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1.
It is well known that some caspases in apoptosis is involved in determinant of terminal differentiation and maturation of various cells. Our previous study ultrastructurally clarified the differentiation into M cells from immature microvillous epithelial cells and the redifferentiation from M cells to microvillous epithelial cells in the follicle-associated epithelium (FAE) of rat Peyer's patch. In this study, the difference of epithelial apoptosis between the FAE of Peyer's patch and intestinal villi was immunohistochemically investigated in rat jejunoileum. As a result, cleaved caspase-3 was limited to several epithelial cells at the tip of FAE, whereas almost all of the epithelial cells were cleaved caspase-3 positive in intestinal villi. Cleaved caspase-9 was detected only in a few exfoliating or exfoliated epithelial cells of both FAE and intestinal villi. Nuclear DNA-fragmentation was detected only in several epithelial cells of the tip of FAE, while it was expressed from the middle regions in the intestinal villi. The DNase I expression of the epithelial cytoplasm was much weaker in FAE than in intestinal villi. Bcl-x expression was restricted in the apical cytoplasms of epithelial cells in the FAE, whereas it was restricted in whole cytoplasms in villous epithelial cells. These findings suggest that the progression of the apoptotic process in the epithelial cells of FAE is later than in the intestinal villi, so that the possibility of epithelial differentiation might be remained in the FAE, unlike in the intestinal villi.  相似文献   

2.
The cellular kinetics of villous columnar epithelial cells and M cells in the rabbit small intestine were determined by the use of 5-bromo-2'-deoxyuridine (BrdU) as a tracer. To identify M cells, vimentin antibody was used. The BrdU-labeled nuclei of columnar epithelial cells reached the base of intestinal villi in all portions at 1 day after BrdU administration. Thereafter, BrdU-labeled cells migrated toward the villous tip, but they did not move at a uniform speed. The epithelial cells which existed in intestinal villi on circular folds moved faster than those on mucosa other than circular folds. At 7 days after BrdU administration, the leading edge of BrdU-labeled epithelial cells already disappeared from the villous tip in all portions of the small intestine. In the ileal Peyer's patch, the BrdU-labeled nuclei of microvillous epithelial cells and vimentin-positive M cells appeared near the intestinal crypt orifice at 1 day after BrdU administration, and then migrated toward the luminal surface of the follicle-associated epithelium (FAE). As they moved toward the upper portion of FAE, the number of BrdU-labeled M cells on the side of the dome decreased simultaneously. The leading edge of BrdU-labeled epithelial cells disappeared from the top of the FAE within 7 days. These results suggest that M cells may differentiate from the undifferentiated cells in intestinal crypts within 1 day and disappear from the top of the FAE after the change of their form from M cells into microvillous epithelial cells.  相似文献   

3.
The process of the disappearance of epithelial cells was examined in chicken cecal villi and follicle-associated epithelium (FAE). The apoptotic epithelial cells with intense DNA-fragmentation and their exfoliation were found in the villous tips. The epithelial cells with weak DNA-fragmentation were seen in the upper portion of the villi and their sparse exfoliations were also found there. Numerous epithelial cells in the intestinal lumen expressed the apoptotic features. A row of apoptotic epithelial cells with DNA-fragmentation was also found in the apical FAE, whereas no M cells exhibited any apoptotic signs. In all cecal regions, CD3+, CD8+, and TCR2+ lymphocytes were predominant in the epithelium at the upper portion of the villi and the FAE. CD4+ lymphocytes were mainly seen in the lamina propria. TCR1+ lymphocytes were not abundant in comparison with TCR2+ lymphocytes in the epithelium. TCR3+ T lymphocytes were rarely detected. These results suggest that the chicken cecal epithelial cells exfoliated into the lumen after the induction of the apoptosis, and that the induction may be involved with CD3+, CD8+, and TCR2+ lymphocytes. No death in M cells suggests that M cells may transform into microvillous epithelial cells.  相似文献   

