Microvillous Epithelial Cells Research Articles

Prosaposin in the rat oviductal epithelial cells.

Prosaposin (PSAP) has two forms: a precursor and a secreted form. The secreted form has neurotrophic, myelinotrophic, and myotrophic properties. The precursor form is a precursor protein of saposins A-D. Although the distribution of PSAP in male reproductive organs is well known, its distribution in female reproductive organs, especially in the oviduct, is unclear. Immunoblots and immunohistochemistry of oviducts showed that oviductal tissues contain PSAP proteins, and a significant increase in PSAP was observed in the estrus-metestrus phase compared to the diestrus-proestrus phase in the ampulla. To identify PSAP trafficking in cells, double-immunostaining was performed with antibodies against PSAP in combination with sortilin, mannose 6 phosphate receptor (M6PR), or low-density lipoprotein receptor-related protein 1 (LRP1). PSAP and sortilin double-positive reactions were observed near the nuclei, as well as in the apical portion of microvillous epithelial cells, whereas these reactions were only observed near the nuclei of ciliated epithelial cells. PSAP and M6PR double-positive reactions were observed near the nuclei of microvillous and ciliated epithelial cells. PSAP and M6PR double-positive reactions were also observed in the apical portion of microvillous epithelial cells. PSAP and LRP1 double-positive reactions were observed in the plasma membrane and apical portion of both microvillous and ciliated epithelial cells. Immunoelectron staining revealed PSAP immunoreactive small vesicles with exocytotic features at the apical portion of microvillous epithelial cells. These findings suggest that PSAP is present in the oviductal epithelium and has a pivotal role during pregnancy in providing an optimal environment for gametes and/or sperm in the ampulla.

Gross and Microanatomical Studies on the Uterus of Japanese Quail (Coturnix japonica) During the Post-hatching Period with Special Emphasis on Sperm Host Gland

The quail acts as a model for recent experimental studies and its oviduct development is of special interest. This study was carried out on 61 adult female Japanese Quail (Coturnix japonica) collected from quail farms in Assiut and South Valley Universities in order to characterize the morphological features of the uterus during the post-hatching life. The process of development was consisted of three stages: undifferentiated, differentiated and adult stage. The undifferentiated stage began from day of hatching till 25-days old age and the oviduct was divided into cranial, middle and caudal parts. The caudal part (the future uterus and vagina) was represented by a simple wall of a single layer of simple columnar epithelial cells resting on subepithelial undifferentiated mesenchymal cells with many mitotic divisions. At 20 days old, the mucosa is thrown into distinct mucosal folds as well as the ciliated and secretory epithelial cells were first appeared at this age. At differentiated stage (from 30-40 days), the tubular glands began to develop and opened between the epithelial cells. The adult stage began from 50 days old and the luminal surface of the uterus was characterized by numerous long leaf-like folds. Also, the apical part of the cells showed positive reaction with PAS and Alcian blue. The tubular glands are filled with the secretion, which give positive reaction with PAS and Alcian blue. The uterovaginal junction lies between the uterus and the cranial part of the vagina, and contains the sperm host gland. This area showed transition of the mucosal folds from longitudinal folds of the uterus to complex interconnecting folds of the vagina. Many typical sperms with oval head and tail were inserted between the ciliated and microvillous surface epithelial cells of sperm host glands. This detailed anatomical and histological study of post-hatching development of uterus in quail will not only help to evaluate changes occurs during this critical period, but also will assist in understanding clearly the physiology of reproduction in quail.

Evidence of LAT1 expression in canine caput epididymis.

L-type amino acid transporter 1 (LAT1), the first isotype of amino acid transport system L, transports aromatic and branched amino acids pivotal for fundamental cellular activities such cellular growth and proliferation. LAT1 expression was high only in the brain in contrast to its limited distribution and low level of expression in normal tissues. We found potent LAT1 expression in canine caput epididymis by quantitative RT-PCR and Western blotting analysis. Immnuno-histochemical examination revealed observable LAT1 in microvillous epithelial cells.

Ultrastructural Study on the Differentiation and the Fate of M cells in Follicle-Associated Epithelium of Rat Peyer's Patch

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.

