Showing papers on "Apical cytoplasm published in 1996"

Development of the olfactory epithelium and vomeronasal organ in the Japanese reddish frog, Rana japonica.

Abstract: Histological and ultrastructural development of the olfactory epithelium (OE) and vomeronasal organ (VNO) was investigated in the Japanese reddish frog, Rana japonica. Tadpoles, from hatching to the end of metamorphosis, and adult frogs were examined. In the adult, olfactory cells of the OE were equipped with olfactory vesicles with long cilia, but supporting cells with microvilli. The supporting cells of the OE contained secretory granules, PAS-positive by light microscopy, in their apical cytoplasm. On the contrary, sensory cells of the VNO were equipped with microvilli, and supporting cells of the VNO were equipped with cilia, but without secretory granules. Embryologically, the olfactory cells were indistinguishable from the supporting cells in the olfactory placode (primitive OE) lining the nasal pit, at hatch. The VNO appeared as a concave of the ventral part of the OE at 4 days after hatch. At this time, the olfactory and supporting cells of the OE became distinguishable from each other. Secretory granules were formed in the supporting cells of the OE at 36 days after hatch, and the OE was similar in fine structure to that in the adult. While, the VNO remained immature at 24-36 days after hatch, and did not complete its ultrastructural development at 60 days after hatch, the end of metamorphosis. These findings suggest that the OE may take part in the olfaction earlier than the VNO in ontogeny.

Sertoliform endometrial adenocarcinoma: a study of four cases.

Abstract: We studied four endometrial carcinomas with a conspicuous component that resembled patterns in Sertoli cell tumors. The patients presented at age 44-83 years (mean 65 years), with abnormal or postmenopausal vaginal bleeding in three and abnormal cervical cytology in one. All were multiparous, moderately to markedly obese, and hypertensive, and three patients had non-insulin-dependent diabetes mellitus. One tumor was suspected to be an endometrial stromal sarcoma with sex-cord-like differentiation on biopsy. Gross examination of the hysterectomy and bilateral salpingo-oophorectomy specimens showed solid polypoid endometrial tumors in each case. Light microscopic examination showed three to be superficially invasive of the myometrium and one to be confined to the endometrium; none of the tumors showed the tongue-like pattern of myoinvasion or the angiolymphatic invasion characteristic of low-grade endometrial stromal sarcomas. The sertoliform component, which predominated in one case and was only focal in the three others, was composed of uniform small hollow tubules lined by columnar cells with apical cytoplasm and of compact slender cords. The tubules and cords were often present between benign-appearing or carcinomatous glands. In the case with predominate sertoliform areas, the lesional cells had clear cytoplasm suggesting a lipid-rich variant; special stains of this case demonstrated cytoplasmic glycogen but no fat. In none of the cases was cytoplasmic mucin, argyrophil granules, or argentaffinity demonstrated. The nonsertoliform areas of the tumors consisted of typical endometrioid adenocarcinoma; concurrent endometrial hyperplasia was also present in each case. Squamous differentiation and minor foci of anaplastic carcinoma with bizarre tumor giant cells were present in three tumors. Immunoperoxidase stains showed staining for two or more markers of epithelial or glandular differentiation in the sertoliform areas in all cases (keratin, epithelial membrane antigen, carcinoembryonic antigen, CA125, Tag72), with focal expression of vimentin in all cases. In none of the cases was desmin or actin staining observed. The evidence indicates that tumors in this series are variants of endometrioid adenocarcinoma and are distinct from uterine tumors resembling ovarian sex-cord tumors and stromal sarcomas with sex-cord-like differentiation.

Studies of the Choroid Plexus and Its Associated Epiplexus Cells in the Lateral Ventricles of Rats Following an Exposure to a Single Non-Penetrative Blast.

