Showing papers on "Apical cytoplasm published in 1994"

Cathepsin B expression in colorectal carcinomas correlates with tumor progression and shortened patient survival.

Abstract: Cathepsin B is a lysosomal cysteine proteinase that has the ability to degrade several extracellular matrix components at both neutral and acidic pH and has been implicated in the progression of several human and rodent tumors. We have studied the expression of cathepsin B in human colorectal tissues using a monospecific polyclonal rabbit antibody raised against human liver cathepsin B. In immunoblots of normal and neoplastic colorectal tissues this antibody specifically recognized only cathepsin B. We studied 101 cases of formalin-fixed, paraffin-embedded tissue (15 normal mucosa, 17 adenomas, and 69 carcinomas). Epithelial cells of normal mucosa and adenomas were either negative or showed a weak granular reactivity located in the paranuclear and apical cytoplasm of superficial cells. Small clusters of histiocytes were also positive in the region of the superficial area of the lamina propria. In carcinomas, increased expression of cathepsin B correlated with advanced stage of the disease. Increased immunoreactivity of cathepsin B in malignant cells was associated with either a diffuse cytoplasmic staining or was polarized to the basal pole of the cells. This is in contrast to the punctate paranuclear staining pattern observed in normal colonic mucosal cells. In tumor stromal cells, increased expression of the enzyme correlated with neoplastic progression. Expression of high levels of cathepsin B in the tumor epithelial cells was associated with a significantly shorter survival of the patients. In conclusion, our results indicate that cathepsin B expression is up-regulated in human colorectal carcinomas compared with normal mucosa and adenomas and correlates with tumor progression.

Molecular motors are differentially distributed on Golgi membranes from polarized epithelial cells

Abstract: Microtubules (MT) are required for the efficient transport of membranes from the trans-Golgi and for transcytosis of vesicles from the basolateral membrane to the apical cytoplasm in polarized epithelia. MTs in these cells are primarily oriented with their plus ends basally near the Golgi and their minus-ends in the apical cytoplasm. Here we report that isolated Golgi and Golgi-enriched membranes from intestinal epithelial cells possess the actin based motor myosin-I, the MT minus-end-directed motor cytoplasmic dynein and its in vitro motility activator dynactin (p150/Glued). The Golgi can be separated into stacks, possessing features of the Golgi cisternae, and small membranes enriched in the trans-Golgi network marker TGN 38/41. Whereas myosin-I is present on all membranes in the Golgi fraction, dynein is present only on the small membrane fraction. Dynein, like myosin-I, is associated with membranes as a cytoplasmic peripheral membrane protein. Dynein and myosin-I coassociate with membranes that bind to MTs and cross-link actin filaments and MTs in a nucleotide-dependent manner. We propose that cytoplasmic dynein moves Golgi membranes along MTs to the cell cortex where myosin-I provides local delivery through the actin-rich cytoskeleton to the apical membrane.

Gs alpha stimulates transcytosis and apical secretion in MDCK cells through cAMP and protein kinase A.

Abstract: Recent evidence suggests a role for heterotrimeric G proteins in vesicular transport. Cholera toxin, which activates Gs alpha by ADP-ribosylation, has been reported to stimulate both apical secretion (Pimplikar, S.W., and K. Simons. 1993. Nature (Lond.). 352:456-458) and apically directed transcytosis (Bomsel, M., and K.E. Mostov. 1993. J. Biol. Chem. 268:25824-25835) in MDCK cells, via a cAMP-independent mechanism. Here, we demonstrate that apical secretion and apically directed transcytosis are significantly stimulated by agents that elevate cellular cAMP. Forskolin, which activates adenylyl cyclase directly, and 8BrcAMP augment both transport processes in MDCK cells. The increase is not limited to receptor-mediated transport (polymeric Ig receptor), since transcytosis of ricin, a galactose-binding lectin, is similarly stimulated. The effects of elevated cellular cAMP on apical secretion and transcytosis are apparently mediated via protein kinase A (PKA), as they are inhibited by H-89, a selective PKA inhibitor. Experiments employing a 17 degrees C temperature block indicate that cAMP/PKA acts at a late, possibly rate-limiting stage in the transcytotic pathway, after translocation of internalized markers into the apical cytoplasm. However, no significant stimulus of apical recycling was observed in the presence of FSK, suggesting that cAMP/PKA either affects transcytosis at a level proximal to apical early endosomes and/or specifically increases the efficiency by which transcytosing molecules are delivered to the apical plasma membrane. Finally, we overexpressed wild-type Gs alpha and a mutant, Q227L, which constitutively activates adenylyl cyclase, in MDCK cells. Although Q227L increased transcytosis more than wild-type Gs alpha, neither construct was as effective as FSK in stimulating transcytosis, arguing against a significant role of Gs alpha in transcytosis independent of cAMP and PKA.