4.
The differentiation process of immature microvillous epithelial cells to M cells and the fate of M cells in the follicle-associated epithelium (FAE) of the mucosa-associated lymphoid tissues are still unclear. In this study, the differentiation process and the fate of M cells were clarified in rat Peyer's patches under a transmission electron microscope. Almost all immature epithelial cells were found to possess long, slender microvilli, which gradually shortened, thickened and dispersed as the immature epithelial cells migrated away from the crypt orifices. These morphological changes started in the centers and moved to the peripheries of the apical surfaces of epithelial cells, accompanied by the protrusion of apical cytoplasm out of the terminal web. During these changes, the bundles of microfilaments of microvilli never shortened, and both small vesicles in the apical cytoplasm and tiny invaginations of the apical membranes were found. The intraepithelial migrating cells gradually accumulated to form typical intraepithelial pockets. In all FAE, there was no morphological sign of cell death in M cells. The rearrangement of microfilament bundles, the reconstruction of microvilli and the disappearance of pockets resulted in the transformation of M cells into microvillous epithelial cells. These serial ultrastructural changes suggest that M cells are a temporal and transitional cell type caused by the active engulfment of luminal substances and that when the engulfment ceases, the M cells transform into mature microvillous epithelial cells.  相似文献   

5.
Transmission and scanning electron microscopy of the ileal mucosae from 12 calves infected with Cryptosporidium sp. showed cryptosporidia free in the lumen and attached to epithelium. The attached parasites were interpreted to be extracellular and adherent to the microvillous border of epithelial cells. Stages of the organism included crescentic-free merozoites, trophozoites, schizonts, gametes and oocysts. Attached parasites were detected chiefly at villous tips and all stages were present on a single villus. Attachment sites were characterized by absence or disintegration of microvilli, disorganization of the terminal web and development of a specialized attachment zone. There were increased numbers of lysosomes and irregularities in the nuclear membrane of parasitized epithelial cells. It was concluded that cryptosporidia exist in bovine intestine as extracellular parasites and cause epithelial changes that in turn probably cause or contribute to diarrheal disease.  相似文献   

6.
The tubal tonsil of the horse surrounds the pharyngeal opening of the eustachian tube and is lined by pseudostratified columnar ciliated epithelium interspersed with areas of follicle-associated epithelium (FAE) heavily infiltrated by lymphocytes but devoid of goblet and ciliated cells. Scanning and transmission electron microscopy revealed microvillous cells and cells with features characteristic of M cells such as reduced microvilli or depressed bare surface, more numerous mitochondria, small vesicles and lysosomes, as well as vimentin filaments and epitopes specific for GS 1-B4 as previously seen in the nasopharyngeal tonsil. M cells were also identified in areas of respiratory epithelium not associated with lymphoid follicles and appeared to be the nasal mucosal counterparts of recently described intestinal villous M cells in the mouse. The underlying lymphoid tissue of the FAE was generally organized as solitary lymphoid follicles without germinal centres in contrast to the diffuse and large amount of organized lymphoid follicles with germinal centres that characterize the nasopharyngeal tonsil. CD8+ T and B-lymphocytes were much fewer than in the nasopharyngeal tonsil. High endothelial venules were mainly oriented towards the parafollicular area and contained much fewer endothelial pores and vesiculo-vacuolar organelles. Finally, scattered small clusters of mucus acini and striated muscles were other features that differentiated the tubal and nasopharyngeal tonsils.  相似文献   

7.
The monospecific antibody directed against cytokeratin 18 consistently immunostained microfold cells (M‐cells) in the ileum epithelium of pigs. In adult pigs, M‐cells were numerously distributed in the dome epithelium overlying Peyer's patches, especially in the crypt epithelium to the lower dome epithelium. The M‐cells presented in the crypt epithelium were mostly columnar in shape and showed a gradual transition from columnar cells to pocket‐like cells as they drew near the lower dome epithelium. In contrast, the M‐cells that were sporadically located in the villus epithelium were all columnar and similar to enterocytes in shape. In newborn pigs, a few M‐cells were observed only in the infant dome epithelium, which were all columnar resembling the enterocytes. Of the 19 lectins used, the dome epithelial cells were selectively stained by lectins from Ulex europaeus‐I and Anguuilla anguilla. Especially, the M‐cells were stained by lectin from Anguuilla anguilla although the intensity varied on individual pigs. Lymphoid follicles in the lamina propria were well developed in the adults compared to these in the newborns, and lymphoid cells were more populated in the lower part than the upper part of the dome. The present results provide available information to understand the differentiation and functional heterogeneity of porcine M‐cells.  相似文献   