Abstract: The choroid plexus in rats exhibited ultrastructural changes following a non-penetrative blast. The immunophenotypic features of epiplexus cells associated with the choroid plexus epithelium were also altered. In rats killed at 1 and 7 days after the blast, the intercellular spaces between the epithelial cells were greatly widened, coupled with the massive eruption and possible extrusion of the apical cytoplasm into the ventricular lumen. Associated with these changes was the passage of some monocytes/lymphocytes across the epithelium. The incidence of such a migratory phenomenon was more frequent in rats killed 7 days after the blast. In rats killed 14 days after the blast, the ultrastructural changes of the epithelial cells became less pronounced. At 21 and 28 days after the blast, the ultrastructure of the choroid plexus was comparable to that of normal specimens. The immunoreactivity of epiplexus cells in terms of their cell number and staining intensity with the monoclonal antibodies OX-42, OX-18, OX-6 and ED1 was noticeably augmented at 7 and 14 days after the blast; this, however subsided at 21 and 28 days. It is concluded that the choroid plexus is extremely sensitive to a blast wave as manifested by its structural alterations and the vigorous expression of CR3 receptors and MHC antigens by the epiplexus cells. It is suggested that a possible immune response might have been triggered in the cerebrospinal fluid ventricular system following the blast.

Ultrastructural analysis of the integument during the moult cycle in Ligia italica (Crustacea, Isopoda)

Abstract: The formation of the cuticle was investigated during moulting of the isopod crustaceanLigia italica. The intermoult cuticle is a four-layered lamellar structure composed of chitin-protein fibrils and mineralized in its upper half. The distribution of calcium carbonate in cuticle during moult cycle was determined by cytochemical methods and X-ray microanalysis. Epi-and exocuticle are secreted during premoult. Calcium is resorbed from the old cuticle and accumulates in the ecdysal gap as calcium granules. Endocuticle is secreted after moult when the mineralization of exocuticle starts. The shape and ultrastructure of epithelial cells change during cuticle secretion and mineralization. Mitochondria, bundles of filaments, calcium granules and large amounts of glycogen accumulate in the apical cytoplasm of cells in premoult animals.

Chloride secretion in the submandibular gland of adult and early postnatal rats studied by X-ray microanalysis

Abstract: Submandibular acinar cells of 1-day-old, 7-day-old, and adult rats were analyzed with X-ray microanalysis after stimulation with carbachol for different time periods (2–7 min). In unstimulated animals, marked differences in elemental content between compartments could be observed: secretory granules had a higher Ca and lower P and K content than other cell compartments. Comparison between different age groups showed significant differences for Ca, which increased with age in all compartments; Mg increased with age in the secretory granules and the apical cytoplasm. Only the glands from adult animals showed a significant effect of cholinergic stimulation: a transient decrease in Cl and K. The Cl concentration in the secretory granules decreased to 60% of the control value, which suggests that the granules release Cl upon stimulation. In young animals, no or little change in elemental distribution was observed after stimulation. This may indicate that Cl-secretion mechanisms are much less prominent in young animals. The ultrastructure of submandibular secretory granules depends on the preparation method: condensed and electrondense in freeze-substituted unfixed tissue, decondensed and more translucent in aldehyde-fixed tissue. This may indicate that the granules can transport water, and swell during the process of aldehyde fixation.

Tuft cells in the main excretory duct epithelia of the three major rat salivary glands.

Abstract: We report the tuft cells in the main excretory duct epithelia of rat salivary glands. These cells exhibit similar fundamental characteristics in the salivary glands and in other organs. However, numerous membrane-bound electron-dense granules are present among the microvilli of the tuft cells in the submandibular gland, but not in other organs. The apical cytoplasm contains numerous vesicles with a filamentous substance that reacts positively for glycoconjugates. The vesicles frequently are close to the apical plasma membrane and seem to open into the lumen. Nerve endings with synaptic vesicles are seen close to the basal portion of the tuft cells. The ratio of the tuft cells to principal cells is highest in the submandibular gland and lowest in the sublingual gland. The functions of the tuft cells in the salivary glands are suggested to be secretion, absorption, and reception.