Secretion of group 2 phospholipase A2 by lacrimal glands.

Abstract: PURPOSE Tears are known to have antimicrobial properties The authors investigated the presence of the antibacterial enzyme phospholipase A2 (PLA2) in tears and lacrimal glands METHODS The catalytic activity of PLA2 and the amount of pancreatic group 1 PLA2 and nonpancreatic group 2 PLA2 were measured in homogenates of eight human lacrimal glands from autopsied subjects and in tears from four healthy volunteers The localization of PLA2s in lacrimal gland sections was studied by immunohistochemistry Skeletal muscle was used as a control RESULTS The catalytic activity of PLA2 was significantly higher in lacrimal glands than in skeletal muscle Immunochemical analysis showed significantly higher amounts of group 2 PLA2 in lacrimal gland than in skeletal muscle homogenates Group 1 PLA2 was present in trace amounts only The concentration of group 2 PLA2 in tears was high (14513 micrograms/l) compared to that in the serum of healthy individuals (37 micrograms/l) By immunohistochemistry, a granular reaction of group 2 PLA2 was localized in the glandular cells of lacrimal glands The apical cytoplasm of many duct cells also was labeled CONCLUSIONS The lacrimal glands secreted nonpancreatic group 2 PLA2, which most likely acts as an antiinfectious factor in tears

Colocalization of cytokeratin 18 and villin in type III alveolar cells (brush cells) of the rat lung.

Abstract: Alveoli of the rat lung are lined by three different cell types, the flat type I cells and the cuboidal type II and type III cells. Type III cells differ from type II cells by the presence of an apical tuft of microvilli and the absence of lamellar type secretory granules. In the present study we show by double immunolabelling that type III cells of the rat lung can be identified at the light- and electron microscope level by antibodies against both cytokeratin 18 and the actin-crosslinking protein villin. At the ultrastructural level, microvilli and their rootlets in the apical cytoplasm were labelled by the anti-villin antibodies, whereas a monoclonal antibody against cytokeratin 18 (Ks18.04) labelled bundles of intermediate filaments. In conclusion, antibodies against villin and certain monoclonal antibodies specific for cytokeratin 18 can be used as tools for selective visualization of type III cells in the rat lung.

Evidence for cryptosporidial infection as a cause of prolapse of the phallus and cloaca in ostrich chicks (Struthio camelus)

Abstract: Cloacas of male ostrich chicks that had suffered prolapse of the phallus and cloaca were compared with cloacas of normal ostrich chicks of both sexes from the same area. Heavy infection of the cloacal and bursal tissue with Cryptosporidium sp. was present in all the cases of prolapse, while no cryptosporidia were observed in the normal chicks. Histopathological lesions as described in cryptosporidial infection in other species were present in the infected cloacas. These included loss of the microvillous border and epithelial hyperplasia and degeneration, which was indicated ultrastructurally by vacuolation of the apical cytoplasm, swelling of organelles, and nuclear changes. It is suggested that these lesions, in combination with the anatomy of the male ostrich cloaca, may be responsible for prolapse of the phallus and cloaca.

Specific in situ Hybridization of the Intracellular Organism of Porcine Proliferative Enteropathy

Abstract: The identity of the intracellular bacteria found in the enterocytes of pigs with proliferative enter- opathy was investigated using specific DNA probes to various Campylobacter species and to a novel organism, ileal symbiont intracellularis. The ilea from pigs (Nos. 1-7) that were diagnosed by routine histopathology as having proliferative enteropathy were used. Diagnosis was made on the basis of proliferation of the enterocytes on hematoxylin and eosin-stained sections and the presence of large numbers of intracellular curved organisms on Warthin-Starry silver-stained sections. Four of these pigs (Nos. 1-4) had the chronic form of the disease, porcine intestinal adenomatosis, and three (Nos. 5-7) had the acute form, proliferative hemorrhagic enteropathy. An additional three normal pigs (Nos. 8-10) were obtained from three separate farms with no history of proliferative enteropathy. Frozen ileal sections were examined by in situ hybridization with DNA probes specific for ileal symbiont intracellularis and the three porcine intestinal Campylobacter species, C. coli, C. hyointestinalis, and C. mucosalis. In all seven pigs with either the intestinal adenomatosis or hemorrhagic enteropathy form of the disease, a DNA probe specific for ileal symbiont intracellularis hybridized to localized foci in the apical cytoplasm of ileal enterocytes. These hybridization sites corresponded to the location of intracellular bacteria in silver-stained sections of adjacent tissue. Sections from the three normal pigs tested with this probe and from all pigs tested with the Campylobacter species-specific DNA probes showed no specific hybridization reactions. The identity of the intracellular organism in these diseased pigs is ileal symbiont intracellularis.

