Showing papers on "Apical cytoplasm published in 1993"
TL;DR: Since iron in enterocytes remains in equilibrium with body stores, it is postulate mucosal iron uptake is regulated by the number of iron binding sites either occupied or unoccupied by iron on mobilferrin, and it accepts dietary iron from integrin and acts as the shuttle protein for iron in the cytoplasm.
Abstract: Newly identified iron binding proteins isolated from rat duodenal homogenates permit better understanding of iron absorption. Mucins bind iron at acid pH to keep iron soluble and available for absorption at the more alkaline pH of the duodenum; this explains iron deficiency following prolonged achlorhydria. Integrin (90/150 kD) was identified on the absorptive surface of enterocytes in association with radioiron and is believed to facilitate transit of iron through the microvillous membrane. Mobilferrin, a 56 kD iron binding protein, was isolated from enterocyte cytosol. It coprecipitates with integrin and appears in close association with integrins in the apical cytoplasm. We postulate it accepts dietary iron from integrin and acts as the shuttle protein for iron in the cytoplasm. Since iron in enterocytes remains in equilibrium with body stores, we postulate mucosal iron uptake is regulated by the number of iron binding sites either occupied or unoccupied by iron on mobilferrin. Iron repletion of enterocytes from body stores is accomplished via transferrin receptors on the posterolateral membranes of enterocytes. Increased transfer of iron from blood into absorptive enterocytes occurs in iron replete animals to inhibit mucosal uptake of dietary iron. Little transfer of iron from plasma to enterocytes occurs in iron deficiency. Enhanced mucosal transfer of iron into the body occurs with increased body need for iron. The exact mechanism for mucosal transfer of iron into the plasma has not been defined but may also be mediated by an integrin.
137 citations
TL;DR: There may be selectivity mediated by glycoconjugates in the uptake of antigenic material by cecal M cells but not by jejunal M cells, as suggested by the results.
83 citations
TL;DR: The development and maintenance of polarization in epithelial cells require the targeting and transport of specific proteins to the apical and basolateral plasma membrane, and it is proposed that a dynein-like, microtubule-based motor is involved in the transport of apically directed materials from the trans-Golgi to theApical plasma membrane.
Abstract: The polarization of intestinal epithelial cells and the stereotypic arrangement of their actin-based cytoskeleton have made these epithelia an excellent system to explore the organization and formation of a cortical actin-based cytoskeleton. Through a combined morphological and biochemical analysis, the molecular arrangement of many of the components of the brush border has been elucidated. Study of brush border assembly in the Crypts of Lieberkuhn suggests that cytoskeletal mRNA and protein expression, as well as morphological development, occur rapidly following cell differentiation. Protein kinases appear to be important regulators of intestinal cell growth, for differentiating cells in the crypts possess 15-fold higher levels of tyrosine phosphorylated proteins than differentiated cells of the villus. One of these kinases, pp60c-src, has a 4- to 7-fold higher activity in crypts and increased association with the cytoskeleton than it has in villus cells. The development and maintenance of polarization in epithelial cells require the targeting and transport of specific proteins to the apical and basolateral plasma membrane. It has been proposed that a dynein-like, microtubule-based motor is involved in the transport of apically directed materials from the trans-Golgi to the apical plasma membrane. However, microtubules do not reach the plasma membrane, but terminate below the actin-rich network of filaments comprising the terminal web. We propose that vesicles translocate from the Golgi to the apical cytoplasm along microtubules using dynein, and then move through the terminal web to reach the apical plasma membrane using the actin-based motor myosin-I.(ABSTRACT TRUNCATED AT 250 WORDS)
76 citations
TL;DR: Findings suggest that in the guinea pig, effete enterocytes are not simply exfoliated into the lumen, but are damaged by intraepithelial lymphocytes possessing a natural killer cytotoxicity, and subsequently phagocytosed by subepitocyte macrophages.
Abstract: Numerous macrophages were found aggregated in the lamina propria at the tips of villi in the small intestine of guinea pigs. These macrophages extended their pseudopodia into the epithelial lining and internalized fragments of effete enterocytes in their phagosomes. The epithelium of the villus tips was found to be infiltrated with numerous lymphocytes. They possessed electron-dense granules characteristic of natural killer cells, and actively interdigitated with the enterocytes. The latter were either fragmented or extensively lost in their basal cytoplasm, often leaving an attenuated apical cytoplasm of the cell. Immunohistochemical labeling using bromodeoxyuridine demonstrated that at 96 h after its administration, immunolabeled nuclei were encountered in the cytoplasm of macrophages in the lamina propria at the villus tips. These findings suggest that in the guinea pig, effete enterocytes are not simply exfoliated into the lumen, but are damaged by intraepithelial lymphocytes possessing a natural killer cytotoxicity, and subsequently phagocytosed by subepithelial macrophages.