Further data on intracellular structures of human salivary glands. A SEM study.

Abstract: Specimens of human salivary glands have been studied by our modification of the AODO maceration method which, carried out on sections of controlled thickness, allows the analytical study of human bioptical material. Lately, our technique has been further improved and simplified by omitting the treatment with dimethylsulfoxide and by using osmium-ferrocyanide as secondary fixative. Following maceration with diluted OsO4, some of the sections also were shaken for 10-15 min with a rotating agitator. Already at low magnification, all parenchymal cells were clearly distinguishable for their complement of cytoplasmic organelles. Serous cells and mucous cells at the beginning of their secretory cycle were characterized by well developed RER and Golgi apparatus, while mature mucous cells exhibited only scanty organelles compressed among the secretory droplets. Mitochondria were tubular, and often branched and convoluted. When sectioned, these organelles, besides the usual plate-like cristae, showed tubular cristae as well. The SER of striated and excretory duct cells was well developed and consisted of a network of smooth anastomosing tubules in the apical cytoplasm where it probably represented the transcellular pathway for ion transport. In specimens subjected to shaking, cytoplasmic organelles were occasionally removed allowing a nonobstructed view of the inner side of the plasmalemma and its specializations. With this technique the intercellular canaliculi of serous cells also became appreciable from their cytoplasmic side. They appeared as ribbon-like irregular protrusions with walls fenestrated by holes, corresponding to the interior of microvilli deprived of the cytoskeleton, and, sometimes, with lateral expansions possibly related to the mechanism of exocytosis. Results reported here clearly showed the usefulness of the maceration method in providing additional data on the cytoarchitecture of epithelial cells of salivary glands. Furthermore, by allowing the visualization of internal surfaces previously hidden to direct inspection, our technique may open new horizons in morpho/functional studies of human salivary glands.

Electron microscopic study of the morphological changes of gastric mucous cell induced by Helicobacter pylori in human gastric ulcers.

Abstract: Specimens from 8 cases of human gastric ulcers infected with H. pylori, 3 cases of gastric ulcers without H. pylori infection and mucosal specimens infected with H. pylori from 3 cases of early gastric cancers obtained at surgery were studied by transmission electron microscopy. In the surrounding epithelium of the ulcer, when present, the bacteria were preferentially located at the luminal side of the apical junctional complexes. This was accompanied by dome-like bulging of the apical cytoplasm, but the epithelial continuity was maintained. A consistent finding was the apocrine-like release of the apical cytoplasm into the lumen. In addition, there were cells with marked apical protrusions and cells with dissolution of mucous granules. Degenerative changes, such as cellular edema, vacuole formation and disruption of cell membrane were also observed. The cells which had shed their apical mucous area appeared to degenerate causing massive cell exfoliation and formation of denuded lamina propria. Similar changes of the surface mucous cells were observed in the mucosal specimens infected with H. pylori obtained from early gastric cancers, but such cell pathology was scarce in samples of the gastric ulcers without H. pylori infection. In some ulcers infected with H. pylori, the bacteria were also observed on the surface of the regenerating epithelial cells at the ulcer base. These findings suggest that H. pylori infection is an important factor in the development of gastric ulcers and in the prevention or delay in ulcer healing.