Regional variations in the ultrastructural features of secretory cells in the rat oviductal epithelium.

Abstract: Background: In mammals, the oviductal secretory cells and their secretions play important roles in reproductive and developmental events. Therefore, many electron microscopic studies of mammalian oviductal epithelial cells have been performed. Methods: The secretory cells in various regions of the rat oviduct during the estrous cycle were examined by transmission electron microscopy. Results: In the fimbriae, the secretory cells contained small secretory granules with moderately electron-dense matrices and many large bodies that resembled lipid droplets. In the ampullar cells, small secretory granules with moderately electron-dense matrices were observed in the apical cytoplasm. In the isthmus, the secretory cells contained numerous secretory granules with moderately electron-dense matrices. Electron-dense areas were frequently observed in many of the granules of the isthmic cells. Vesicles, partially filled with a dense substance, frequently were observed in the isthmic cells and occasionally in the ampullar cells. Very long stereocilia projected from the surfaces of the isthmic secretory cells into the lumen. Exocytosis of the secretory granules was observed. In addition, there was evidence to suggest the release of the bodies that resembled lipid droplet occurred. Cysts and ciliated vacuoles that appeared to be intraepithelial were frequently observed in the fimbrial and ampullar epithelia. No dramatic changes in the relative numbers of ciliated and secretory cells in any oviductal segment were observed during the estrous cycle. Conclusions: Our ultrastructural observations of the rat oviduct revealed marked regional variations in the morphological features of secretory cells. These results may provide insight into regional and cellular differences in the function of the rat oviduct. © 1994 Wiley-Liss, Inc.

H3-thymidine labeled cerebrospinal fluid contacting cells in the regenerating caudal spinal cord of the lizard Lampropholis.

Abstract: Summary Australian scincid lizards ( Lampropholis ) were injected with a single dose of H3-thymidine during the early stages of tail regeneration in order to study later a possible differentiation of neurons and glial cells within the regenerating spinal cord. After 5 hours post-injection only elec-trondense or pale ependymal cells took up H3-thymidine. Light and electron microscopic analysis of later stages, 6, 12 and 20 days post-injection, revealed that labeled pale cells were occasionally recognizable 12–20 days post-injection. Many pale unlabeled and a few labeled cells contacted the central canal of the spinal cord and appeared as cerebrospinal fluid contacting cells. The electron microscope showed the presence of stereocilia in the apical cytoplasm of these pale cells, a typical characteristic of cerebrospinal fluid contacting neurons. After 12–20 days post-injection, among ependymal cells rare pale cells containing intermediate filaments were labeled. Other pale cells represented intermediate stages of differentiation between ependymal and neural or glial cells. Differentiated medium-high electrondense ependymal tanicytes were also labeled 6, 12 and 20 days post-injection. This analysis showed that a limited regeneration of cerebrospinal fluid contacting neurons occurs locally in the caudal spinal cord of the scincid lizard Lampropholis .

Electron Probe X-ray Microanalysis of Epithelial Cells: Aspects of Cryofixation

Abstract: Content and distribution of diffusible ions in epithelial cells were studied by scanning transmission electron microscopy and energy dispersive electron probe X-ray microanalysis of freeze-dried cryosections from trout kidney, rat liver and Malpighian tubules of Drosophila larvae. Cryofixation of small excised kidney and liver samples by rapid immersion into liquid propane resulted in intracellular K/Na-ratios 7 were obtained after in situ cryofixation by means of a cryopunching device which allows tissue pieces to be frozen during excision from the intact organ. Isolated hepatocytes cryofixed in a small droplet of culture medium had a K/Na-ratio of 3.7. After culturing the hepatocytes, the K/Na-ratio increased to 24. Effects of extracellular media of different composition on the intracellular element content were studied. Malpighian tubules of Drosophila larvae were cryofixed by rapid immersion into liquid propane, and the distribution of K across the cells forming the tubules from the basal to the apical cell membrane was measured. An increasing K gradient was found from the intermediate to the apical cytoplasm. The intracellular K distribution was dependent on ions and transport inhibitors present in the fluid surrounding the Malpighian tubules within the larvae. Content and distribution of ions in epithelial cells sensitively depend on the physiological state immediately before cryofixation. Thus, electron probe X-ray microanalysis of cells and cell functions requires careful selection and control of the cell system to be studied.

