Showing papers on "Apical cytoplasm published in 1985"

Maturation and polarization of the endocytotic system in outside blastomeres during mouse preimplantation development

Abstract: The maturation and distribution of the endocytotic apparatus in outside cells of cleavage-stage mouse embryos have been studied to determine the nature and sequence of changes associated with the differentiation of the polarized trophectoderm epithelium of the blastocyst. Various quantitative and qualitative techniques used at the light and electron microscopic levels have revealed an incremental pattern of endocytotic maturation and polarization. Oocytes, eggs and blastomeres within embryos up to the early 8-cell stage contain clusters of prelysosomal endocytotic vesicles (endosomes) distributed randomly in the cortical cytoplasm. During the 8-cell stage and continuing into the early 16-cell stage, endosomes become progressively localized in the apical cytoplasm beneath the microvillous pole. Endosome polarization is initiated prior to overt polarization of the surface membrane. Concomitant with endosome polarization, pinocytotic activity at the cell surface, revealed by horseradish peroxidase labelling, becomes segregated preferentially to the apical rather than the basolateral membrane. The final maturation phase occurs at the late 16-cell stage when secondary lysosomes, characterized by trimetaphosphatase reactivity, form and polarize in the basal cytoplasm.

Ultrastructural localization of Tamm-Horsfall glycoprotein (THP) in rat kidney as revealed by protein A-gold immunocytochemistry

Abstract: The present study describes the intracellular distribution of Tamm-Horsfall protein (THP) in rat kidney. The localization was determined by immunoelectron microscopy using the protein A-gold technique. Various fixation and embedding protocols were evaluated for this purpose. Brief perfusion fixation (3 min) with 1% glutaraldehyde and embedding in a highly hydrophilic glycol methacrylate-polyester mixture were most appropriate for antigen-antibody recognition and structural preservation. The overall tissue distribution of THP was evaluated by indirect immunofluorescence microscopy; reaction was strong along the entire thick ascending limb of the loop of Henle (TAL) with enhanced fluorescence in the apical cytoplasm. On the electron microscopic level immunogold labelling was concentrated over numerous membrane-bound vesicles which form a compartment in the apical cytoplasm. The Golgi region was consistently labelled, whereas the plasma membranes revealed only sporadic labelling at the luminal side, and basolateral membranes were mostly unlabelled. Quantitative evaluation of the gold labelling, which was separately done for the inner stripe, outer stripe and cortical TAL, consistently showed the highest particle density in the apical cytoplasm. Middle and basal levels in the TAL cells were only moderately labelled. The results are discussed with respect to the current opinion which describes THP as a membrane glycoprotein. We speculate that the accumulation of THP in the apical vesicular compartment of TAL cells indicates a storage site of the protein, possibly prior to extrusion via exocytosis of the vesicle contents.

Target cells for the polychlorinated biphenyl metabolite 4,4'-bis(methylsulfonyl)-2,2',5,5'-tetrachlorobiphenyl. Characterization of high affinity binding in rat and mouse lung cytosol.

Abstract: When a tritium-labeled metabolite of polychlorinated biphenyls (PCB), 4,4'-bis[( 3H]methylsulfonyl)-2,2',5,5'-tetrachlorobiphenyl [(3H-MeSO2)2TCB] is administered intraperitoneally to rats, a selective labeling is registered in the apical cytoplasm of the nonciliated bronchiolar (Clara) cells of the lung as determined by microautoradiography of sections of methacrylate-embedded tissue. In vitro, (3H-MeSO2)2TCB binds with high affinity (Kd = 2.5-15 nM) and high capacity (Bmax = 30-70 pmol/mg of protein) to rat lung cytosol. Binding of (3H-MeSO2)2TCB to the high affinity sites is temperature dependent, reversible, and saturable. The sites seem to reside within a protein-like component, since proteolytic enzymes significantly reduce the binding. Physiochemical characterization of the (3H-MeSO2)2TCB-binding protein indicates a Stokes radius of 22 A and a sedimentation coefficient of 1.7 S and, on the basis of these parameters, an apparent molecular weight of 16,000 may be calculated. The binding entity has an apparent pI of 5.3 and elutes as a single radioactive peak from CM-Sepharose at 75 mM acetate. Binding with similar affinities (IC50 values, 4-65 nM) is shown to occur also with other PCB methyl sulfones, whereas only one PCB, 2,2',4,4'5,5'-hexachlorobiphenyl, competes for (3H-MeSO2)2TCB binding, but with a lower affinity (IC50 = 3 microM). Among other compounds tested, only progesterone and some derivatives thereof display an affinity for the (3H-MeSO2)2TCB-binding protein (IC50 values ranging from 1 to 10 microM). Lung cytosol shows by far the highest amount of specific (3H-MeSO2)2TCB binding. However, low but detectable amounts are also found in cytosolic preparations from prostate, kidney, and large intestine. Finally, (3H-MeSO2)2TCB also binds to an entity in mouse lung cytosol with the same physicochemical characteristics as that in rat lung cytosol and to a progesterone-binding protein purified from rabbit uterus (uteroglobin). It is concluded that rat lung contains a uteroglobin-like macromolecule with a pronounced affinity for at least certain PCB methyl sulfones, and it is suggested that this binding entity is responsible for the striking accumulation of such metabolites in lung tissue following administration of PCB to rats and mice.

