Showing papers on "Apical cytoplasm published in 1978"

Specialized cell types in the human fetal small intestine.

Abstract: In the present study we describe the time of appearance and morphological differentiation of specialized epithelial cells in human fetal small intestine (SB). Proximal and distal SB from 36 nonviable fetuses was studied by light and electron microscopy. During the 9- to 10-week period, villi lined by simple columnar epithelium replaced the stratified epithelial lining which was two to six cell layers thick. During this transition, distinctive junctional complexes and a single secondary lumen were identified in the deeper layers of stratified epithelium, and there was evidence of cellular degeneration of some superficial cells. Oligomucous and mature goblet cells were present in both the stratified and simple columnar epithelium. Crypt formation began proximally at 10 to 11 weeks and, within a week, crypts lined by undifferentiated crypt cells (UCC) could also be identified in the distal SB. These cells resembled adult UCC's except for the presence of large aggregates of glycogen, and the absence of large adult-type secretory granules (SG) until 16 weeks. At all ages SG's were smaller and less numerous than in adults. Paneth cells appeared with crypt development at 11 to 12 weeks. Unlike adult Paneth cells their SG's were structurally heterogeneous and frequently had cores with halos of differing density. Caveolated or tuft cells with dense bundles of microfila-ments extending from microvilli into apical cytoplasm, apical granules, occasional caveolae, and a microvillus membrane denser than that of adjacent cells were identified by 16 weeks. Putative microfold (“M”) cells were seen in the distal SB of a 17-week fetus. These cells had an unusual apical border with irregular projections, many small membrane bound vesicles in the cytoplasm, and were in direct contact with underlying lymphoid cells. The glandular cells of Brunner's glands at 14 to 15 weeks resembled those of normal adult.

Comparative toxicity of polychlorinated biphenyl and polybrominated biphenylin the rat thyroid gland: light and electron microscopic alterations after subacute dietary exposure.

Abstract: The comparative toxicity of polychlorinated biphenyl (PCB) and polybrominated biphenyl (PBB) in thyroid glands was studied in male Holtzman rats. Four-week-old animals were fed at dietary levels of 0, 5, 50, and 500 ppm for 5 weeks and then sacrificed. PCB and PBB produced similar dose-dependent ultrastructural lesions in thyroid follicular cells of rats. The daily administration of 5 ppm of either PCB or PBB resulted in the accumulation of large membrane-limited colloid droplets and electron-dense lysosomal bodies within the cytoplasm of follicular cells. Microvilli were short and abnormally branched, and unique cytoplasmic processes extended from the apical surface of follicular cells into the luminal colloid. Similar but more severe ultrastructural changes were observed in thyroid glands of rats administered 50 and 500 ppm of either PCB or PBB. Many follicular cells were distended with large abnormal lysosomal bodies and colloid droplets. Mitochondria were often vacuolated with disrupted cristae. Microvilli were blunt with abnormal branching or absent from areas of the luminal surface of follicular cells. Processes of apical cytoplasm often extended into the follicular lumen in areas devoid of microvilli. Follicular cells remained responsive after the feeding of either PCB or PBB and underwent moderate compensatory hypertrophy and hyperplasia. Thyroid follicles were smaller than in controls and were lined by more columnar cells that occasionally formed papillary projections into the follicular lumens. PCB and PBB produced similar ultrastructural lesions in thyroid follicular cells which appeared to interfere with the synthesis and secretion of thyroxine.

Transmissible ileal hyperplasia of hamsters. II. Ultrastructure.