Antibodies to the 280-kd coated pit protein, target of teratogenic antibodies, produce alterations in the traffic of internalized proteins.

Abstract: Previous studies have identified two high-molecular weight (280 and 330 kd) glycoproteins expressed by coated pits of the proximal renal tubule and yolk sac and have further established that, in vivo, antibodies to gp280 but not to gp330 induce fetal malformations. In the present study, we report the effect of these antibodies on the endocytic process by yolk sac visceral epithelial cells of rat embryos explanted at day 10 of gestation. Antibodies to gp280 markedly altered development of the yolk sac and embryo, induced malformations, inhibited by 40% the uptake of [14C] sucrose and perturbed the intracellular traffic of internalized proteins. Under control conditions, rat immunoglobulin G present in the culture medium was immunolocalized in lysosomes of epithelial cells, whereas in the presence of antibody, it was detected in small vesicles scattered through the apical cytoplasm. Alterations of the endocytic pathway were confirmed by experiments analyzing the uptake of peroxidase added to the medium for 2 to 60 minutes. The initial compartments of endocytosis visualized by peroxidase were increased in size and abnormal in shape and the transfer of the internalized peroxidase to the lysosomal compartment was delayed. In contrast, antibodies to gp330 had a minimal effect on embryonic development and did not induce fetal malformations. Endocytosis was only modestly altered; uptake of [14C] sucrose was decreased by 25%, and only minor modifications of the intracellular transit of peroxidase could be detected. We suggest that the key role of anti-gp280 antibodies is via trapping of the target antigen in the early endocytic compartment thus preventing its normal function in lysosomal transfer.

Erythrocyte Indices and Volume Distribution in a Dog with Stomatocytosis

Abstract: tected in any other organs, including uterus, ureter, and regional lymph nodes. Histologically, the mass was surrounded by fibromuscular stroma and consisted of irregular tubular structures of various sizes focally invading the muscular layer; the major vestibular gland and ducts were present at the periphery of the mass (Fig. 2). There was marked infiltration of histiocyte$, lymphocytes, and plasma cells and formation of reactive lymphoid follicles throughout the mass. The tubules were lined by single or double layers of eosinophilic anaplastic cuboidal or columnar cells with apical microvilli. The proliferated lining cells had large oval nuclei and prominent nucleoli and numerous mitotic figures (Fig. 3) and periodic acid-Schiffpositive mucin in the apical cytoplasm. Some glandular structures were dilatated and cystic or irregularly shaped, occasionally filled with degenerated cells, necrotic debris, and infiltrated histiocytes. Based on its large size and the histopathologic findings, the neoplasm was diagnosed as a primary carcinoma in the major vestibular gland (which has not been previously reported in domestic animals), although there was no metastasis nor apparent histologic transition between the neoplastic mass and the normal tissue observed in contact with the mass. Human carcinomas of the major vestibular gland have been described as adenocarcinomas and squamous, adenoid cystic, transitional, adenosquamous, and undifferentiated carcinomas and usually metastasize to regional lymph nodes. The present bovine case showed no metastasis. Adenocarcinomas usually produce mucin,* but this bovine mass seemed to be much less active in production of mucin, which is actively produced in the normal bovine major vestibular gland.3 Carcinomas of the major vestibular gland occur predominantly on the left side, as in the present case, but the reason for this predilection is unknown.’

Differentiation of clara cells and pneumocytes of the rat by means of enzyme‐ and immunohistochemistry

Abstract: Localization of non-specific esterases, Cu-Zn superoxide dismutase and dehydropeptidase-I, in rat lung was investigated enzymecytochemically or immunohistochemically. Esterase was demonstrated in Clara cells, type II pneumocytes, and septal cells (or vitamin A-storing lung cells), to a somewhat lesser extent in type I pneumocytes and ciliated epithelial cells of the bronchioles, and to a minor extent in interstitial fibroblasts of the alveolar septum. Large amounts of esterase reaction product were deposited in the rough endoplasmic reticulum and the nuclear envelope in Clara cells, type II pneumocytes, and septal cells, in addition to smaller amounts in other organelles. No reaction product was found in macrophages (histiocytes) in alveolar septi and alveolar macrophages, except for the primary lysosomes or phagolysosomes and trace amounts in the Golgi vesicles, and none in endothelial cells of alveolar blood capillaries, except for primary lysosomes. Immunolocalization of Cu-Zn superoxide dismutase was generally limited to a particular area of Clara cells. A constriction occurred in the apical cytoplasm of Clara cells between an immunoreactive dome-like protrusion and the non-immunoreactive cytoplasm of the supranuclear area, and the dome-like protrusion appereared to be pinched off in a ball-like or oval from. Immunolocalization of dehydropeptidase-I was demonstrated in a dome-like protrusion or supranuclear area of Clara cells or throughout the cytoplasm and in the surface plasma membrane of mesothelial cells. The presence of these enzymes in Clara cells suggests a contribution to the detoxification system of the lung, together with cytochrome p-450-dependent monooxygenase systems. © 1994 Wiley-Liss, Inc.