Morphology of the bovine epididymis.

Abstract: The epididymis of the bull was divided into six regions, and morphological differences between regions were studied. The epithelium of all regions contained four cell types: principal and basal epithelial cells, and intraepithelial lymphocytes and macrophages. The epithelium of regions II-V also contained a few apical cells. Principal cells of all regions possessed an endocytotic apparatus including stereocilia underlain by canaliculi, coated vesicles, and subapical vacuoles (up to 1 micron in diameter); however, large vacuoles with a flocculent content and multivesicular bodies (up to 5 microns in diameter) were most numerous in regions II, III, and IV. The unique features of principal cells of region I were the presence of well-developed Golgi bodies, few lipid droplets, and whorls of smooth endoplasmic reticulum in the supranuclear cytoplasm. Numerous mitochondria, distended cisternae of rough endoplasmic reticulum, and dense granules characterized the infranuclear cytoplasm of the principal cells of regions II-VI; however, these features were more developed in region V. Apical cells were characterized by the apical location of the nucleus, many mitochondria in the apical cytoplasm, and few microvilli at the luminal border. Basal cells with few cytoplasmic lipid droplets were present throughout the length of the epididymis but appeared more numerous in region V. Intraepithelial lymphocytes were present at all levels of the epithelium but were never seen in the lumen. Intraepithelial macrophages containing heterogeneous granules, eccentric nuclei, and pseudopods were invariably seen near the basal area of the epithelium in all regions. These observations are discussed in an effort to define the role of each cell type in the epididymal epithelium.

Structure of taste buds in foliate papillae of the rhesus monkey, Macaca mulatta.

Abstract: Taste buds in foliate papillae of the rhesus monkey were examined by electron microscopy. Three distinct cell types were identified. Type I cells were narrow elongated cells containing an oval nucleus, bundles of intermediate filaments, several Golgi bodies, and characteristic apical membrane-bounded dense granules. These cells exhibited morphological variations: some had a moderately dense cytoplasm, perinuclear free ribosomes, and flattened sacs of rough endoplasmic reticulum; others had a more lucent cytoplasm, dilated irregular rough endoplasmic reticulum, lysosome-like dense bodies, and lipid droplets. Type II cells typically contained a spherical, pale nucleus, a prominent nucleolus, supranuclear and infranuclear Golgi bodies, mitochondria with tubular cristae, and one or two centrioles. This cell type, too, showed some variation in the relative amounts of ribosomes and smooth endoplasmic reticulum, which varied inversely with each other. Type III cells were characterized by a clear apical cytoplasm essentially devoid of ribosomes and containing microtubules. In a few type III cells, the peri- and infranuclear regions contained many ribosomes and some rough endoplasmic reticulum. In most Type III cells, there were large numbers of dense and clear vesicles in the peri- and infranuclear regions; some of the vesicles were grouped in synapse-like arrangements with adjacent nerves. The morphological variations exhibited by all three cell types could be accounted for by age differences in each of the cells. This would be consistent with the notion that cell renewal occurs in each of the three cell populations.

Alpha and beta types of carbonic anhydrase-rich cells in turtle bladder.