Ultrastructure of cell renewal in the midgut of termites

Abstract: The individual cells of most tissues of an organism have a shorter life span than the organism itself. So, in order to maintain the organism’s integrity, a certain degree of cellular substitution must occur during life. Generally the substitution occurs by steam cells division, but in insects, mitosis is absent or is very rare in adulthood. In these cases a certain amount of undifferentiated cells are responsible for the replacement of the worn ones. The insects midgut is an example of this late condition. At least two types of cells are present in the adult: (1) the digestive, functional or differentiated cells and (2) the generative or undifferentiated cells (HL House 1965 In M Rockstein The Physiology of Insecta, vol. II, Academic Press, N.Y.) In the termites midgut the digestive cells are columnar and present short microvilli in the apical pole, supported by a microfibrilar cytoskeleton which continues into the terminal network (Fig. 1). Usually they have many folds of the plasmic membrane associated with mitochondria on the basal pole (Fig. 1). As these cells age, some deterioration may be observed, mainly in the apical zone. The aging of the cells is characterized by the loss of electron-density of the apical cytoplasm besides the appearance of large autophagic vacuoles and myelin figures (Figs 1, 2). The generative cells form nests inside the functional epithelium. The cells, in the nests sit over the epithelial basal lamina, but do not emerge into the epithelial surface. These cells are always differentiating since a digestive cell needs to be replaced. Then, they are transformed into functional or digestive ones. The process is marked by a straightening of some of the outer cells of the nest, by the development of their organelles, by the production of microvilli in the luminal surface and by appearance of invaginations of the plasmic membrane in the basal surface. In the replacement process, the cellular contacts between the digestive cells apparently become weak and the intercellular space appears enlarged. The damaged digestive cells are pushed up by the unclasping of the generative cells and are seen displayed parallel to the epithelial surface (Fig. 2) before being eliminated into the lumen. The cells undertaking the elimination process have nuclei parallel to the surface, desorganized microvilli (Figs 3, 4) and several types of autophagic structures, like myelin figures and dense lysosome-like granules (Figs 2, 3, 4). However, the mitochondria and the endoplasmic reticulum apparently remain intact, and the nuclei present a less condensed chromatin than the nuclei of normal cells. These cells are separated from the subjacent ones by membranes parallel to the epithelial surface (Fig. 2).The exact moment of the cellular elimination was not captured in the preparations, but cellular debris were observed in the lumen . The autophagic vacuoles present in the dying epithelial cells of the termite midgut are very similar to the apoptotic bodies (MJ Arends, AH Wyllie 1991, Int Rev Exp Pathol 32: 223-254) and they have already been described for the mature state of epithelial cells in other termites (AM CostaLeonardo 1995 Naturalia, in press). The failure of the digestive cells may be regarded as a natural process of programmed cell death that may be under the influence of external conditions which probably accelerate the process, like the almost certain possibility of cell damage caused by food ingested by the insect. In insects the generative cells do not divide, but in the studied neuter caste of termites some cell division was observed. However, this occurrence can not be considered an exception since the neuter caste in Isoptera is constituted by immature forms and not by adults. In termites the only adults are the alates, the reproductive forms.

Vallate, foliate and fungiform human papillae gustatory cells. An immunocytochemical and ultrastructural study.

Abstract: We studied the classifications, topographic distribution and cellular lines of taste bud components in vallate, foliate and fungiform papillae of young, mature and old men with light microscopy, SEM, and TEM. By identifying ultrastructural and immunocytochemical characteristics, three distinct sensorial cells were identified, along with a few basal cells: dark type I cells, light type II cells and light type III cells. These cells extend from the epithelial basal lamina to the gustatory canal, where their apical cytoplasm sends long microvillous expansions. Excluding those of the fungiform papillae-which never go beyond the lower third of the gustatory canal, and are always void of dense substance-the microvillous expansions continue to the external border of the taste pore. Dark type I cells are rich in free ribosomes, tubular RER and large dense granules. Light type II cells with scarce ribosomes and RER, do not have enough peculiar ultrastructural characteristics to be considered effector or phagocyte elements. Light type III cells are characterizes by dense core vesicles whose peculiar ultrastructural characteristics in the foliate and vallate papillae, should be considered a consequence of different functional phases. After comparative evaluation the authors hypothesized on the functional value of some ultrastructural aspects and on the dense core vesicles which are immunoreactive to 5-HT. They observed that all gustatory cells are involved in taste transduction based on behaviours caused by microvilli in the gustatory canal and gustatory cell relationships with nerve endings. Moreover the authors noted that age does not seem to influence taste perception.

Ultrastructural and cytochemical characterization of cultured dogfish shark rectal gland cells.