Ultrastructure of the Male Accessory Glands and Sperm Ducts of Cylindrotaenia hickmani(Cestoda, Cyclophyllidea)

Abstract: The ultrastructure of unicellular accessory glands (=prostate glands) and external male ducts of the cestode Cylindrotaenia hickmani are described. Accessory glands open into the lumen of the external common sperm duct (=external vas deferens). The gland cells contain abundant endoplasmic reticulum, Golgi bodies and secretory bodies, and have elongate necks that pierce the apical cytoplasm of the duct. Cell contact with the apical cytoplasm of the sperm duct is mediated by septate desmosomes. Accessory glands secrete spherical particles, with a diameter of approximately 70 nm, that adhere to spermatozoa. The roles of these accessory glands may relate to activity of the sperm or development of the female system after insemination. Paired sperm ducts arise from testes, and unite to form a common sperm duct. Each duct consists of a tubular anucleate cytoplasmic region which is supported by nucleated cytons that lie sunken in the parenchyma. The apical cytoplasm of the paired sperm ducts (=vasa efferentia) possesses apical microvilli and abundant mitochondria, but few other cytoplasmic features. The apical cytoplasm of the common sperm duct possesses sparse apical microvilli and numerous electron-lucent vesicles. The male gonoducts form an elongate syncytium which is markedly polarized along the length of the ducts. The ducts also display apical-basal polarity in that sunken nucleated cytons support the apical cytoplasm which in turn has distinct basal and apical domains.

Transient expression of [D-Ala2] deltorphin I-like immunoreactivity in prenatal rat small intestine.

Abstract: We studied the distribution of immunoreactive elements for [D-Ala2] deltorphin I (DADTI), a delta-opioid receptor ligand, in fetal and postnatal rat small intestine. DADTI-like immunoreactive cells were detected transiently on embryonic Days 20 and 21. Electron microscopic examination revealed that positive staining occurred in mucous epithelial cells, either mature goblet cells or undifferentiated cells containing only a few mucous granules. Positive immunoreaction products in mature goblet cells were confined in their apical cytoplasm to the luminal parts of mucous granule aggregates. The result suggests that a DADTI-like molecule(s) is synthesized in rat intestinal goblet cells and is secreted in a diacrine fashion into the intestinal lumen at a late fetal period. The molecule(s) thus secreted may be important for the intestine of rats just before birth, because DADTI-like immunopositive goblet cells are no longer seen at any postnatal period.

Ultrastructure of the digestive system of the cercaria of Sanguinicola inermis Plehn, 1905 (Digenea: Sanguinicolidae)

Abstract: The digenean blood fluke Sanguinicola inermis and the family Sanguinicolidae have previously been described as apharyngeate and sucker-less. Examination of the digestive tract of the cercaria of S. inermis with transmission electron microscopy (TEM), however, has confirmed the presence of a well-developed and complex muscular region immediately adjacent to the sub-terminal mouth. The presence of this muscular region, which may be an oral sucker, emphasises the need for further ultrastructural studies on other members of the family. The adjacent oesophagus, composed of modified tegument, has distinct anterior and posterior regions. TEM shows that the surface of the posterior oesophagus is deeply folded and the apical cytoplasm and sunken cytons become filled with secretory granules, eventually forming a “secretory region” adjacent to the intestine. The dorsal, sac-like intestine is composed of a single layer of epithelial cells, the apical surface of which is drawn into shallow folds. Each cell contains numerous secretory granules, rough ER, and a single basal nucleus. The intestinal lumen, which contains electrondense striated bodies, is filled with fibrous material. Only two sensory oral papillae are associated with the digestive tract, positioned either side of the mouth opening and possibly acting as tango-, stretch- or pressure receptors. The papillae comprise several microtubules lying beneath the apical cytoplasm of the tegument within a nerve process, but there is no connection with the external body surface. The morphology of the alimentary canal of the S. inermis cercaria is discussed in relation to the functioning of the digestive system in preparation for establishment in the final host.