8.
The small intestines of calves inoculated orally with the enteropathogenic strain of Escherichia coli 0101:K'B41',K99 were examined by electron microscopy at 3, 6, 12, 16, 21, 36, 69, 70 and 72 hours after inoculation. The challenge organism adhered to the mucosa of the distal small intestine from six hours post-inoculation. Bacteria were separated from the microvillous brush border by a gap of 200 to 300 nm in which bacterial fimbriae and the microvillous glycocalyx were seen. Bacteria never were found in epithelial cells but were present in macrophages in the lamina propria from 12 hours. At three and six hours, cytopathic changes were not seen in the small intestine, but from 12 hours epithelial cells on affected villi had blunt and thick microvilli and contained cytoplasmic inclusions. Epithelial cells were seen frequently in the process of extrusion from the villi, either singly, in small groups, or as ribbons of cells. Intervillous bridges, characteristic of villous fusion, were seen frequently from 69 hours.  相似文献   

9.
The follicle-associated epithelium (FAE) of Peyer''s patches (PPs) contains M cells that are important for reducing mucosal immune responses by transporting antigens into the underlying lymphoid tissue. We generated a monoclonal antibody (C6) that reacted with the FAE of calf ileal PPs, and analyzed the characteristics of C6 using immunohistochemistry and Western blotting. FAE of the ileal PP was stained with C6 during both late fetal developmental and postnatal stages. Neither the villous epithelial cell nor intestinal crypt basal cells were stained at any developmental stage. During the prenatal stages, FAE of the jejunal PP was C6-negative. However, a few C6-positive cells were distributed diffusely in some FAE of the jejunal PPs during the postnatal stages. The protein molecular weight of the antigen recognized by C6 was approximately 45 kDa. These data show that C6 is useful for identifying the FAE in ileal PPs and further suggest that differentiation of the FAE in these areas is independent of external antigens.  相似文献   

10.
The infectivity and pathogenicity to newborn pigs of antigenically related coronaviruses from pigs (transmissible gastroenteritis virus; TGEV), cats (feline infectious peritonitis virus; FIPV), and dogs (canine gastroenteritis virus; CGEV) were studied by light, scanning electron, and immunofluorescence microscopy. Hysterectomy-derived, 12-hour-old pigs were orally given tissue culture or frozen preparations of 6 coronavirus strains (3 porcine, 2 feline, and 1 canine). The pigs were killed at regular intervals between 24 and 144 hours after exposure. Virulent TGEV and virulent FIPV produced necrosis of villous epithelium, resulting in villous atrophy in the jejunum and the ileum. Similar, but less extensive and severe lesions, were produced by the 4 other viruses. Coronaviral antigens were identified by immunofluorescence in villous epithelial cells of pigs that had been inoculated with virulent TGEV, attenuated TGEV, virulent FIPV, and tissue culture-adapted FIPV. In contrast, coronaviral antigens were not induced by the small plaque variant TGEV and virulent CGEV in the villous epithelium, but rather in cells of the lamina propria and crypt epithelium.  相似文献   

11.
The association of cryptosporidia with the intestinal epithelium of three neonatal calves was studied by scanning (SEM) and transmission (TEM) electron microscopy. Trophozoites and schizonts were observed embedded in the microvillous brush border of epithelial cells. Merozoites, released from schizonts, were seen free in the lumen and penetrating epithelial cells by SEM and TEM. Incorporation of microvilli into the parasitophorous envelope of trophozoites was seen by TEM. These findings indicate that cryptosporidia develop at an intracellular position in the apex of the epithelial cells following merozoite penetration.  相似文献   

12.
The distribution and diameter of the pores of epithelial basement membrane in the intestinal villi and the lymph nodules of ileal Peyer's patches were investigated in the rat small intestine by scanning electron microscopy after the removal of the overlying epithelial cells with OsO(4) maceration. In the duodenum, jejunum and ileum, the pores were mainly distributed at the upper three fourths of the villi, but were scarce around the top of the villi. The diameter of some of the pores in the upper three fourths of the villi was larger than that of those in the lower portion. The protrusion of lymphocytes and the cytoplasmic processes of macrophages were also seen at the orifices of the pores. In ileal Peyer's patches, in contrast, pores were densely distributed in the lower one third of the follicle-associated epithelium (FAE) where M cells were mainly seen. Furthermore, these pores were larger than those found in the upper two thirds. Lymphocytes or cytoplasmic processes of macrophages were frequently seen in the lower one third of FAE. These results suggest that the pores at the basement membrane correspond to the passage of the immunocompetent cells which are in contact with M cells or villous columnar epithelial cells and that the abundance of pores is a sign of aggressive interaction between the particular epithelial cells and the immunocompetent cells at the upper three fourths of intestinal villi and the lower one third of FAE in the rat small intestine.  相似文献   