49 citations
TL;DR: Mucins bind Fe at acid pH to keep it soluble and available for absorption at the more alkaline pH of the duodenum; this explains the development of Fe deficiency in achlorhydric subjects.
Abstract: Newly identified iron (Fe)-binding proteins isolated from both rat and human duodenal mucosa permit a better understanding of Fe absorption. Mucins bind Fe at acid pH to keep it soluble and available for absorption at the more alkaline pH of the duodenum; this explains the development of Fe deficiency in achlorhydric subjects. Integrin was identified on the surface of enterocytes in association with radioiron and is believed to facilitate the transfer of Fe through the microvillous membrane. Mobilferrin, a 56 kDa Fe-binding protein, was identified in enterocyte cytosol. It coprecipitates with integrin and appears in close association with integrin in the apical cytoplasm of absorptive cells. We postulate it accepts dietary Fe from integrin and acts as the shuttle protein from Fe in the cytoplasm. Since Fe in enterocytes remains in equilibrium with body stores, we postulate mucosal Fe uptake is regulated by the number of Fe-binding sites either occupied or unoccupied by Fe on mobilferrin. Fe repletion of e...
45 citations
TL;DR: The differences in immunostain pattern along the epididymis length seem to be related to regional differences in function.
Abstract: Our objective was to characterize epithelial cells, lamina propria, and sites of estrogen coupling in the caput, corpus, and cauda regions of the human epididymis using antibodies to cytokeratin types; epithelial membrane antigen; laminin; type IV collagen; vimentin; desmin-, and estradiol-receptor-related protein; and immuno-histochemical techniques. Principal cells immunostain by both AE1/AE3 antibodies (keratins 1-8, 10, 13-15, and 19) and anti-pan-keratin antibodies (keratin 5, 6, and 8). Immunoreactions to both anti-keratin antibodies increase from the caput to the cauda epididymis. The principal cells only immunostained by anti-keratin 19 antibodies in the cauda and showed no reaction to keratins 10 and 11. Basal cells and apical cells immunoreact to anti-AE1/AE3, antipankeratin, and antikeratin 19 antibodies, but not to antikeratin 10 and 11 antibodies, in all three epididymal regions. The principal cells immunoreact with epithelial membrane antigen antibodies in the stereocilia and subjacent cytoplasm. This immunostaining decreased from the caput to the cauda. Antivimentin antibodies stained the apical cytoplasm of principal cells and limited areas of both principal cells and basal cells. This immunoreaction decreased from the caput to cauda. Apical cells immunostained in the three regions. Immunoreaction to ER-D5 was moderate in the principal cells, basal cells, apical cells, and muscular coat cells in the cauda. The apical cells immunostained in the three regions. Antilaminin antibodies stained the epithelial basement membrane in the three regions. Type IV collagen was detected in the basement membrane as well as around the muscular coat cells in the three regions. Immunoreaction to desmin was intense in the muscular coat cells in the three regions.(ABSTRACT TRUNCATED AT 250 WORDS)
39 citations
TL;DR: The direct constitutive pathway is not involved in microvillous atrophy, and any transport defect in the disease probably involves a different, unidentified exocytotic pathway.
Abstract: Microvillous atrophy is a disorder within the intractable diarrhea of infancy syndrome. The disease is believed to stem from a transport defect that prevents exocytosis of brush border-related material. We investigated this hypothesis by examining the direct constitutive exocytotic pathway using sucrase-isomaltase as a representative protein. We also studied various other brush border and lysosomal marker enzymes. The biosynthesis and localization of selected intestinal epithelial enzymes were studied in small-intestinal mucosal biopsy specimens from a total of nine children with microvillous atrophy by: (a) metabolic labeling in organ culture, (b) radioiodination and immunoprecipitation, (c) indirect immunoperoxidase immunocytochemistry, and (d) immunogold electron microscopy. The results demonstrated that brush border enzymes were synthesized normally and could be located in the apical brush border membrane and on microvillous membrane within microvillous inclusions. Brush border enzymes were not detected in the "secretory granules" that accumulated within the apical cytoplasm of epithelial cells. Lysosomal enzymes were only detected within lysosomal bodies. Thus, the direct constitutive pathway is not involved in microvillous atrophy, and a disturbance of endocytosis or the indirect constitutive pathway is unlikely. Any transport defect in the disease probably involves a different, unidentified exocytotic pathway.