Localization of brush border cytoskeletal proteins in gastric oxynticopeptic cells from the bullfrog Rana catesbeiana.

Abstract: The contribution of brush border cytoskeletal proteins (actin, villin, fimbrin, and brush border myosin-1) to organization of the cytoskeletal network underlying apical plications of oxynticopeptic cells was examined by immunohistochemical techniques in frozen sections of gastric mucosa from the bullfrog, Rana catesbeiana. Apical localization of F-actin with phalloidin in oxynticopeptic cells inhibited with cimetidine revealed small, punctate domains within the apical cytoplasm that were consistent with the presence of short microvilli revealed by electron microscopy. Localization of F-actin in cells stimulated with forskolin was limited to a wide continuous band of cytoplasm corresponding to the location of numerous long surface folds. Inhibition of protein synthesis with cycloheximide did not prevent acid secretion or formation of actin filaments within surface folds in stimulated oxynticopeptic cells, suggesting that the formation of filaments does not require actin synthesis. Staining of gastric mucosae with fluorescent DNase-1 demonstrated that oxynticopeptic cells possess an unusually large pool of non-filamentous actin. Taken together, these results suggest that actin-filament formation in stimulated cells occurs by polymerization of an existing pool of non-filamentous actin. Localization of antibodies specific for villin and fimbrin revealed that these proteins were present within intestinal absorptive cells and gastric surface and neck cells but were not present within inhibited or stimulated oxynticopeptic cells. Brush border myosin-1, present in intestinal absorptive cells, was not present in gastric epithelium. Thus, we propose that actin-containing projections in oxynticopeptic cells are not organized like intestinal microvilli and that filament formation occurs after stimulation by modulating intracellular pools of filamentous and non-filamentous actin.

Localization of [D-Ala2]deltorphin I-like immunoreactivity in perinatal rat respiratory system.

Abstract: The localization of [D-Ala2]deltorphin I, a δ-opioid receptor ligand, was studied in the lower respiratory tract of developing rats using an immunohistochemical method. [D-Ala2]-like immunoreactive cells were detected first in the principal bronchus as early as embryonic day 16. As embryos grew, positive cells became gradually visible everywhere from principal bronchi to respiratory bronchioles. The density of positive cells reached the highest level on embryonic day 21, but decreased gradually after birth. Positive cells were no longer seen on postnatal day 30 in any region of the airways. No positive cells were ever found in the trachea or alveoli of rats at any age studied. Ultrastructural examination indicated that the immunoreactive cells possessed a similar morphology to serous or Clara cells of the respiratory epithelium. Immunoreaction products tended to locate at the apical cytoplasm of positive cells. The result suggests that [D-Ala2]-like molecule(s) may be expressed transiently in serous cells or Clara cells, or both, of the rat bronchopulmonary tract. Such a molecule may act as a pulmonary growth-promoting or a differentiation-initiating factor in an early period of lung development.

Three-dimensional architecture of the tubular endocytic apparatus and paramembranous networks of the endoplasmic reticulum in the rat visceral yolk-sac endoderm.

Abstract: The three-dimensional architecture of the tubular endocytic apparatus and the endoplasmic reticulum in the rat yolk-sac endoderm was investigated after loading with horseradish peroxidase-conjugated concanavalin A by intrauterine administration. After 30 min, small vesicles (50–150 nm in diameter), small tubules (80–100 nm in diameter) and large vacuoles (0.2–1.0 μm in diameter) in the apical cytoplasm were labeled with the tracer, but lysosomes (1.0–3.5 μm in diameter) in the supranuclear cytoplasm were not labeled until 60 min after loading. Stereo-viewing of the labeled small tubules in thick sections revealed that they were not isolated structures but formed three-dimensional anastomosing networks, which were also confirmed by scanning electron microscopy after maceration with diluted osmium tetroxide. Their earlier labeling with the endocytic tracer, localization in the apical cytoplasm and three-dimensional network formation indicated that the labeled small tubules represented tubular endosomes (tubular endocytic apparatus). These well-developed membranous networks provided by the tubular endosomes are suggested to facilitate the receptor-mediated endocytosis and transcytosis of the maternal immunoglobulin in the rat yolk-sac endoderm. Scanning electron microscopy further revealed lace-like networks of the smooth endoplasmic reticulum near the lateral plasma membrane. Their possible involvement in transport of small molecules or electrolytes is discussed.