13.
The ultrastructure of epithelial responses against the membrane adhesion of indigenous bacteria was investigated in the follicle-associated epithelium (FAE) of rat small intestine. The most frequent adherence of the various morphological types of bacteria to the epithelial membranes was found at the apex of the FAE. The attachment sites were deeply invaginated, and their bottoms were deformed into a sharp cone shape. Four layers with different electron densities were formed just beneath the apical membranes by microfilaments which surrounded the invaginations. The electron density of each layer was gradually decreased as being apart from the invaginations. The extremities of some bacteria in the invaginations were deformed into sharpened shapes. The cell walls of the extremities of the bacteria were occasionally dissolved in the invaginations, and their cytoplasms were slightly swollen with low electron densities. In some invaginations, the attached bacteria were eliminated to leave their fragments such as filamentous debris and a part of cell walls. Finally these remnants disappeared completely. When the bacterial colonies existed in the middle region of the FAE, the attachment of bacteria resulted in the engulfment of bacteria by M cells. The degenerated bacteria whose cytoplasmic matrices were separated into high electron dense materials and cleared materials were occasionally engulfed by ordinary microvillous columnar epithelial cells or goblet cells throughout the FAE. These findings suggest that the epithelial cells reject the attachment of live indigenous bacteria and that the M cells absorb indigenous bacteria in rat Peyer's patches.  相似文献   

14.
The mucous membrane of the caecum and colon ascendens of adult horses was first studied using light and transmission electron microscopy. In the surface epithelium there was an inconspicuous constellation of organelles, otherwise there was a lot of mitochondria as a source of energy for absorptive performances. Moreover, enlarged intercellular spaces exist as an indication of an increased uptake of water and electrolytes. In the basal region of Lieberkühn's crypts there were single enteroendocrine cells and numerous granules in the apical epithelial cytoplasm. The functional meaning of these granules is contrarily discussed in the literature. There was no epithelial activity of alkaline phosphatase. Against that a small positive reaction of adenosine triphosphatase was observed at the lateral plasmalemata of the epithelial cells. The sense of these findings with regard to the transport of substances in the equine large intestine is discussed.  相似文献   

15.
The ultrastructure of the surface epithelium and tubular glands of the uterus in the immature ostrich is described. In ostriches with inactive ovaries the uterus is lined by a non-ciliated simple columnar epithelium, with basally located heterochromatic nuclei. Scanning electron microscopy revealed that these non-ciliated cells have a dense microvillous cover. A simple columnar to pseudostratified columnar epithelium, comprised of non-ciliated and ciliated cells, lines the uterus in birds with active ovaries. The ciliated cells possess a wide luminal region, which contains a nucleus and various organelles. An accumulation of secretory granules was observed in the apical regions of the non-ciliated cells, as well as in a few ciliated cells. In addition to non-ciliated and ciliated cells, a cell type with rarefied cytoplasm was also identified. These cells appear to correspond to calcium secreting cells identified in other avian species. The results of this study indicate that, although uterine differentiation is present in immature ostriches with active ovaries, the production of secretory product appears to occur mainly in non-ciliated epithelial cells.  相似文献   

16.
Hyaluronan is involved in fundamental reproductive events such as sperm storage in the female reproductive tract, fertilization, and early embryo development, these functions are presumably mediated by its major cell surface receptor, CD44. The present study was conducted to investigate the presence and localization of CD44 in the bovine oviductal epithelium, using immunohistochemical and Western blot methods on tissue sections and epithelial cell extracts collected from the uterotubal junction (UTJ), isthmus, and ampulla of animals in the oestrus or luteal phase of the oestrous cycle. While positive immunolabelling for CD44 was found on the ad-luminal surface and supra-nuclear region of epithelial cells in all tubal segments investigated, in the UTJ, there were epithelial cells in which the entire cytoplasm positively stained. We found no differences in terms of CD44-positive staining between the different stages of the oestrous cycle. Presence of CD44 was detected by Western blotting in the tubal epithelium as a single band at 200 kDa. Although it appeared in all tubal segments, the expression of CD44 protein was more accentuated in the sperm reservoir (UTJ) than in the other segments. This is the first time CD44 has been detected in the epithelium of the tubal sperm reservoir in cattle, suggesting a pathway for the action of hyaluronan in this segment.  相似文献   