Abstract: The ultrastructure of developing ileal lesions was characterized in weanling hamsters with experimentally induced transmissible ileal hyperplasia (TIH). The primary lesion was mucosal hyperplasia with progressive replacement of mature villus columnar absorptive cells by undifferentiated crypt-type cells. The undifferentiated, mitotically active cells expanded onto villus walls from their normal location in crypts by Day 10 and reached villus tips by Day 14. Aggregates of slightly curved, 0.3 X 1.5 mu, rod-shaped bacteria were detected in the apical cytoplasm of crypt epithelium by Day ;. They replicated intracellularly and accumulated in progressively greater numbers in hyperplastic cells. Active penetration of cells by intralumenal bacteria was not seen. The appearance and distribution of TIH-associated antigen, demonstrated by indirect immunofluorescence, was identical to that observed for intracellular bacteria. Hyperplastic, bacteria-laden crypt epithelium penetrated adjacent supporting tissues. Dilated crypts with flattened epithelium ruptured and released organisms into surrounding tissues. Pyogranulomatous inflammation began at 17 to 25 days and preceded or accompanied penetration of the muscle layers by expanding crypts. Macrophages and neutrophils in inflammatory lesions contained many phagocytized bacteria. In some advanced lesions mature, bacteria-free absorptive cells and goblet cells reappeared. These observations support the hypothesis that intestinal bacteria cause TIH.

Ultrastructural evidence concerning the mode of secretion of electron-dense granules by Clara cells.

Abstract: An ultrastructural study of the secretory activity of non-ciliated bronchiolar epithelial (Clara) cells has been made. Membrane-bound, electron-dense granules were observed in the apical cytoplasm of Clara cells, immediately beneath the terminal web, and within terminal web regions, with their limiting membranes in close association with the plasma membrane of the cell. Granules were also observed in cytoplasmic pockets with varying amounts of their surfaces exposed to the bronchiolar, lumen, or within cytoplasmic projections into the lumen. Granules that were enveloped in a thin, uniform coat of cytoplasm and granules with no associated cytoplasm were both found free in the bronchiolar lumen. The study is consistent with the conclusion that the granules are secretory in nature, being extruded by a merocrine and possibly an apocrine mechanism.

Morphological and functional differentiation of the surface epithelium of the bursa Fabricii in chicken.

Abstract: Morphological and functional differentiation of the mucosal surface epithelium of the bursa Fabricii was studied in White Leghorn chicken fetuses and newly hatched chickens. First signs of differentiation towards two types of epithelial cells appeared on the thirteenth day of incubation: The apical cells of the epithelial buds projected towards the lumen, and an increase in the number of Golgi regions was observed in the epithelial cells between the buds. On day 15 the follicle-associated epithelium contained small apically situated vacuoles, and large mucin granules appeared in the interfollicular surface epithelium. Towards the day of hatching both epithelial cell types were arranged to a monolayered or pseudostratified cylindrical epithelium. The follicle-associated epithelium had invaginations and small vacuoles in the apical cytoplasm, whereas the interfollicular surface epithelium had numerous microvilli on its apical surface and large mucin granules in the apical cytoplasm. In functional studies, endocytosis of colloidal carbon was demonstrated in four out of ten 19-day fetuses and in all chickens studied immediately after hatching.

Histology and ultrastructure of the pig parotid gland

Abstract: Parotid glands of adult pigs were studied by light and electron microscopy. The parenchyma consists of acini, intercalated ducts, striated ducts, and excretory ducts. Acini had little affinity for periodic acid-Schiff and were alcian blue-negative at pH 2.6 or 0.5. These results indicate a paucity of neutral mucins and an absence of sialo- and sulfomucins. Histologically, acinar cells had vacuoles which corresponded ultrastructurally to large electron-lucent secretory granules. The latter contained electron-dense bodies and lipid droplets. Acinar cells differed histochemically and ultrastructurally from typical serous cells and were classified as special serous. Intercalated duct cells near acini contained electron-dense secretory granules and numerous microfilaments. Cells in distal segments lacked secretory granules. Striated ducts were lined by two types of columnar epithelial cells, light cells and dark cells. Light cells were characterized by numerous infoldings of the basal plasma membrane, mitochondria between the infoldings, and electron-lucent vesicles in the apical cytoplasm. The mitochondria contained tubular cristae. Dark cells were characterized by an abundance of microfilaments and numerous infranuclear processes which extended to the basement membrane. Excretory ducts, in addition to light and dark cells, also contained basal cells and goblet cells. Mitochondria in the light cells had flattened rather than tubular cristae. The pig parotid is a unique salivary gland and the most atypical mammalian parotid gland studied thus far. Mitochondria with tubular cristae and vacuolated special serous cells with lipid in the secretory granules are hallmarks of the pig parotid.