Function of the cytoskeleton in cells with microridges from the oral epithelium of the carp Cyprinus carpio

Abstract: Superficial cells of the oral mucosal epithelium in the carp and the cytoskeleton of the epithelial cells are examined by scanning and transmission electron microscopy. Microridges are formed on the surface of the epithelium. Epithelial cells contain two types of vesicles: mucous secretory vesicles and coated vesicles. Most of the mucous vesicles are situated in the center of the cell near the Golgi apparatus. In freeze-fracture replicas, intramembranous particles are abundant in the membranes of the secretory vesicles but rare in the apical plasma membrane. Coated vesicles are situated in the apical and subapical cytoplasm. A great number of thick filaments, considered to be keratin filaments, run randomly throughout the cell to form a meshwork. Thick filaments, which are sparse in the central cytoplasm, are connected to the membranes of the secretory vesicles and other membranous organelles. A layer of closely packed thin filaments, considered to be actin filaments, is found just beneath the apical plasma membrane. Microtubules also occur in the apical cytoplasm and run almost parallel to the cell surface. Both kinds of vesicles are connected to the thin and thick filaments. Their functional significance in the regulation of membrane at the free surface is discussed.

Ecological Consequences of Altering the Timing Mechanism for Metamorphosis in Anural Ascidians

Abstract: Synopsis. In the present study the timing of metamorphosis in an anural ascidian, Molgula pacifica, was compared to metamorphosis in a urodele species Boltenia villosa. Metamorphosis in M. pacifica was triggered at a fixed time in development (32-36 hours after fertilization), just prior to hatching. In contrast, metamorphosis was triggered in B. villosa after the hatched larvae responded to substrate cues. The timing of metamorphosis in B. villosa was often delayed for up to four days, whereas delays in M. pacifica were not observed. An antibody, termed Epi-3, was found to cross-react exclusively with epidermal cells in both species. The binding of FITC-labelled Epi-3 was very low prior to metamorphosis and then it increased dramatically after metamorphosis was triggered. The cytoplasm of ampulla tip cells and the tunic immediately surrounding each ampulla showed the highest levels of Epi-3 fluorescence. The histological and ultrastructural features of the ampulla cells suggest that Epi-3 antibody recognizes granules localized in the apical cytoplasm. How the evolution of an internal "clock" mechanism responsible for initiating metamorphosis may be beneficial to anural species is discussed. One possibility is that the anural type of timing mechanism reduces mor? tality rates during this critical phase of its life cycle.

An X-ray microanalytical study on the effects of ouabain and N-ethyl maleimide on the elemental concentrations in Malpighian tubule cells of Locusta.

Abstract: X-ray microanalysis was used to study elemental distribution in Malpighian tubule cells of Locusta migratoria and how these are affected by the replacement of bathing medium K+ with Rb+ and by inclusion of the transport inhibitors ouabain and n-ethyl maleimide (NEM) in standard (K+-containing) and Rb+-Ringer (K+-free) solutions. Incubation of tubules in standard Ringer containing 1mM ouabain dramatically affected the intracellular levels of K and Na. The intracellular K concentration fell and Na concentration increased in all regions studied. Despite this, a gradient of increasing K concentration from basal to apical cell surface was maintained. Ouabain also reduced the intracellular levels of Rb when applied in Rb+-Ringer. Cl and P levels were unaffected by ouabain treatment. Incubation in standard and Rb+-Ringer solutions containing 1 microM NEM caused a significant increase in intracellular K levels in all regions of the cell compared with that observed in the absence of NEM. Rb levels were little affected by NEM except in the apical cytoplasm and microvillar regions where they were significantly reduced compared with Rb+-Ringer controls. NEM effected a significant increase in cellular levels of Na under Rb+-Ringer conditions. Intracellular Cl and P were not significantly affected by NEM. These results are discussed in relation to proposed mechanisms for the transport of ions and water across this secretory epithelium, with particular emphasis on the role of K+ as the 'prime mover' in this process.

Ultrastructure of the digestive system of adult Sanguinicola inermis.

Abstract: The alimentary tract of adult Sanguinicola inermis Plehn, 1905 (Digenea: Sanguinicolidae) was studied by transmission electron microscopy. A highly developed muscular region, likely to be a modified sucker, is present anteriorly to the oesophagus. The tegumental oesophagus, on the basis of the characteristics of the surface cytoplasm, is differentiated into anterior, median and posterior regions with the apical cytoplasm of the median oesophagus drawn into extracellular vesicles from which arise surface knobs. The oesophagus leads to a cellular intestine composed of a single layer of epithelial cells. The apical surface of the intestine is drawn into short luminal projections and the intestinal cells contain numerous organelles and secretory granules. No host cells or cell debris were evident within the alimentary tract, although the intestinal lumen was filled with electron-dense material.