Abstract: The carbonic anhydrase-rich (CA) cell population of the turtle urinary bladder, which is responsible for the secretion of H+ and probably of HCO-3, was studied by freeze-fracture and thin-section electron microscopy. The apical membrane of the major CA cell type (alpha type) was characterized by microplicae and by a coat of studs on its cytoplasmic side; on freeze-fracture, it contained a dense population of rod-shaped intra-membrane particles. When fixed at low CO2 tension, the apical membrane area of the alpha cell was reduced; its surface displayed microplicae as well as microvilli, and the apical cytoplasm contained many vesicles with rod-shaped particles and studs. The apical membrane of the other (beta type) CA cell was characterized by numerous individual microvilli without microplicae and by a relative absence of rod-shaped particles and studs. Instead, the beta cell contained studs and rod-shaped particles in its basolateral membrane. The ultrastructure and frequency of the beta CA cell were not affected by changes in CO2 tension. We suggest that the alpha cell is responsible for H+ secretion. The reversal of the polarity of the membrane elements in the beta cell and failure to respond to CO2 with amplification of its apical membrane are consistent with a role in HCO-3 secretion.

Target cells for the polychlorinated biphenyl metabolite 4,4'-bis(methylsulfonyl)-2,2',5,5'-tetrachlorobiphenyl in lung and kidney.

Abstract: Light microscope autoradiography was used to determine the cellular localization of the polychlorinated biphenyl metabolite 4,4'-bis([14C] methylsulfonyl)-2,2',5-5'-tetrachlorobiphenyl ([3H]TCB) in the lung and kidney of mice and rats Microautoradiograms prepared from thaw-mounted freeze sections showed that the radioactivity in the lung was localized in the bronchiolar lumen and epithelium In methacrylate sections (74-82% of radioactivity extracted), a highly selective labeling was registered in the apical cytoplasm of the Clara cells A pronounced labeling was present also in certain goblet-like cells containing periodic acid-Schiff-positive granules Gel permeation chromatography and density gradient centrifugation showed that 80-95% of the radioactivity in lung lavage fluid was bound to a specific protein previously characterized in rat and mouse lung cytosol The protein appeared to be enriched in the lavage fluid, as compared to lung cytosol These data suggest that [3H]TCB binds to a protein residing in the Clara and goblet-like cells and that the labeled TCB-protein complex is subsequently secreted into the airway lumen As shown by microautoradiography, the radioactivity in the kidney was confined to a restricted portion of the nephron, predominantly to the apical region of the proximal tubular cells

Intracellular transport of horseradish peroxidase in the absorptive cells of goldfish hindgut in vitro, with special reference to the cytoplasmic tubules

Abstract: This study was undertaken to determine whether the numerous cytoplasmic tubules (CT) in the apical cytoplasm of goldfish hindgut absorptive cells are directly involved in the endocytotic transport of macromolecules into the cells, or whether they are derived from the intracellular membrane components. The absorptive cells were exposed to horseradish peroxidase (HRP)-containing medium in organ culture and subsequently fixed and prepared for electron microscopy. Analysis revealed that 5 sec after exposure, many vesicular structures, including coated vesicles, were labelled with reaction product whereas almost all CT were negative. After a 1-min exposure, reaction product was detected in about 11 % of the CT, and thereafter, the percentage increased to about 95% after 15 min exposure. As labelled CT increased in number, the number of densely labelled vacuoles with attached CT also increased. CT connected to vacuoles with a peripheral margin of dense reaction product were always HRP-positive, whereas those connected to vacuoles which were not distinctly labelled were themselves also devoid of HRP reaction product. This indicated that the labelling of CT was closely associated with the labelling of the inner surface of the vacuolar membrane. These results indicate that CT are probably formed by a budding off from these vacuoles, rather than being directly involved in endocytosis.

The trophotaenial placenta of a viviparous goodeid fish. I. Ultrastructure of the internal ovarian epithelium, the maternal component.