Characterization and localization of secretory component in the chicken.

Abstract: A component found free in intestinal contents and caecal contents of conventional and germ-free chickens (lacking IgA producing cells) was found to have similar characteristics to mammalian secretory component (SC). Free secretory component (FSC) showed a classic reaction of partial identity with secretory IgA (SIgA) from bile, intestinal contents and cystic oviduct fluid. Furthermore, there was demonstrable cross-reactivity between FSC and a low molecular weight component released from SIgA by mild reductive dissociation, confirming the presence of a disulphide-linked accessory polypeptide chain. Fractionation of serum IgA revealed two molecular classes of IgA, a high molecular weight 15S IgA which possessed SC and could not be differentiated antigenically from SIgA and a low molecular weight 7S IgA which showed a reaction of partial identity with 15S IgA and non-identity with FSC. Fluorescent localization of SC in young germ-free chicks demonstrated its presence in the supranuclear golgi zone, apical cytoplasm and basement membrane of crypt epithelial cells. It is concluded that the characteristics of chicken SIgA are closely aligned with those of its mammalian counterpart and are consistent with a system in which SIgA is the wynthetic product of two distinct cells, final assembly occurring in the crypt epithelium.

Ultrastructural cytochemistry of iron absorption.

Abstract: Conventional ultrastructural autoradiographic and morphologic studies of the duodenal mucosal cell have generally corroborated physiologic observations of iron absorption, but such methods have limited resolution and fail to distinguish ferric and ferrous iron. This study describes the application of the Prussian blue reaction as an electron microscopic cytochemical stain to the investigation of inorganic iron absorption in iron-deficient, normal, and iron-loaded rats. Ferrous iron is converted to ferric iron at the microvillus membrane. Subsequently intraepithelial ferric iron appears bound to a non-heme acceptor substance in microvilli and later appears as small non-membrane-bound stain deposits which are concentrated in the apical cytoplasm. The appearance of larger stain deposits in the lateral intercellular spaces, in the basal extracellular spaces, and along the intraluminal and extraluminal outer plasmalemma of adjacent endothelial cells of the lamina propria suggests passage of iron from epithelial cells through the lamina propria to blood vessels. The extreme sensitivity of the method compared with simultaneous ultrastructural autoradiographic techniques is demonstrated and suggests usefulness of the method in further studies of iron metabolism.

Studies on intestinal absorption of pivampicillin and species difference in the intestinal esterase activity

Abstract: The intestinal absorption and the site for hydrolysis of pivampicillin were compared with those of ampicillin by in situ ligated loop method in rats, using the radioactive compounds labeled at the phenylglycyl and the oxymethylene moieties. It was shown that pivampicillin is well absorbed from all parts of intestine, while ampicillin is absorbed from a more limited part of intestine. Pivampicillin was found to be rapidly transferred from the lumen into the intestinal wall as an intact ester and was hydrolyzed rapidly in the tissue. Ampicillin thus formed appeared to be transitorily accumulated in the tissue before being transferred into the portal venous blood gradually. Ampicillin was absorbed slowly without any accumulation in the intestinal wall. Microautoradiography of pivampicillin-14C in the intestine demonstrated that the radioactivity is accumulated in the epithelial cells in a high concentration. Histochemical and cytochemical detection of non-specific esterase revealed that a high activity is located specifically in the epithelial cells of villi and that the activity is localized in the membranes of endoplasmic reticulum as well as the cytoplasm, while there was almost no activity in the microvilli and terminal web region. It is considered therefore that pivampicillin is penetrated into the epithelial cells without any cleavage of the ester group and hydrolyzed by non-specific esterase in the apical cytoplasm of the cells. When the esterase activity was compared histochemically in rats, dogs and monkeys, it was found that the activity was extremely weak in dog intestine, providing an explanation for the fact that intact pivampicillin was detected in the portal venous blood only in dogs after oral administration. A possible relation between these results and the fact that a hepatic toxicity of pivampicillin was observed only in dogs among these animals was pointed out and discussed.