Abstract: The dogfish shark rectal gland (SRG) is histologically complex, containing connective, nerve, and smooth muscle tissue and at least three types of epithelial cells: secretory tubule, central duct, and endothelial. This cellular heterogeneity precludes studies of the intact SRG from distinguishing direct tubular effects of mediators that modulate chloride secretion from their indirect effects on nonepithelial cells such as neurons. Primary SRG cultures express high levels of secretagogue-stimulated chloride secretion, suggesting that SRG cells retain a significant level of cytodifferentiation in vitro. However, because nontubular cells could contaminate these cultures, the question of whether secretagogues activate chloride secretion through direct or indirect effects on tubular epithelial cells remains unresolved. To address this issue, detailed ultrastructural and cytochemical analyses of SRG cultures were carried out to assess the level of cellular heterogeneity and the degree of cytodifferentiation expressed by SRG cells in vitro. The results demonstrate that, after 15 days, primary SRG monolayer cultures are composed exclusively of tubular epithelial cells with no detectable contamination by central duct cells, fibroblasts, smooth muscle cells, endothelial cells, or neurons. Tubular epithelial cells express most of the structural features of native SRG cells, including numerous mitochondria, massive basolateral surface amplification, complex tight junctions, and an extensive tubulovesicular system in the apical cytoplasm. Cultured SRG cells also display a striking level of polarization of cytoplasmic organelles and plasma membrane secretagogue receptors. These results account for the exceptionally high rates of electrogenic chloride secretion by SRG tubular epithelial cells in vitro and confirm that the effects of secretagogues on transport activity reflect their direct interaction with tubular epithelial cells.

The Presence of Granular Excretory Ducts in the Rabbit Zygomatic Gland

Abstract: The proximal and interlobular ducts of rabbit zygomatic glands show a particular morphological feature consisting of numerous secretory granules localized in the apical cytoplasm of the cells. It is suggested that there is a similarity between these ducts and the granular ducts of submandibular glands in rodents.

Localization of kallikrein in salivary glands of the Japanese monkey, Macaca fuscata

Abstract: Although Kallikrein has previously been localized in the duct cells of salivary glands, the manner in which it enters the saliva remains unclear. We used both immunofluorescein and protein A-gold methods at the light microscopic level and the protein A-gold method at the electron microscopic level to determine the distribution of kallikrein antigenicity in monkey salivary glands. The specificity of anti-human urinarykallikrein to glandular kallikrein in the monkey submandibular gland was demonstrated by Western blotting. Light microscopic immunohistochemical staining was intense at the luminal rim of the striated duct cells, but was less intense in the excretory duct cells, and was faint in the intercalated duct cells, Among the major salivary glands, staining intensity paralleled the degree of development of the striated ducts, with the submandibular gland exhibiting the most intense staining, the parotid to a somewhat lesser degree, and the sublingual displaying only minor staining. In the apical cytoplasm of the submandibular striated duct cells, some small granules and vesicles and vacuoles were observed near the luminal plasma membrane. By ultrastructural immunohistochemical staining, kallikrein appeared to be localized in small secretory granules. Because some of the small granules seemed to be attached to the luminal membrane, we suggest that kallikrein is secreted by exocytosis from the duct cells.

Immunolocalization of EGF receptor (EGFr) in intestinal epithelium: recognition of apoptotic cells