35 citations
TL;DR: The present findings support the accepted view that epithelial cells undergoing apoptosis are exfoliated as total, nucleus-containing cells in the guinea pig, and in the rat and mouse.
Abstract: Our previous study demonstrated that in the small intestine of guinea pigs, apoptotic epithelial cells at the villus tips were phagocytosed by lamina propria macrophages, leaving only apical cytoplasmic plates, which thereafter were domed and extruded into the lumen. This finding contrasts with the generally accepted view that effete epithelial cells are simply exfoliated into the lumen. In order to explain this discrepancy, the present study examined luminal cell elements of the small intestine in the guinea pig, rat and mouse; the latter two have been favored species for studying the kinetics of intestinal cells. Light and electron microscopic observations indicated that the luminal fluid of the guinea pig contained numerous cytoplasmic fragments covered with long microvilli and not containing a nucleus; these fragments corresponded with the apical cytoplasm of apoptotic epithelial cells. In the rat and mouse, in contrast, luminal cell elements were represented by round cell bodies possessing a nucleus and microvillous border; the nucleus displayed compaction and segregation of chromatin at the periphery, a microscopic figure characteristic of apoptosis. As far as the rat and mouse are concerned, the present findings support the accepted view that epithelial cells undergoing apoptosis are exfoliated as total, nucleus-containing cells. In the guinea pig, in contrast, only an apical thin plate of effete cells is shed off, as our previous studies have suggested.
34 citations
TL;DR: The findings suggest that non-ubiquitinated PGP immunoreactive proteins are secreted in the epididymis, mainly in the proximal caput, and attach to spermatozoa.
Abstract: A quantitative immunohistochemical study was performed of the distribution of protein gene product 9.5 (PGP, a soluble protein localized in neurons and neuroendocrine cells as well as in some non-nervous cells) and ubiquitin along the rat epididymis. In the ductuli efferentes, PGP immunoreaction was observed in the whole cytoplasm of some columnar cells; a smaller number of columnar cells showed ubiquitin immunoreactivity with limited apical and basal cytoplasmic localization. In the proximal caput epididymidis, the whole cytoplasm of all columnar cells showed PGP immunoreactivity, ubiquitin immunostaining was negative in this region. In the middle and distal caput epididymidis and the distal cauda, the apical cytoplasm of some columnar cells and the whole cytoplasm of some basal cells showed immunoreactivity to PGP. In these regions, immunoreactivity to ubiquitin was positive in the supranuclear cytoplasm of some columnar cells but not in the basal cells. No immunoreactivity to PGP or ubiquitin was detected in the corpus epididymis and the proximal cauda. Double immunostaining revealed that all the epididymal ubiquitin immunoreactive cells were also PGP immunoreactive, whereas most PGP immunoreactive cells did not immunoreact to ubiquitin. In ubiquitin-PGP immunoreactive cells, the site of the PGP immunoreaction differed from that of the ubiquitin immunoreaction. PGP-ubiquitin immunoreactive cells also seemed to be immunoreactive to anti-AE1/AE3 keratin antibodies. The spermatozoal heads were immunoreactive to PGP antibodies in the epididymal regions from proximal caput to distal cauda but not in the ductuli efferentes. The findings suggest that non-ubiquitinated PGP immunoreactive proteins are secreted in the epididymis, mainly in the proximal caput, and attach to spermatozoa.
30 citations
Journal Article•
TL;DR: Results demonstrating a three-dimensional model for the vacuolar apparatus involved in the endocytosis and membrane recycling pathway of the proximal tubule cells suggest that DAT originate mainly from SEV but also from LEV, illustrating that membrane recycling occurs at any stage of the initial endocytic process, and implies that most membrane material return to the cell surface via a short, fast recycling route.
Abstract: The present study was performed to examine the three-dimensional structure of the vacuolar apparatus involved in endocytosis and especially the membrane recycling pathway of rat renal proximal tubule cells by electron microscopy of serial sections. In five series of consecutive ultrathin sections, endocytic invaginations (INV), small endocytic vacuoles (SEV; 0.5 micron in diameter) and dense apical tubules (DAT) were followed. LEV connected to SEV and dense apical tubules were reconstructed from these sections, and the distribution, size, shape and spatial relationships were examined. The analysis of small coated profiles (< 0.5 micron in diameter) in the apical cytoplasm showed that the INV account for 21.3%, SEV connected to DAT account for 36.4% while SEV free in the cytoplasm account for 42.3%. The free SEV generally have a larger diameter than those connected to DAT. Of the DAT, 56.5% are free in the cytoplasm, 36.9% are seen connected to SEV and 6.5% are in continuity with LEV. The reconstructed images showed that LEV are spherical structures connected to DAT and SEV. A quantitative analysis showed that the smaller the surface area of LEV, the higher the relative number of DAT connected, and also shown was that the number of DAT attached to SEV is 2.03 times more than that of DAT connected to LEV. These results demonstrating a three-dimensional model for the vacuolar apparatus involved in the endocytosis and membrane recycling pathway of the proximal tubule cells suggest that DAT originate mainly from SEV but also from LEV, illustrating that membrane recycling occurs at any stage of the initial endocytic process, and implies that most membrane material return to the cell surface via a short, fast recycling route.