Cytological effects of hormones and plasma on bovine mammary tissue in vitro.

Abstract: Mammary explants from two heifers pretreated with oestradiol and progesterone were cultured for 96 h with various combinations of hormones and calf plasma to identify the complement causing mammary tissue development in vitro in the cow. Initial tissue histology, determined by quantitative morphological analysis, was maintained by incubation with insulin, cortisol, oestrogen and progesterone; enlarged lumina were observed after treatment with insulin and cortisol. Lactogenesis was induced in vitro by insulin, cortisol and prolactin, enhanced by adding oestrogen and progesterone at the doses used here and further stimulated by the addition of plasma. The most highly developed mammary alveoli were characterized by an increased luminal area with lipid and stainable secretion, epithelia with large lipid droplets in the apical cytoplasm and a limited stromal area. In a second experiment, samples of plasma were collected from two cows, successfully induced to lactate, on days 6, 15, 17, 19 and 21 after treatment with oestradiol and progesterone. Mammary gland explants from five heifers pretreated with oestradiol and progesterone in vivo were cultured with insulin and cortisol plus these plasma samples (30%, v/v) to test for changes in lactogenic activity. All plasma samples were found equally beneficial in promoting tissue differentiation. These experiments show that low concentrations of ovarian steroids synergize with prolactin at the level of the mammary epitherlium and suggest that other plasma components aid the development of bovine mammary epithelium in vitro.

Transmission Electron Microscope Observation of Epithelial Cells with Single Cilia in Intrahepatic Biliary Ductules of Bats

Abstract: Cells with long single cilia arising from basal bodies in the apical cytoplasm were occasionally revealed in the bile ductular epithelia of bats (Miniopterus schreibersi (Kuhl), Myotis macroductylus (Temminck) and Rhinolophus cornutus (Temminck)). The basal body (distal centriole) was associated with a proximal centriole, so the basal structure was of “two centriole type.” In cross sections of the long tapering cilia the arrangement of ciliary microtubules was determined. In the most proximal portion of the cilia doublet microtubules were arranged in the 9+0 pattern, while in more distal portions alteration and diminution of the doublet fibers occurred, splitting entirely into single microtubuli which were most frequently rearranged in the 6+1 or 7+1 pattern. The occurrence of the 9+0 fiber pattern and the basal structure of “two centriole type” suggested that the biliary ductular cilia might be sensory or chemoreceptive in nature and not motile. Similar cilia are expected to be found distributed widely in the epithelia of the excretory ductal system of large exocrine glands of vertebrate species.

Effect of autonomic agents on the amount of androgen-dependent granules in convoluted tubular cells of the mouse submandibular gland.

Abstract: The convoluted tubular cells of the male mouse submandibular gland contain many serous-like granules in their apical cytoplasm. The autonomic regulation of the secretory process of the contents of these granules was studied by the following two methods: (1) immunochemical method using an antiserum specific to the granular components; and (2) histometric observations using light and electron microscopes. The results obtained by these two methods were well in agreement. When male mice were administered either phenylephrine or norepinephrine, the amount of granules in the glands significantly decreased. These two adrenergic stimulators were very effective, whereas synephrine was less effective. When mice were injected with a beta-adrenergic agent(isoproterenol) or a parasympathomimetic agent (pilocarpine), the amount of granules in the glands did not change. The alpha-adrenergic blockers phenoxybenzamine and phentolamine almost completely neutralized the effect of alpha-adrenergic agents on the glands, whereas another alpha-blocker (ergotamine) was less effective. These facts suggest that the secretion of the granular components is mediated by way of alpha-adrenergic receptor sites in the glands.