Abstract: The EGF-like family of growth factors are known to be involved in the control of the intestinal epithelium. The intracellular events are mediated by the EGF receptor (EGFr), a transmembrane glycoprotein which is overexpressed in many malignancies and also in many radiosensitive cell types. The precise mode of action of the receptor in controlling proliferation and whether the factor is also involved in controlling apoptosis in this tissue is not clear. Using polyclonal antibodies raised against a cytoplasmic region of the receptor distant to the phosphorylation site and one raised against the peptide sequence DVVDADEYLIPQ, which is present in the cytoplasmic tail phosphorylation site of the EGFr, we have examined the immunostaining in normal and irradiated murine intestine. The former antibody labelled the basolateral membranes of the epithelial cells in the proliferative zones of both the small intestine and colon, in both control and irradiated tissue. The latter antibody however, strongly labelled the Goblet cells and the microvilli of the enterocyte apical membrane in control tissue. Following irradiation\ the apical labelling redistributed and was localized in the apical cytoplasm and in a paranuclear region. Furthermore, strong labelling was now seen in many of the apoptotic cells of the small intestinal epithelium. The greatly differing results with the two antibodies indicates that interpretation of such immunostaining must be viewed with caution and may relate to the availability of each particular epitope. These results also suggest that antibodies to DVVDADEYLIPQ may be a useful marker of apoptotic calls and could imply a correlation between high levels of epitope availability, the radiosensitive (frequently p53 expressing) cells of the crypt epithelium and the induction of apoptosis.

[The fine structure of the gustatory cells of the circumvallate, foliate and fungiform papillae in hibernating bats].

Abstract: The cells of vallate, foliate and fungiform papillae were studied in insectivore hibernating bats (Pipistrellus pipistrellus and Rhinolophus ferrumequinum) in the various epochs of the year in order to show cell types the seasonal changes. On the basis of the ultrastructural aspects and the relationships with nerve endings, besides the few basal cells, three types of sensorial cells can be identified: dark type I cells, light type II cells and light type III cells. All gustatory cells, long and narrow shaped, extend from the epithelial basal lamina to the gustatory canal, where they send long microvillous expansions of the apical cytoplasm. These expansions, except those of the fungiform papillae which never extend beyond the lower two thirds, usually reach the external opening of the taste pore, always completely void of dense substance. Dark type I cells are characterized by a developed RER and large granules. Light type III cells show peculiar dense core light vesicles, labelled protein A-gold particles immunoreactive to 5-HT. These cells only in the foliate and fungiform papillae also have bundles of microtubules whose function is still unknown. After comparative evaluation and discussion of topographical and ultrastructural aspects with those of other mammals and humans, the Authors states that bats are provided with a valid gustatory system and that all cell types are involved in taste transduction.

Structural and biochemical modifications in parotid gland induced by fasting.

Abstract: Structural, ultrastructural and biochemical modifications produced by fasting in the parotid gland of guinea pig, were studied. The highest storage of secretory granules was found in the apical cytoplasm after a 12 hour fasting period. The curve of soluble proteins showed that the highest storage of proteins in the parenchyma took place after a 10/12 hour fasting period. Amylase activity reached its highest point after a 10 hour fasting period. We suggest that granules stored in cellular cytoplasm after a 12 hour fasting period would have completed their maturation cycle.

Specific amplification of ileal symbiont intracellularis from several animal species with proliferative enteritis

Abstract: Proliferative enteritis (PE) is an enteric disease that occurs at weanling age in a variety of animals, including the pig, hamster and horse.4,6,18 There are a variety of clinical presentations, including subclinical disease, reduced weight gain, diarrhoea, and an acute hemorrhagic form. Lesions of PE also vary, but all cases present with hyperplasia of the ileal crypt epithelium and large numbers of small, curved intracellular bacteria within the apical cytoplasm of crypt enterocytes (Fig. 1 and 2). These bacteria can be demonstrated with silver staining18 Other lesions such as gross thickening of the mucosa, inflammation, necrosis, and hemorrhage are variable and may represent complications with concurrent infections, variable chronicity, or host factors.18 The intracellular bacterium of PE has been referred to as a Campylobacter-like organism because of its morphology. However, 16S rDNA sequencing of the organism purified from pig and hamster intestines has shown it to share approximately 90% homology with Desulfovibrio desulfuricans and it has been given the vernacular name Ileal Symbiont (IS) intracellularis.7,17 Transmission studies in hamsters and pigs have confirmed the role of IS intracellularis as the causative agent of PE13, 16, 19.