26 citations
TL;DR: The present study shows that the IGF-II/Man-6-P receptor is located in components of the vacuolar system in the apical cytoplasm of rat renal proximal convoluted tubule cells, mainly in S1.
TL;DR: The ultrastructure of renal tubule cells was studied in the European lesser spotted dogfish by the evaluation of thin sections and freeze fracture replicas and bound sites of a polyclonal antibody against an extraplasmic portion of rat gastric H+‐K+‐adenosine triphosphatase (ATPase) were observed at the apical cell membrane.
Abstract: The ultrastructure of renal tubule cells was studied in the European lesser spotted dogfish by the evaluation of thin sections and freeze fracture replicas. Computer-assisted three-dimensional reconstruction of entire nephrons was performed. The distinction of nephron segments and collecting tubule was made using results of previous histological work. The first proximal tubule segment (PI) consists of two subsequent portions, PIa and PIb. PIa is a component of the lateral countercurrent bundle, and PIb, which displays an apical tubulovesicular apparatus and an extended lysosomal compartment, is located in the vicinity of the glomeruli. Rod-shaped intramembrane particles were detected in PIa. The second proximal tubule segment (PII) is a special segment in elasmobranch and teleost fish. PII differs largely from PI in cell morphology and function. The apical cytoplasm was filled with small clear vesicles, and an apical endocytic apparatus was lacking. In the apical cell membrane, rod-shaped particles were revealed by freeze fracture. The apical tight junctions of PI and PII consisted of seven to ten meandering strands. The distal nephron was subdivided into two major segments: early distal tubule (EDT) in the lateral countercurrent bundles and late distal tubule (LDT) in the mesial tissue. The EDT showed marked amplification of basolateral cell membranes. The tight junctions displayed a low number of continuous parallel strands, which is also characteristically found in the diluting segments of other vertebrates. LDT cells showed cytoplasmic studs and rod-shaped intramembraneous particles at the apical cell membrane, thereby resembling type A intercalated cells of collecting duct. The collecting tubule (CT) emerged from the LDT and was part of the countercurrent arrangement inside the lateral bundles. Tight junctions of LDT and CT consisted of many meandering strands in a honeycomb pattern. With immunohistochemistry, binding sites of a polyclonal antibody against an extraplasmic portion of rat gastric H(+)-K(+)-adenosine triphosphatase (ATPase) were observed at the apical cell membrane of PIa, PII, and LDT. From the colocalization of binding sites for the antibody against the transport enzyme with rod-shaped intramembrane particles, we assume that these might be the morphological correlate of gastric H(+)-K(+)-ATPase-like enzyme in the renal tubule.
TL;DR: Results indicate that the intracellular canaliculi are formed by expansion of the apical surface and suggest that the delivery of newly synthesized gastric H+/K+ ATPase α and β subunits to the apicals plasma membrane is mediated by typical Golgi transport vesicles.
Abstract: The early development of the parietal cell in the embryonic murine gastric mucosa was investigated with particular attention paid to the biogenesis of the secretory membranes and the localization of the gastric H+/K+ ATPase alpha and beta subunits. Gastric glands were recognized in the day 18 foetus. However, at this stage in development no parietal cells could be distinguished ultrastructurally in the glands, and no immunoreactivity was detected with monoclonal antibodies to either the alpha or beta subunits of the gastric H+/K+ ATPase. In the 19 day embryo, parietal cells were recognizable morphologically by the presence of slender microvilli on the apical (lumenal) surface and differentiating intracellular canaliculi in the apical cytoplasm. Both subunits of the proton pump were found to be specifically associated with the apical and canalicular membranes and with the membranes of relatively large vesicles distributed in the subapical cytoplasm and the cytoplasm surrounding the canaliculi. In the parietal cells of the day 1 neonate, the intracellular canaliculi had extended basally to form the extensive compartments typical of parietal cells in the adult animal. Again, profiles of vesicles showing H+/K+ ATPase immunoreactivity were present in the pericanalicular cytoplasm. These results indicate that the intracellular canaliculi are formed by expansion of the apical surface and suggest that the delivery of newly synthesized gastric H+/K+ ATPase alpha and beta subunits to the apical plasma membrane is mediated by typical Golgi transport vesicles. The large immunoreactive vesicles that occur in the apical and pericanalicular cytoplasm of the developing cells may represent artefacts generated by fixation-induced fragmentation of the differentiating canalicular membrane system during preparation.