Postnatal development and differentiation of the opossum submandibular gland.

Abstract: The postnatal development and differentiation of the submandibular salivary gland has been examined in sixteen groups of young opossums. At birth the glandular elements, dispersed in loose connective tissue, consist only of ducts that are immature in appearance and of irregular secretory end-pieces. Development occurs in two phases, the first from birth to approximately 31 days postnatum, and the second thereafter. During the first phase the ductular elements show separation into intercalated and intralobular ducts, and attain structural maturity. The larger ducts are concentrated centrally within each lobule and lie in a markedly vascular connective tissue. The secretory end-pieces, initially acinar in form, are lined by proacinar cells which exhibit intercellular canaliculi at the lateral cell membranes and a few dense granules in the apical cytoplasm. During the second phase of development extensive changes occur within the secretory end-pieces, which elongate to form a system of branching tubules. Component cells show an increased granular content, and those in the main body of the tubules differentiate into mucous cells. By 34 cm postnatum the proacinar cells in the bulbous endings of the tubules are replaced by special serous cells possessing intercellular canaliculi and secretory granules which are either electron-lucent or electron-dense. The sequence of changes that occur during postnatal development is discussed and related to possible functional activities. The early development of the ducts may be correlated with their role in homeostasis, while the later development of secretory tubules and the differentiation of secretory cell types may be related to the onset of weaning, and may possibly be induced by this major change in dietary habit.

魚類嗅上皮の比較形態学的研究-ii ニシン目

Abstract: The olfactory rosettes of five species of Clupeiformes were studied by scanning and transmission electron microscopy. They are all oval in shape, consisting of 24-30 unfolded lamellae. Each lamella is composed of centrally located sensory epithelium encircled by marginal indifferent epi-thelium. In Etrumeus teres and Engraulis japonica, the sensory epithelium contains three types of cells, i. e., cells projecting 3-5 relatively long cilia radially from a round cell apex (type 2 ciliated cells), cells bearing a tuft of long microvilli (microvillous cells) and supporting cells provided with short microvilli. In Harengula zunasi, Sardinops melanosticta and Konosirus punctatus, cells bearing many cilia in a tuft (type 1 ciliated cells) are sparsely scattered in the sensory epithelium in addition to the above three cell types. Apical cytoplasm of supporting cells in Etrumeus is filled with large electron-lucent droplets.

Stereological analysis of the duct system of the rabbit parotid gland.

Abstract: The duct system of the rabbit parotid gland constitutes about 5% of gland tissue volume and is divisible into intercalated and striated ducts in a volumetric ratio of about 3:2. The intercalated duct consists of low cuboidal epithelial cells (375 micrometer 2) surrounded by a myoepithlium, and the cells contain a few small secretion granules, particularly at the proximal end of the duct. The cells of the striated duct are larger (531 micrometer 3), columnal in shape, and show a mitochondrial compartment three times that of intercalated duct cells (16.5% of cell volume). These mitochondria are concentrated in a basal and perinuclear position, but they are largely absent from the apical cytoplasm, which is permeated with microfilaments and contains numerous small smooth membraned vesicles, but no clearly recognisable secretion granules. The lateral plasmalemma of these cells is complexly folded, and basal processes interdigitate with those of adjacent cells. This results in an increase in the ratio of apical to lateral/basal plasmalemma from 1:5 in intercalated cells to 1:24 in striated cells. Some slight changes in cell morphology were detected following isoprenaline-induced secretion of the gland in vivo. These included a small increase in the volume fraction of nuclei and mitochondria in intercalated duct cells, and depletion of their secretion granules. Change in striated cells was confirmed to a small increase in the volume of smooth membraned cytoplasmic vesicles. The structure of the duct and changes wrought by isoprenaline are discussed in the context of the role of the duct in the production of saliva.