17.
Uptake of macromolecules (e.g., ferritin) by M cells in follicle-associated epithelium in small and large intestine was investigated in three healthy, conventionally raised, 2- to 3-week-old, female Holstein Frisian calves. A 2.5% solution of ferritin was injected into the ligated loops in mid-jejunum, in terminal ileum, in the ascending colon adjacent to the ileocecal junction, and in the proximal loop of the ascending colon containing gut-associated lymphoid tissue. After exposure times that ranged from 82 to 165 minutes, ferritin was detected in M cells of domes in the small intestine, as well as in cells in follicle-associated epithelium of proprial lymphoid nodules and lymphoglandular complexes of colon that morphologically resembled M cells of small intestine. Ferritin was found in apical invaginations, apical vesicles, multivesicular bodies, basal vesicles, and adjacent intercellular spaces. In addition to ferritin, apical vesicles, multivesicular bodies, and intercellular spaces contained 50-nm membrane-bound particles. More ferritin was endocytosed by M cells of the small intestine than by M cells of the large intestine. In the large intestine, higher amounts of ferritin were found in M cells of follicle-associated epithelium overlying proprial lymphoid nodules than in M cells of follicle-associated epithelium in the depth of lymphoglandular complexes. Based on these results, we concluded that M cells of follicle-associated epithelium in the colon of calves provide a route for antigen uptake into the intestinal lymphoid system.  相似文献   

18.
Nitric oxide (NO) is a free radical and produced from L-arginine by nitric oxide synthase (NOS). Since NO is recently suggested to be involved in olfactory perception, the expression of eNOS, an isoform of NOS, was examined in the rat olfactory epithelium. The activity of NADPH-diaphorase was also examined as a marker of NOS. In the dorsomedial region of the nasal cavity, intensely positive reactions for NADPH-diaphorase were observed in the entire cytoplasm of sensory cells (olfactory cells). By immunohistochemistry, intensely positive reactions for eNOS were also found in the dorsomedial region of the nasal cavity. These reactions were observed on the free border of the olfactory epithelium. By immunoelectron microscopy, positive reactions for eNOS were found in the cilia of olfactory cells. In addition, in situ hybridization analysis of the olfactory epithelium revealed the expression of eNOS mRNA in the olfactory cells. These results indicate the presence of eNOS in the olfactory cells of the rat, and differential expression of eNOS in the olfactory epithelium depending on the regions of the nasal cavity. In addition, NO produced by eNOS may be involved in olfactory perception in the cilia of olfactory cells.  相似文献   

19.
The first lysosomes appear in the stratified embryonic intestinal epithelium during its transition into the simple columnar form. This occurs concurrently with the initial villogenesis. Lysosomes situated basally in the epithelium are presumably the precursor of the first giant lysosomes in the lower small intestine of rodents. Immediately after establishment of the simple configuration a special form of secondary lysosomes can be observed, i.e. glycogenosomes, in the ephemerally existing huge glycogen containing areas. During subsequent fetal intestinal development one observes two events in the epithelial cells, which are the same in principle but differ in one essential point, while they exhibit partially impressive structures. On the one hand there are autophagic degenerative lysosomal processes in the villous epithelium until birth, that lead to a surface without villi in the large intestine, where they occur particularly frequently. On the other hand giant lysosomes originate perinatally in the lower small intestine as well as in the caecum and colon ascendens, in which protein molecules, which were transported by a system of inframicrovillar membranes, are lysosomally degraded, which can be defined as a heterophagic event.  相似文献   

20.
Culture supernates from two strains of E. coli were placed into different ligated intestinal sections (loops) of each animal. The two bacterial strains were identical except that one contained a plasmid carrying the heat-stable toxin b (STb) gene, while the other did not. Morphometric techniques were used to assess villous epithelial surface areas and mucosal volumes in both intestinal segments exposed to STb-positive (test) and to STb-negative (control) supernates. In pigs whose intestines were exposed to STb-positive supernatants for 2 hours, both villous epithelial surface area and mucosal volume were significantly smaller in test loops than in control loops (P less than 0.02). In test loops of pigs incubated for 1 hour, and in test loops of lambs incubated for 2 hours, there was a decrease in villous epithelial surface area which approached the test for significance but did not meet it (0.05 less than P less than 0.10). Rabbit test loops did not differ from rabbit control loops in either villous epithelial surface area or mucosal volume. Histological examination of the tissues from all three species revealed epithelial changes in porcine and ovine tissues only. In porcine and ovine tissues, epithelium at villous tips was seen to be cuboidal or squamous, or even to be absent. Villi with similarly altered epithelium were seen in control loops, but were seen much more frequently in test loops. These epithelial changes were seen as early as 30 minutes of incubation in pigs. Intestinal tissues from these pigs were examined by transmission electron microscopy, but no difference between test and control tissues was seen.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

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