TL;DR: Observations showed that there are at least three compartments involved in the accretion of IgG in the small intestine of neonatal piglets: smaller apical endocytotic vesicles, large subnuclear granules and crystalloid inclusions.
Abstract: Enterocytes of the small intestine in 1-day-old suckling piglets contain numerous vesicles in the apical cytoplasm and a large granule located beneath the nucleus. Within the next 3 days, these granules transform into electron-dense crystalloid inclusions. These membrane-bound inclusions are up to 10 μm in length and 1–2 μm in diameter, and they are composed of electron-dense lamellae 3.9 nm apart. Postembedding immunocytochemistry, using rabbit anti-porcine IgG and goat anti-rabbit IgG conjugated to 10 nm colloidal gold, revealed that both the granules and the crystalloid inclusions contained a high concentration of maternal IgG. Although the IgG content of the crystalloid inclusions was detected on epoxy-embedded sections, the use of LR White resin resulted in a much higher density of labelling. Quantification of the labelling density showed that the concentration of IgG in the crystalloid inclusions was approximately ten times higher than that in the lumenal colostrum and approximately three times higher than that in the granules. These observations showed that there are at least three compartments involved in the accretion of IgG in the small intestine of neonatal piglets: smaller apical endocytotic vesicles, large subnuclear granules and crystalloid inclusions. The role of these compartments in maternal immunoglobulin absorption and in the acquisition of passive immunity has yet to be explored.
TL;DR: Results indicate that the disruption of MF, rather than MT, contributes to the transformation of the uterine luminal cell surface during the lead up to blastocyst attachment.
TL;DR: The head, body, and tail regions of the epididymal duct in two healthy and sexually mature Sus domesticus males were examined by light microscopy and by scanning or transmission electron microscopy.
Abstract: The head, body, and tail regions of the epididymal duct (or caput, corpus, and cauda epididymis) in two healthy and sexually mature Sus domesticus males were examined by light microscopy and by scanning or transmission electron microscopy. The epididymal duct is lined with a pseudostratified epithelium with stereocilia and covered by a muscular-connective tissue sheath that is thickest in the tail region. Diameter of the epididymal duct and height of epididymal epithelium are maximal in the head region. Length of the sterocilia and spermatic density are higher in the head and body regions. Somatic cells are abundant in the tail region. The epididymal epithelium is made up of five cell types: basal cells, principal cells, clear cells, narrow cells, and basophilic cells. Abundant secretory units are observed in the supranuclear cytoplasm of columnar principal cells. Each mature secretory unit is constituted by electron-dense secretion granules covered by more than eight layers of cisternae of reticulum between which the mitochondria are intercalated. In the apical cytoplasm the isolated secretion granules become larger and less electron dense. The apical surface is covered by numerous sterocilia. Basal cells are pyramidal and less high than principal cells. The clear cells, arranged between the principal cells, are characterized by the presence of abundant vesicular elements and electron-lucid secretion granules, and by an apocrine secretory process. The narrow cells are characterized by their highly vacuolized cytoplasm. Intermediate cell typologies can be found among basal, principal, clear, and narrow cells, which could be four developmental stages of the same cell type. The basophilic cells are spheroidal and are found at different levels between the epithelial cells and in the connective tissue underlying the epithelium. © 1993 Wiley-Liss, Inc.
TL;DR: These studies show that a polarized tubulovesicular transcytotic pathway exists in rat biliary epithelium and is microtubule dependent.
TL;DR: The fine structure of the otolithic organs in fetal and neonatal rats were studied by light and transmission electron microscopy and the functional roles of protrusions and cytoplasmic globules in the genesis of otoconia remain to be clarified.
Abstract: The fine structure of the otolithic organs in fetal and neonatal rats were studied by light and transmission electron microscopy. The otoconia were found at the 16.5 gestational day while the otolithic membrane appeared much later. Types II and I hair cells were first observed at the 16.5 and 18.5 gestational days, respectively. Secretory granules in the supporting cells seemed to release an organic material which was destined to be incorporated into the organic matrix of the otoconia and/or the otolithic membrane. Protrusions of apical cytoplasm, cytoplasmic globules and dilated rough endoplasmic reticulum (rER) were observed in epithelial cells of both sensory and non-sensory regions, in particular, in the transitional cells. By contrast, otoconia were mainly located above the neuroepithelial area. The functional roles of protrusions and cytoplasmic globules in the genesis of otoconia remain to be clarified. In addition, the pathway for transport of calcium remains obscure.