Ultrastructural changes of the early visceral yolk sac layer of mouse embryos after maternal injection of trypan blue.

Abstract: The ultrastructural features of the early visceral yolk sac epithelium of normal mouse embryos on day 9 were compared to those whose mothers had received a single subcutaneous injection of 100 mg/kg trypan blue on day 8. The following results were obtained: In normal embryos the visceral yolk sac cells are predominantly characterized by numerous membrane bounded inclusions localized in the supranuclear cytoplasm. In embryos of animals treated with trypan blue, at about 12h after injection large single and only partly membrane bounded vacuoles are observed occupying most of the apical cytoplasm. Up to 24h after injection large cytoplasmic areas are seen which are in a stage of autodigestion possibly due to leakage of the vacuolar content. These alterations are exclusively limited to the visceral yolk sac epithelium whereas in the cells of the embryonic part, e.g. head process, no changes could be found. The observations are discussed in relation to the mechanism of the teratogenic activity of trypan blue.

Immunohistochemical localization of thyroid hormone in rat thyroid gland.

Abstract: Direct and indirect immunofluorescence techniques were used to localize the thyroid hormones triidothyronine (T3) and thyroxine (T4) in adult rat thyroid gland. Optimum dilutions of the antisera were established and four tissue fixatives were investigated for usefulness in this technique. Use of antibodies specific for either T3 or T4 resulted in brilliant fluorescence in the colloid pools and apical cytoplasm of follicular cells. In all cases, the adjacent parathyroid gland was devoid of fluorescence. This report demonstrates that these dipeptide hormones can be localized by using immunofluorescence techniques.

Scanning electron microscopic studies of ileal epithelial cells in suckling rats.

Abstract: The ileal epithelial cells containing the tubulo-vacuolar systems and supranuclear vacuoles in suckling rats were investigated with scanning electron microscopy, using specimens treated with osmium-thiocarbohydrazide-osmium staining methods, and critical point drying and cracking. The cracked surface of the apical cytoplasm is seen as irregular and small hollows and pores of the anastomosing and branching tubulo-vacuolar system. The cracked surface of the supranuclear vacuoles shows the ellipsoidal structures. Numerous pores of various size and irregular shape are present on the apical inner surface of the supranuclear vacuole. These pores are clearly the openings from the tubulo-vacuolar system to the supranuclear vacuole. Some small pores are visible on the inner lateral surface of the supranuclear vacuole, especially near the nucleus. They are probably the pathways of the absorbed materials from the supranuclear vacuole into the lateral cytoplasm. Usually, the inclusions of the supranuclear vacuole reveal the globes or coarse and sponge-like networks.

Cytochemical localization of complex carbohydrates in the thyroid gland of normal and TSH-treated mice.

Abstract: The silver methenamine method for the ultrastructural localization of carbohydrates and glycoproteins was applied to the thyroid glands of normal and TSH-treated mice. The majority of the cisternae of the rough endoplasmic reticulum showed a weak, but apparently positive reaction. These findings support the opinion that glycosylation of thyroglobulin occurs initially in the rough endoplasmic reticulum. By this method the Golgi apparatus was observed to display a staining gradient. The intermediate to inner saccules were intensely stained, whereas the outer saccules were not so heavily stained. This phenomenon indicates that the Golgi apparatus has a functional polarity for the addition of carbohydrates to thyroglobulin and other proteins. In the inner and/or the peripheral regions of the Golgi apparatus and in the apical cytoplasm, a large number of globules of various sizes, considered to be colloid droplets, lysosomes and apical secreting vesicles, showed a positive reaction. The luminal colloid was also positive with silver methenamine staining, with almost the same intensity as the globules and vesicles.