Differences in Lectin-Binding Properties between the Common Mucosal Epithelium and Follicle-Associated Epithelium in the Rabbit Small Intestine

Differences in sugar distribution between the villous epithelium and follicle-associated epithelium (FAE) were compared using lectins in the rabbit small intestine. In every portion, villous columnar epithelial cells primarily exhibited a positive reaction to the GalNAc, GlcNAc, galactose, and oligosaccharide. In the ileal Peyer's patch (PP), whereas microvillous epithelial cells exhibited positive reactions, M cells tended to be negative. The villous epithelial reaction to the fucose group was negative, but M cells and microvillous epithelial cells showed a positive to the fucose. No epithelium had a positive reaction to the mannose and glucose. The variety of lectin-binding properties of villous epithelial cells and M cells may reflect specificity for the recognizing luminal substances such as antigenic molecules and bacterial elements.

Immunohistochemical Study on the Delayed Progression of Epithelial Apoptosis in Follicle-Associated Epithelium of Rat Peyer's Patch

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.

Cellular kinetics of villous epithelial cells and m cells in rabbit small intestine.

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.

The cellular differentiation of M cells from crypt undifferentiated epithelial cells into microvillous epithelial cells in follicle-associated epithelia of chicken cecal tonsils.

To clarify the cellular origin and the fate of M cells, detailed distributions of the epithelial cells were investigated scanning electron microscopically on the follicle-associated epithelia (FAE) of chicken cecal tonsils. The distribution of M cells was closely related with the situation of the crypt orifices in chicken cecal tonsils. In undeveloped cecal tonsils, the intestinal crypts were localized at the periphery of the FAE. In these tonsils, M cells without microvilli (M(0)) were predominantly populated in the basal region of the FAE, whereas goblet cells and microvillous epithelial cells (MV) were more distributed in the middle to the apical region of the FAE. A few M cells with short microvilli were dispersed throughout the FAE. Significantly shrunk MV (MVs) clustered together in transitional portions from the lateral face to the roof of the FAE. In well-developed cecal tonsils, the crypts also opened at the lateral surface in addition to the periphery of the FAE. In these tonsils, the M(0) accumulated densely in the small areas around the crypt orifices exclusively. No sign of exfoliation of apoptotic epithelial cells was found in the M(0)-accumulated areas and at their peripheral boundaries. The MVs were often clustered in the central regions among the crypt orifices in addition to the roof of the FAE. These findings suggest that M cells are directly derived from the undifferentiated crypt epithelial cells, not fall into apoptotic cell death and further differentiate into MV in the FAE of chicken cecal tonsils.

Ultrastructural characteristics and lectin‐binding properties of M cells in the follicle‐associated epithelium of chicken caecal tonsils

To clarify the nature of M cells, the detailed ultrastructural characteristics and lectin-binding properties of M cells were investigated in follicle-associated epithelium (FAE) of chicken caecal tonsils. M cells presented various outlines from columnar to dome shaped. Their polymorphism was dependent on the number of harboured intraepithelial migrating cells. The lighter and larger nuclei of M cells were situated at more apical levels in the epithelial lining compared with those of neighbouring microvillous epithelial cells. The microvilli, which were significantly shorter and thicker than those of adjacent microvillous epithelial cells, were sparsely distributed or completely absent on the apical surfaces of M cells. In general, the apical cytoplasm of M cells without microvilli protruded slightly into the intestinal lumen. Numerous small vesicles were often contained in the apical cytoplasm. The numerous small invaginations of the apical and lateral cell surfaces suggested active transportation of luminal substances. No canaliculi existed in the apical cytoplasm of M cells whereas they were often detected in the neighbouring microvillous epithelial cells. A noteworthy finding was the frequent detection of multivesicular bodies in the apical cytoplasm of M cells. These multivesicular bodies suggest some degradation of ingested luminal substances during transcytoplasmic transportation. WGA and 4 other lectins strongly reacted with all epithelial cells except for M cells, this negativity suggesting a means of detecting M cells in chicken caecal tonsils. Three lectins, DSL, ConA and Jacalin, reacted weakly with the glycocalyx on M cells. The positive reactivity might allow chicken M cells to be utilised for specific antigen delivery into the mucosal immune system in some parenteral vaccinations.

Apoptosis of villous epithelial cells and follicle-associated epithelial cells in chicken cecum.

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.

Proliferation and cellular kinetics of villous epithelial cells and M cells in the chicken caecum.