TL;DR: The fine structure of urothelial cysts in 11 patients diagnosed cystoscopically as suffering from cystitis cystica was studied, finding that the deeper cells contained relatively fewer organelles, while a basal lamina separated the cyst wall from the underlying connective tissue.
Abstract: Cystitis cystica, a common urothelial pathology whose aetiology, morphology and clinical significance are poorly understood, affects the human urinary bladder and trigone in both sexes. We have studied the fine structure of urothelial cysts in 11 patients diagnosed cystoscopically as suffering from cystitis cystica. Several abnormal features were observed in the adjacent urothelium, including large intracellular vacuoles (4 patients), Brunn's nest (5), lymphocyte infiltration (10) and generally disorganised urothelial architecture (10). Squamous metaplasia was observed in one case. The wall of each cyst consisted of a 2-3 layered epithelium with either tall columnar or flattened cells lining the fluid-filled lumen. Both types of lining cell possessed short microvilli, while the columnar type also contained numerous membrane-bound, electron dense secretory granules in the apical cytoplasm. Rough endoplasmic reticulum, mitochondria and Golgi membranes were plentiful in the surface cells. Junctional complexes joined adjacent lining cells. The deeper cells contained relatively fewer organelles, while a basal lamina separated the cyst wall from the underlying connective tissue.
TL;DR: The distribution of microtubules and microfilaments in larval and adult salivary glands of Drosophila melanogaster were examined by conventional fluorescence microscopy and laser scanning confocal microscopy, showing some regional differentiation.
Abstract: We examined the distribution of microtubules and microfilaments by conventional fluorescence microscopy and laser scanning confocal microscopy in larval and adult salivary glands of Drosophila melanogaster. The cells of the larval salivary gland epithelium were characterized by the same spatial distribution of microfilaments, whereas microfilament localization was more complex in adult salivary glands, showing some regional differentiation. Microtubules distributed throughout the cell cytoplasm of the larval salivary glands, whereas in adult glands they were mostly observed in the basal or apical cytoplasm of the cells. These observations were related to the secretory process and the mechanism of saliva discharge.
TL;DR: The most unique feature of the blood supply was the existence of large sinusoidal vessels extremely variable in shape.
Abstract: Harderian glands from male and female Octodon degus were examined by light and transmission electron microscopy. Two types of secretory units, designated as type I and type II, were observed. Type I secretory units comprise three types of epithelial cells: Cells packed with numerous lipid droplets (Type a), cells with few Hpid droplets (Type b), and cells with numerous mitochondriae and a very well developed Golgi complex (Type c). Type II secretory units were found exclusively in female Octodon degus and comprised a type of secretory cells which contained numerous basophilic granules in their apical cytoplasm. In addition, in female Octodon degus , clusters of lymphocyte-like cells and plasmatic cells were also observed. The vascularization of the gland appeared very well developed. The most unique feature of the blood supply was the existence of large sinusoidal vessels extremely variable in shape. In the medullar region, the sinusoidal wall adapts its contour to that of the tubuloalveolar surface. Unmyelinated and myelinated nerve fibers were found in the connective stroma of the gland.
TL;DR: The distribution of MIM-1/39 was different from that reported for IgA, bound and free secretory components, cryptdin, and Tamm-Horsfall protein, and appears to be a unique protein.
Abstract: We have previously shown that monoclonal antibodies (MAb) prepared against the duodenal mucosa of 4-day-old mice disclosed the presence of two antigens associated with the formation of intestinal crypts. One of these, MIM-1/39, was found in the apical cytoplasm of undifferentiated epithelial crypt cells of the duodenum and colon. We report here the immunolocalization of MIM-1/39 in different glands associated with the gastrointestinal tract, using a polyclonal antibody produced against antigen MIM-1/39. By indirect immunofluorescence on 1-micron thick Lowicryl K4M sections, MIM-1/39 was detected in secretory granules of serous cells in lingual (von Ebner's gland), sublingual, submandibular and parotid glands, and in pancreas; it was also found in epithelial cells of the gallbladder and in the secretory granules of chief cells of gastric glands. Liver, kidney, and Brunner's glands were not immunoreactive. Immunocytochemistry revealed the presence of antigen MIM-1/39 in small secretory granules of the gallb...
TL;DR: The accumulation of suramin in the apical region of the cells is consistent with previous data showing that suramin elicited a lysosomal storage disorder in HT29-D4 cells by a mechanism of polarized endocytosis.