Light and electron microscopic study of rat lung brush alveolocytes

Abstract: The 52 alveolar brush cells (ABC) were revealed in the semi-thin sections of the rat lung tissue, metachromatically stained with toluidine blue. Characteristic features of the ABC on the light microscope level were the following: pyramidal body shape, basal position of the nucleus, darker stain tinge of the cytoplasm than that of other alveolar cells, the presence of microvilli on the small free cell surface. There is one ABC per 21 alveocytes, type 2, and 15 alveocytes, type 1. 41.1% of the ABC are localized in places of adjacent alveolus walls junction, 32.7%--on the alveolus wall facing the alveolus cavity, 16.8%--near the alveolus entrance; 9.4% of the cells are directed into the cavities of two neughbo ring alveoli or settle down near the pores of Kohn. In parallel electron microscopy there was revealed in ABC a form of granular cytoplasmic reticulum (unusual for other alveolocytes) in the form of blocks made up of 5-8 cysternae as if adherent one to another, bundles of filaments and microtubules, vacuoles in the apical cytoplasm. The ultrastructure of ABC, their topography, and incidence in the alveoli of rats evidenced their chemoreceptor nature.

Some observations on ciliogenesis in the oviduct epithelium of the mouse.

Abstract: Ciliogenesis in the epithelium of the oviduct ampulla of 5-9 day-old mice has been investigated by electron microscopy. As reported by many investigators, fibrous granules, deuterosomes, and procentrioles are important for ciliogenesis. After injection of colchicine, fibrous granules disappear, while numerous coated vesicles and lysosome-like dense bodies appear in the same region, and the formation of deuterosomes and procentrioles is impeded. In the ciliogenic cell, the Golgi apparatus, consisting of numerous vesicles, is very well developed, and a large number of microtubules are distributed between the supranuclear and apical cytoplasm. In addition to these, many small vesicles, some of which are fused with the plasma membrane, occur in the apical cytoplasm. These vesicles, which may be derived from the Golgi apparatus, are considered to be necessary for the apical plasma membrane, because the protrusion of cilia requires additional plasma-membrane substance during their differentiation and development. The microtubules, some of which are connected with these vesicles, might play some role in the movement of these vesicles from the Golgi field to the apical cytoplasm. When colchicine is administered to suckling mice, formation of microtubules is blocked in the upper part of the ciliated cell, and the apical vesicles disappear. This also indicates that the microtubules bring the vesicles from the Golgi field to the apical region of the cell.

Present status of the zinc glycinate marker (ZGM).

Abstract: ZGM was purified from both primary and metastatic colonic carcinomas demonstrably positive for ZGM by immunofluorescence microscopy. ZGM purification included preparative Pevikon electrophoresis, Sepharose 4B molecular exclusion chromatography and Con A-Sepharose affinity chromatography. ZGM had an alpha2 electrophoretic mobility, an estimated molecular weight by Sepharose 4B equal to or greater than 2 x 10(6), and did not bind to Con A-Sepharose, although having determinants with CEA-like activity. Its immunologic activity was resistant to trypsin or phospholipase A but not to neuraminidase. Antisera prepared to ZGM and absorbed with saliva, when tested by double immunodiffusion, formed a single precipitation line with saline extracts of colon tumors and did not cross-react with CEA, AFP, normal tissue extracts, ferritin, NCA, NCA-2, CSAp, blood groups A, B, H, Lewis antigen, or buffy coat, alpha-2 macroglobulin, saliva or ovarian cyst fluid. Immunofluorescence microscopy confirmed the presence of ZGM in 40 out of 45 adenocarcinomas of the GI tract staining primarily in tumors, the apical cytoplasm, and in grossly nonmalignant tissues, the deep crypts of the villi, while all of 22 non-GI tumors in the study were ZGM negative.