The proliferation sites and cellular kinetics of villous epithelial cells and M cells in the intestine of the adult chicken have never been clarified. In this study, we determined the proliferation sites in the chicken caecum using colchicine treatment and detection of proliferative cell nuclear antigen (PCNA). The cellular kinetics of these cells were also studied using bromodeoxyuridine (BrdU) as a tracer. Enterocytes in their mitotic period were observed along the entire length of the intestinal crypt of the caecum, with a denser distribution in the middle portion of the crypt, except for the caecal tonsil. The centres of distributions were at 49% of the distance from the bottom of the crypt in the base and 41% in the apex of the caecum. In the caecal tonsil, the centres of distributions were at 64% in the long type of crypt from the bottom of the crypt and at 44% in the short type of crypt. On the other hand, the PCNA-positive enterocytes were distributed more densely at the bottom of the crypt, except for the caecal tonsil. The centres of distributions were at 36% in the base from the bottom of the crypt, 37% in the body, and 34% in the apex. In the caecal tonsil, they were at 54% in the long type of crypt and 44% in the short type. The BrdU-labelled enterocytes reached to the basement of the intestinal villi in all caecal portions at 1 d after the BrdU administration. The leading edge of the labelled enterocytes disappeared from the villous tips at 4 d in the base and the body and 3 d in the apex. In the caecal tonsil, the BrdU-labelled microvillous epithelial cells and the M cells appeared near the orifice of the crypt at 1 d, and BrdU-labelled M cells were not observed in the crypt. Thereafter, almost all of these cells disappeared at 5 d from the follicle associated epithelium (FAE). These results suggest that M cells are transformed from their precursors within 1 d, and the turnover time for M cells occurs within 4 d after the cell division of the precursors.

Membrane proteins and enzymes of Leishmania.

Leishmania are kinetoplastid protozoan parasites responsible for a spectrum of zoonotic, and less commonly anthroponotic, diseases of man and other mammals. The parasite is transmitted by a blood-feeding dipteran vector of the subfamily Phlebotominae, and undergoes radical morphological and metabolic changes as it passes from the insect vector to the mammalian host. In the latter, it is found as an obligately intracellular, small oval cell, 2–3 μm in diameter, with a truncated flagellum that barely extends beyond the plasma membrane. The intracellular, or amastigote, stage of the parasite specifically infects cells of the mononuclear phagocyte system, in which it lives and divides within the acidified phagolysosomes at pH 4.7-5.3 (Antoine et al., 1990). The parasites disseminate within the mammal as amastigotes, released as a result of the destruction of the host cell, and are bound and engulfed by neighboring uninfected macrophages. Transmission from one mammal to another occurs through the sandfly vector: amastigotes within mononuclear cells are ingested during the blood meal of the female sandfly and differentiate within the presumably neutral-to-alkaline environment of the sandfly midgut to form elongated, motile, flagellate cells called promastigotes, which are 12–16 μm long and 1.5–3.5 μm wide. The promastigotes remain free in the midgut lumen or attach by means of their flagella to the microvillous epithelial cells of the insect midgut. The parasites divide actively, then colonize the chitinous foregut of the insect, where the morphologically distinct paramastigotes adhere by means of hemidesmosomes at the tips of their modified flagella (Killick-Kendrick et al., 1974; reviewed in Molyneux and Killick-Kendrick, 1987).

Expression of a secretory product by microvillous and ciliated cells of the human endometrial epithelium in vivo and in vitro.

A monoclonal antibody which identifies a component of post-ovulatory endometrial secretions is now shown to be expressed within the cytoplasm and on the cell surface of both microvillous and ciliated epithelial cells. A glandular explantation model was developed in order to study the 'carry over' of this secretion to the regenerative phase endometrium. A loss of cytoplasmic antigen was observed in vitro. However, it was retained on the cell surface in a fashion consistent with its expression at the time of explantation. Mosaicism of expression of this secretory component occurs throughout the secretory-phase and is particularly pronounced at the time of transition from proliferative to secretory phase. It is concluded that both ciliated and microvillous epithelial cells produce a post-ovulatory secretory component which may be retained on the cell surface in the absence of hormonal stimulation.