TL;DR: The differences between the enzymohistochemical and immunohist biochemical patterns of the efferent ducts and those of the epididymis may help to explain functional differences along the epidIDymis.
Abstract: Summary
An enzymohistochemical and immunohistochemical study of the efferent ducts was performed in normal adult men. The epithelium donsists of two types of columnar cells: principal cells (PCs) and ciliated cells (CCs), and is surrounded by a lamina propria (LP) with cells arranged circularly (LPCs). Enzymohistochemical study revealed more intense activity of succinic dehydrogenase, NADP, and ATPase in the CCs than in the PCs. The LPCs also showed an intense reaction for NADP and ATPase. Acid phosphatase activity was only intense in the apical cytoplasm of PCs. Immunohistochemical study revealed that antibodies to oestradiol receptor-related protein (ER-D5) immunostained the PCs and CCs intensely and the LPCs weakly. AEl/AE3 antibodies (which stain keratins nos. 1–8 and14, 15 and 19) immunostained the PCs intensely, but was negative in both CCs and LPCs. Antibodies to keratin Ks.4.62 (which stain keratin no. 19) immunostained PCs and CCs but not LPCs. Epithelial membrane antigen antibodies (EMA) immunostained the adluminal surface and apical cytoplasm of PCs. Anti-vimentin antibodies immunostained the cytoplasm of PCs and CCs weakly as well as isolated cells in the LP. Antibodies to desmin immunostained most LPCs. Antibodies to collagen IV immunostained the basal lamina and many extracellular spaces in the LP, mainly around the LPCs. The differences between the enzymohistochemical and immunohistochemical patterns of the efferent ducts and those of the epididymis may help to explain functional differences along the epididymis.
TL;DR: In this paper, a complex system of cytokeratin filaments and microtubules radiate through the whole cytoplasm of ciliated cells with direct contact to the nucleus, cilia, microvilli, desmosomes and to the apical terminal adhesive complex.
Abstract: Observations of explanted bronchial mucosa show that ciliary function is maintained for 7 days subsequent to explantation. This finding demonstrates that non-neural mechanisms exist which regulate ciliary function. Ultrastructural and immunohistochemical studies both for light and electron microscopy were performed on human bronchial biopsy material and lung resection specimens in order to recognize the morphological substrate of this regulatory mechanism. A complex system of cytokeratin filaments and microtubules radiate through the whole cytoplasm of ciliated cells with direct contact to the nucleus, cilia, microvilli, desmosomes and to the apical terminal adhesive complex. Between the basal bodies and the apical terminal adhesive complex microfilaments can be found. In the apical cytoplasm a dense filamentary network is seen in association with the adhesive complex. These morphological findings indicate that the cytoskeleton of the bronchial epithelium plays a key role in the co-ordination of ciliary function.
TL;DR: For the first time the development of the alimentary tract of Levinseniella brachysoma metacercaria (Trematoda: Microphallidae) obtained experimentally from Gammarus oceanicus has been described and on the basis of an analysis of the ultrastructural data the possible functioning of the meetacercarial aliments tract is discussed.
Abstract: For the first time the development of the alimentary tract of Levinseniella brachysoma metacercaria (Trematoda: Microphallidae) obtained experimentally from Gammarus oceanicus has been described. The foregut primordium in 16-day-old metacercariae is represented by a syncytial cylindrical cord, resulting from the fusion of embryonic cells. Non-fused parts of the plasma membranes of adjacent cells are revealed as gap cavities within the cord. Later (30th day post infection) the lumen of the foregut is formed as a result of both partial vacuolization of the cytoplasm and by a broadening of the gap cavities, resulting from a thinning of the cytoplasmic spaces between them. Besides the usual organelles, the foregut of the mature metacercaria (42nd day p.i.) contains dense secretory granules in the apical cytoplasm region and numerous microtubules in basal areas. The cellular gastrodermis is formed later than the foregut syncytium (on day 30 p.i.); its large cells contain well-developed Golgi complexes, RER and mitochondria. A noteable inclusion of the gastrodermal cells of mature metacercariae are spherical granules of moderate electron density measuring up to 3 μm in diameter. On the basis of an analysis of the ultrastructural data the possible functioning of the metacercarial alimentary tract is discussed.
TL;DR: Most of the ultrastructural changes observed here seemed to be related to a heightened metabolic activity, namely active or increased protein synthesis, in response to the parasitism.
