region of the median eminence of the homozygous Brattleboro rat contains neurophysin-oxytocin fibres It does not contain immuno-reactive neurophysin-vasopressin fibres Bilateral adrenalectomy also influences the neurophysin-vasopressin containing neurons of the suprachiasmatic nuclei In the neurons of the parvicellular part of the rat hypothalamic paraventricular nuclei, staining for vasopressin and for oxytocin is completely absent
TL;DR: The synaptic complex between a retinula cell axon and four postsynaptic elements, arranged in a constant elongated array, and the “gnarl” complex in which a presynaptic specialization in one neuron is separated from another neuron by a complicated glial invagination are concentrated on.
Abstract: In the lamina ganglionaris, the first optic ganglion of the fly, the inventory of cell types as well as the patterns of their connections are well known from light microscopic investigations Even the synaptic contacts are known with relative completeness However, the structural details visible on electron micrographs are very difficult to interpret in functional terms This paper concentrates on two aspects: 1) the synaptic complex between a retinula cell axon and four postsynaptic elements, arranged in a constant elongated array (it is suggested that all synapses in which the retinula cell is presynaptic are of this kind), and 2) the “gnarl” complex in which a presynaptic specialization in one neuron is separated from another neuron by a complicated glial invagination The participation of glia at postsynaptic sites seems to be quite common in this ganglion Occasionally it seems that a glia cell is the only postsynaptic partner facing a presynaptic specialization within a neuron
TL;DR: Intracellular sporozoan parasites invade the host cell through the invagination of the plasma membrane of the host and a vacuole is formed which accommodates the entering parasite, which is left with a single membrane throughout its life span.
Abstract: Intracellular sporozoan parasites invade the host cell through the invagination of the plasma membrane of the host and a vacuole is formed which accommodates the entering parasite. The vacuole may disappear and the invaginated membrane of the host then becomes closely apposed to that of the parasite's own membrane. As a result the parasite is covered by two membranes. Members of the class Piroplasmea differ from other Sporozoa in that their trophozoites are covered by a single membrane. By screening numerous sections of intraerythrocytic Babesia microti belonging to the class Piroplasmea, it was found that merozoites of Babesia enter the erythrocytes of hamsters in the same way as those of the other Sporozoa. When a merozoite touches the red blood cell with its anterior end it becomes attached to the membrane of the host, which starts to invaginate and a parasitophorous vacuole is formed. The vacuolar space disappears rapidly and the membrane of the vacuole and that of the parasite become closely adjacent. At this stage the parasite is surrounded by two plasma membranes. The outer membrane derived from the invaginated host membrane disintegrates quickly and the parasite is left with a single membrane throughout its life span.
TL;DR: It was found that the proliferation of the normal mesenchymal cells adjacent to the activated and degranulated mast cells in the mesentery was significantly increased within 24 and 32 h, the maximum increase being more than 20-fold compared to untreated controls.
Abstract: The effect of mast cell activation and degranulation on the proliferation in the intact mesentery was studied in Sprague-Dawley rats. Mast cell activation was achieved by a single intraperitoneal injection of Compound 48/80. The proliferation was studied using three independent methods for estimation of cell production and DNA synthesis: 1. the mitotic index, 2. the relative number of cells having a DNA content in the S and G2 regions, by Feulgen photometric measurement in individual cells, and 3. the specific DNA activity, employing a method which combines a liquid scintillation technique after an intravenous injection of 3H-thymidine and Feulgen photometric determination of the DNA content per membrane preparation. It was found that the proliferation of the normal mesenchymal cells adjacent to the activated and degranulated mast cells in the mesentery was significantly increased within 24 and 32 h, the maximum increase being more than 20-fold compared to untreated controls. The results suggest that the common type of mast cell may have a pathophysiological function related to stimulation of local cell proliferation.
TL;DR: PTE-cultured osteoblasts showed an increase in cell overlap and contact so that a more competent barrier was formed separating the bone from the medium in control or CT medium, however, intercellular gaps were greater than in vivo.
Abstract: Neonate rat endocranial osteoblasts were cultured on their bone surfaces in control medium (CC) or medium to which either parathyroid extract (PTE) or calcitonin (CT) had been added for 2, 4, 8 or 24 h. Some were cultured for 24 h in CC, then for 2, 4, 8 or 24 h in either CT or PTE medium; or for 24 h in PTE, then for 2, 4, 8 or 24 h in either CC or CT; or 24 h in CT and 2, 4, 8 or 24 h in CC. The dorsal ruffling of the cells in CC was found to be suppressed by later culturing with PTE and the disoriented cells reorganized to form arrays of parallel cells. The effects of PTE were also reversed by CC or CT: the osteoblasts in the second culture (CC) lost elongation and order, and proceeded through a proliferative phase before exhibiting the ruffling form similar to a single CC 24 h culture. PTE-cultured osteoblasts showed an increase in cell overlap and contact so that a more competent barrier was formed separating the bone from the medium. In control or CT medium, however, intercellular gaps were greater than in vivo.