The significance of prostate markers in the orthology of the female prostate

Abstract: In addition to knowledge gained in the first half of the 8th decade, the evidence of cross-antigenicity between male prostate and Skene's glands by means of PSA and PSAcP demonstrations in Skene's glands and ducts justifies utilization of the term prostate in both sexes. The authors compared the results of immunohistochemical examination of prostatic markers by means of the PAP method which was used at the beginning of the 8th decade, with that of BSAP technique. Prostatic tissues of 11 females and children at the age ranging from 5 to 71 years were examined. The results gained by means of the BSAP method were identical with those gained by means of the PAP method. Prostatic markers PSA and PSAcP were expressed on the surface and in apical cytoplasm of cells lining the prostatic ducts, and in prostatic glands. The authors proved the expression also in membranes of the stratified cylindrical epithelial cells of the ducts, and in female prostatic fluid in ducts and glands, especially PSAcP. Even though both immunohistochemical methods brought identical results, the authors recommend to prefer the BSAP method to the PAP method due to optically more contrast expression. (Fig. 8, Ref. 36.)

Localization of glycoconjugates in dog parotid gland by lectin histochemistry.

Abstract: Parotid glands from adult dogs were stained with a battery of seven horseradish peroxidase-conjugated lectins (PNA, UEA, LTA, DBA, SBA, WGA and ConA). In some cases (PNA and DBA) neuraminidase digestion was followed by lectin staining. Acinar cells contained conspicuous quantities of oligosaccharides with terminal sialic acid radicals. Galactosil-(β1→3)N-acetylgalactosamine was the most abundant penultimate sugar linked toN-acetylneuraminic acid. Sialylated components having the terminal dimer sialic acid-N-acetylgalactosamine were found in the acinar cells. Secretory cells presented a heterogeneous distribution of glycoconjugates with terminal fucose and β-N-acetylgalactosamine. Fucose,N-acetylglucosamine and α-N-acetylgalactosamine were present on the apical cytoplasm and surface of the striated and interlobular duct cells. This glycosidic composition was unaffected by extensive selective breeding. The role of abundant amounts of sialic acid radicals in the oral mucosa was considered.

Ultrastructure of the ootype of the lung fluke Paragonimus ohirai (Digenea, Troglotrematidae) in mated and single-infection worms.

Abstract: The ootype ofParagonimus ohirai was studied by both scanning and transmission electron microscopy. The ootype wall in 20-week-old worms from single infections was similar in its epithelial cell architecture and components to that of mated worms at 10 weeks postinfection. The lining epithelium consisted of a single layer of nucleated cells. The cytoplasm displayed a variety of organelles such as occasional Golgi complexes, well-developed annulate lamellae, frequent lysosomes, abundant mitochondria, and numerous ribosomes, suggesting high activities of intracellular synthesis and digestion. The former three organelles were generally located in the apical cytoplasm protruding into the lumen and may be significant in participating in regulation of egg formation. The present comparative studies suggest that the ootype epithelium can mature even by single infections and that the organized intracellular activities remain developed in single worms even after prolonged infection.

Bauhinia purpurea agglutinin (BPA) binding sites in human gastrointestinal tract.

Abstract: The binding of biotinylated BPA to parraffin sections of 18 normal gastrointestinal tract mucosa, 5 nonneoplastic polyps (NNP), 12 adenomas, and 59 carcinomas was studied by using avidinbiotin peroxidase complex (ABC) technique. In normal mucosa BPA appeared to bind both mucus and nonmucus glycoproteins but goblet cell mucus showed a decrease in binding and increase in binding of nonmucus glycoproteins as the cells lose their differentiation. BPA showed characteristic binding patterns in adenoma and carcinoma that differed from the pattern in normal mucosa. In normal mucosa linear binding to the apical cytoplasm in the columnar cells of the surface epithelium was observed, whereas in adenomas and carcinomas, in addition to the linear binding to the apical cytoplasm, diffuse cytoplasmic and granular deposits in the supranuclear, paranuclear or infranuclear zones were seen. Our findings suggest that BPA binding patterns in normal and neoplastic mucosa are related to the degree of cellular differentiation. In the process of malignant transformation the carbohydrate distribution undergoes progressive changes through the adenoma carcinoma sequence. These changes are related to the degree of dysplasia in adenomas and to the degree of differentiation in carcinomas.