Abstract: Summary The ultrastructural changes in the bursal epithelial cells of chickens infected with Cryptosporidium sp. were investigated. The principal features were as follows: deep invaginations or indentations of the nucleus with separate lobulations in some instances, nucleolar hypertrophy with formation of reticular or open nucleolonema, increase or swelling of mitochondria, increase in coated vesicles, ribosomes and well‐developed rough endoplasmic reticulum (RER), increase in mitochondrial‐RER association, appearance of small, smooth‐membraned vacuoles in the apical cytoplasm, and formation of electron dense fibres. In addition, nuclear bodies, thin‐shelled or ring‐shaped nucleoli, nucleolar segregation, nucleolar margination, ribo‐some‐lamella complex, microtubuloreticular complex, disaggregation of polysomes and vesiculation of RER were rarely observed. Most of the ultrastructural changes observed here seemed to be related to a heightened metabolic activity, namely active or increased protein synthesis...
TL;DR: The present study indicates that the cell of the Brunner's glands become active in secretory granule formation just after birth by responding to ingested material following birth.
Abstract: Perinatal changes of the Brunner’s glands in rats from fetal day 20 through neonatal day 3 were studied morphometrically and electron-microscopically. Percentage volume of secretory granules of the gland cells did not change from fetal day 20 through neonatal day 1 and increased significantly from neonatal days 1-2; this level was maintained through neonatal day 3. Electron-microscopically, the gland cells during the fetal days were rich in free ribosomes. The Golgi apparatus and rough-surfaced endoplasmic reticulum (RER) were poorly developed during fetal days. After birth, however, the cells showed active formation of secretory granules, which was evidenced by well-developed Golgi apparatus, distended RER and accumulation of granules in the apical cytoplasm. Furthermore, light microscopy revealed that strongly PAS-positive material increased for the first time after birth, indicating remarkable formation of the secretory granules. Thus, the present study indicates that the cell of the Brunner’s glands become active in secretory granule formation just after birth by responding to ingested material following birth.
TL;DR: The ependymal cells of the subcommissural organ in the domestic chicken synthesize a complex oligosaccharide for a secretory product which is discharged into the ventricular cavity and in the basal cytoplasm and basal processes, only oligosACcharides containing large amount of mannose are present.
Abstract: The properties and distribution of the secretory substance in the ependymal cells of the subcommissural organ in the domestic chicken were examined with seven different lectins, using the avidin-biotin-peroxidase complex method. On the ventricular surface of this organ, LFA, PNA, RCA-I and WGA reacted positively. In the apical cytoplasm, Con A, LFA, RCA-I and WGA gave positive reactions. On the other hand, only Con A and WGA gave positive reactions in the basal cytoplasm. In the hypendymal vascular wall, LFA, RCA-I and WGA reacted positively. Neuraminidase digestion completely inhibited reactions with LFA and reduced the WGA reaction within the apical cytoplasm. At the same time, this digestion disclosed a moderately positive reaction with PNA in the apical cytoplasm. The significant findings of this study may be summarized as follows: 1) the ependymal cells of the subcommissural organ in the domestic chicken synthesize a complex oligosaccharide for a secretory product which is discharged into the ventricular cavity; 2) in the basal cytoplasm and basal processes, only oligosaccharides containing large amount of mannose are present.
TL;DR: The presence of large whorls of rough endoplasmic reticulum and abundant free ribosomes in the cytoplasm and nuclei with multiple, well-developed nucleoli indicate that the epithelial cells are actively engaged in protein synthesis.
Abstract: The rectal pads of the primitive insect Grylloblatta compodeiformis (Orthoptera : Grylloblattidae) were studied using light and electron microscopy. In this species, the rectal epithelium is thickened to form 6 prominent rectal pads, each of which is composed of tall columnar epithelial cells and laterally placed slender junctional cells, but is devoid of secondary cells. The rectal pads are interconnected by simple rectal epithelium, and are lined by a thin cuticular intima. They are surrounded by an extensive connective tissue space, which contains bundles of delicate connective tissue fibers, neurosecretory axons, and tracheae and tracheoles, which do not penetrate into the pads. The epithelial cells exhibit extensive infoldings of the apical plasma membranes that are closely associated with mitochondria. The lateral membranes are also highly folded around large mitochondria that possess longitudinally oriented cristae. These membrane folds form mitochondrial-scalariform junctional complexes and enclose intercellular channels and spaces. The apical cytoplasm of the epithelial cells contains numerous coated vesicles, dense tubular elements, multivesicular bodies and lysosomes, which suggests receptor-mediated endocytosis of macromolecules. The presence of large whorls of rough endoplasmic reticulum and abundant free ribosomes in the cytoplasm and nuclei with multiple, well-developed nucleoli indicate that the epithelial cells are actively engaged in protein synthesis. The ultrastructural features were examined in relation to their role in fluid transport in a cold habitat.