Scanning electron microscopy of the gills of a freshwater catfish,Rita Rita

Variations in the gross morphology and surface architecture of the gill filaments and secondary lamellae of a freshwater catfish (Rita rita) have been investigated using scanning electron microscopy. Heterogeneity of the gill has been correlated with the distribution of lamellar water-flow at different regions of a gill filament. Higher lamellar water flow (cc/pore/cmH2O/sec) was estimated for the middle region of the filaments. The filaments are covered with epithelial cells whose surface is provided with well-developed microridges. The lamellae are generally covered with microvillous epithelial cells. The variations in surface architecture of the gill filaments and secondary lamellae have been correlated with their probable functions.

Adenoid cystic carcinoma of the breast.

The clinical, histologic, cytologic, and ultrastructural features of three adenoid cystic carcinomas of the breast are presented. All three neoplasms occurred in postmenopausal women. One patient was treated by wide re-excision of the biopsy site. Two were treated by modified radical mastectomy; no axillary lymph node metastases were found. None of the neoplasms has recurred. Neither estrogen nor progesterone receptors were detected in any of the neoplasms. The histopathologic criteria for the diagnosis of adenoid cystic carcinoma are described, and the differential diagnosis is discussed. Since the cytopathologic features of adenoid cystic carcinoma of the breast appear to be distinctive, the neoplasm can be diagnosed by fine-needle aspiration based upon the presence of the following features: 1) a cellular smear; 2) a uniform population of small, basaloid tumor cells; and 3) small globules of mucoid material surrounded by a rim of neoplastic cells. Ultrastructurally, the predominant cell type has the appearance of a modified myoepithelial cell, but true lumina lined by microvillous epithelial cells are also present. The ultrastructural findings are consistent with the proliferation of neoplastic cells that have the capacity to produce all of the epithelial elements of the breast, i.e., ductal, acinar, and myoepithelial, and so recapitulate the complete ductal or acinar unit.

Experimental study of human tracheal heterografts in pigs

In 12 three-months-old pigs a window-shaped tracheal defect was made and the defect closed by a precisely fitting Cialit-fixed, human tracheal heterograft. The macroscopic, microscopic, scanning and transmission electron microscopic investigation of the grafted area revealed that the tracheal epithelium was formed by microvillous epithelial cells primarily. 3 months after grafting cartilage of the tracheal transplant survived but after 9 months was replaced by a tight scar. The connective tissue plate thus formed was sufficiently stable to maintain normal respiration in the pigs.

Inner surface ultrastructure of the lungs of frog and lizard

Mammalian lung cells and tissues have been studied extensively, resulting in a voluminous literature. In comparison, the ultrastructure study of the respiratory systems of the lower vertebrates is incomplete. Lung surfactant and the related osmiophilic lamellar inclusions were observed in bird lung by Lambson and Cohn and in cultured frog lung cells by Soloff and Burns. This report compares the inner surface structure, cell types and vascularization in the lungs of frog and lizard.Mature Rana pipiens and Lacerta viviparus lungs were fixed at normal volumes (approximately 0. 3 ml and 0. 05 ml, respectively) with cacodylate-buffered glutaraldehyde, post-fixed with OsO4 and processed for both TEM and SEM.Frog LungLooking outward from the central duct, the septa divide the respiratory regions into smaller and smaller compartments, ending in closed sacs or alveoli, ranging from 150 to 300 mμ in diameter (Fig. 1). The largest or primary septa are covered by ciliated epithelium, whereas a squamous microvillous epithelium covers the minor septa and alveolar walls (Fig. 2). In section, the microvillous epithelial cells appear as a combination of type 1 and type 2 alveolar epithelial cells of the mammalian lung. Capillaries appeared as a random network through the septa and alveolar walls.

EXTRA-ECTODERMAL STRANDS IN THE CILIATED BANDS OF THE ECHINOPLUTEUS.

An ectodermal nerve net and some extra-ectodermal, axon-like elements have been demonstrated in the ciliated bands of Psammechinus miliaris larvae. It is proposed that these extraectodermal structures, together with the microvillous epithelial cells and the ectodermal nerves, participate in the co-ordination of responses on sensory stimulation from the outside of the larvae.

Ultrastructure of the tube foot wall of a regular echinoid, Diadema antillarum Philippi.

An ultrastructural study of the tube foot wall of a regular echinoid,Diadema antillarum, was made. Ciliated microvillous epithelial cells, their inclusions, amoebocytes, and the arrangement of collagen and muscle in the tube feet are described. The neuropile, together with its vesicular components and possible neurosecretory elements, is considered and discussed as are connective tissue bridges across the lumen. Consideration is given to possible functions for the various components of the tube foot.