Morphology of the retinal pigment epithelium in the vitamin A deficient rat

Abstract: Ultrastructural changes in the retinal pigment epithelium (RPE) and adjacent photoreceptor cells have been followed in the Wistar rat during the course of long-term vitamin A deficiency. Of particular interest has been the discovery of unusual concentric aggregates within the photoreceptor outer segments and the inner cytoplasm of the RPE. The aggregates were present throughout the course of the retinal degeneration induced by vitamin A deficiency and could be identified in the RPE either by themselves in the apical cytoplasm or within phagolysosomes. It is postulated that the concentric aggregates result initially from abnormal formation or condensation of outer segment membranes and are then slowly degraded by lysosomal action in the RPE cytoplasm. In addition, acid phosphatase activity and typical phagosomes (shed outer segment packets) have been demonstrated in the cytoplasm of the RPE of the vitamin A deficient rats. The latter findings indicate that, at least to some extent, the normal phagocytic and lytic processes of the RPE are retained in this nutritional disorder.

Ultrastructure of thyroid follicular cells following hypophysial portal vascular infusion of thyrotropin‐releasing hormone

Abstract: Ultrastructural changes in thyroid follicular cell morphology were studied following the infusion of thyrotropin-releasing hormone (TRH) for 1 min into a hypophysial stalk portal vessel of adult male rats. At 1, 5, 15 and 30 min following infusion, thyroid glands were removed and prepared for electron microscopic examination. Thyroid follicular cells in unoperated, sham-operated non-infused, and saline-infused control rats were cuboidal, generally lacked intracellular colloid droplets and contained variable numbers of electron-dense lysosome-like bodies distributed throughout the cytoplasm. In experimental animals, marked intracellular colloid droplet accumulation was observed 5 min after TRH infusion and remained a constant finding throughout the time-periods studied. Numerous lysosome-like dense bodies accumulated in the apical cytoplasm of thyroid follicular cells at 30 min. Fusion of colloid droplets and lysosome-like bodies had apparently occurred by 30 min. At this time the colloid droplets were smaller, more electron-dense and were often located more basally within the follicular cell cytoplasm. This study suggests that the morphological response of thyroid follicular cells to hypophysial portal vascular infusion of TRH occurs rapidly and mimics, both temporally and morphologically, the response observed following systemic administration of exogenous TSH.

Light-optical and electron-microscopic study of alveolar brush cells of the rat lung

Abstract: In semithin sections through rat lung tissue stained metachromatically with toluidine blue 52 alveolar brush cells (ABC) were discovered. During a light-optical study the distinguishing features of these cells were the pyramidal shape of their body, the basal position of the nucleus, the darker staining of the cytoplasm than in other alveolar cells, and the presence of microvilli on the small free surface of the cell. For every 21 type II and 15 type I alveolar cells there was one ABC. Of the total number of ABC 41.1% are located at junctions between neighboring alveolar cells, 32.7% on the alveolar wall facting the cavity of one alveolus, 16.8% near the entrance to the alveoli, and 9.4% facing the lumen of two adjacent alveoli simultaneously or near Cohn's pores. Parallel electron-microscopic investigations revealed a granular cytoplasmic reticulum in ABC of an unusual type for other alveolar cells; it consisted of blocks of 5 to 8 apparently confluent tubules, bundles of fibers microtubules, and vacuoles in the apical cytoplasm. The structural organization of the ABC, their topography, and the frequency with which they were found in the alveoli of rats are evidence that these cells are chemoreceptor in nature.

Fine morphology of the secretory mode of the tetragastrin-stimulated chief cells of human and dog gastric mucosa

Abstract: The chief cells of the gastrin-stimulated gastric mucosa of human and dog were observed under a light and electron microscope. Four μg/kg AOC-tetragastrin were given parenterally by a single shot to a man and three dogs respectively. Pepsinogen in the gastric mucosa increased at the wash-out stage and at the following dynamic equibrium stage of the chief cell secretion cycle after the administration of AOC-tetragastrin. During those stages, the chief cells released zymogen granules intensively. As the main ultrastructural process for releasing the zymogen granules, the emiocytosis in man and the apical cytoplasm dissociation in dog were discussed.