Abstract: Embryos of goodeid fishes develop to term within the ovarian lumen, where they undergo considerable increase in weight due to transfer of maternal nutrients across a trophotaenial placenta. The placenta consists of an embryonic component, the trophotaeniae, and a maternal component, the ovarian lining. The latter was examined by transmission electron microscopy, scanning electron microscopy, and light microscopy in both gravid and non-gravid ovaries of the viviparous goodeid fish, Ameca splendens. The single median ovary of A. splendens is a hollow structure whose lumen is divided into lateral chambers by a highly folded longitudinal ovarian septum. Germinal tissue occurs within folds of the ovarian lining that extend into each of the two lateral chambers. Matrotrophic embryonic development takes place within ovarian chambers. During gestation, the lining of the ovarian lumen is in direct apposition to body surfaces and trophotaenial epithelia of developing embryos. The ovarian lining consists of a simple cuboidal epithelium, termed the internal ovarian epithelium (IOE), overlying a well-vascularized bed of connective tissue. Cells of the IOE are apically convex. Well-developed granular and agranular endoplasmic reticula and numerous large membrane-bound vesicles with electron-dense content occupy the apical cytoplasm of IOE cells. Two functional states of the same cell type are distinguished within the IOE. Phase I cells contain few, if any, large apically situated vesicles; Phase II cells contain many. Secretory products of the IOE are presumed to be an important source of nutrients for embryonic development. Structural and functional relationships of the IOE to the trophotaenial epithelium of developing embryos are discussed in relation to maternal-embryonic nutrient transfer processes.

Histochemical studies of Ca-ATPase, succinate and NAD+-dependent isocitrate dehydrogenases in the shell gland of laying Japanese quails: with special reference to calcium-transporting cells.

Abstract: In order to elucidate the problem of which cells are involved in calcium transport and to estimate the role of mitochondria in calcium transport in the avian shell gland, the fine structure and the Ca-ATPase, succinate dehydrogenase (SDH) and nicotinamide adenine dinucleotide (NAD+)-dependent isocitrate dehydrogenase (NAD+-ICDH) activity of the shell gland of egg-laying Japanese quails were examined. The surface epithelial cells, consisting of ciliated cells with cilia and microvilli and non-ciliated cells with microvilli, had many large and electron-dense granules. The tubular-gland cells occupied the proprial layer and lacked secretory granules. When an egg was in the shell gland, the well-developed mitochondria of tubular-gland cells characteristically tended to accumulate in the apical cytoplasm, while they were scattered throughout the cytoplasm when an egg was not in the shell gland. Intense Ca-ATPase activity was found on the microvilli of tubular-gland cells, and moderate activity was found on the lateral-cell surface. In the surface epithelial cells, the basolateral cell surface showed moderate enzymatic activity. Both SDH and NAD+-ICDH activity were found in tubular-gland cells when an egg was in the shell gland. These results strongly suggest that calcium for eggshell calcification is actively transported by the tubular-gland (depending on Ca-ATPase activity) and that the mitochondria of gland cells may play an important role in this process as an energy source.

Lectin-binding patterns in the developing tooth.

Abstract: The lectin-binding patterns of the cells involved in amelogenesis and dentinogenesis in developing teeth of rats were studied. Undifferentiated odontogenic epithelia exhibited very slight staining with almost all of the lectins examined. The lectin-staining affinities of secretory ameloblasts could be divided into two categories: Concanavalin-A (Con-A), Wheat germ agglutinin (WGA) and Soybean agglutinin (SBA) binding occurred from the middle to apical cytoplasm, whereas Ricinus communis agglutinin-I (RCA-I) and Ulex europeus I (UEA-I) binding predominated in the basal regions. The cells of the stratum intermedium exhibited relatively strange lectin staining, which appeared to be dependent on ameloblastic maturation. The basement membranes in undifferentiated epithelia were markedly positive for lectin binding. Odontoblasts showed moderate Con-A staining on the apical side of the cells, as well as slight-to-moderate reactions with WGA and SBA. Pulp cells and dental papillae showed slight-to-moderate lectin staining, and predentin and dentin were also moderately positive for Con-A and RCA-I binding and slightly so for WGA and SBA. The lectin-binding affinities were enhanced during the formation of enamel and dentin, and appeared to be dependent on the degree of cellular differentiation in ameloblasts and odontoblasts.

Distribution of dense core granules in normal, benign and malignant breast tissue

Abstract: In this study breast tissue from 114 patients has been examined ultrastructurally for dense core granules (DCG). The tissue included examples of normal 'resting', pregnant and lactating breast plus various benign and malignant lesions. DCG were observed in low numbers in the apical cytoplasm in a proportion of the examples of 'resting' and pregnant breast tissue but were absent in the lactating patients. The incidence appeared to relate to hormonal changes. They were present in 50 per cent of the benign lesions examined. DCG were also observed in a high proportion of the ductal, lobular and tubular carcinomas examined and were associated with luminal differentiation. In the mucoid carcinomas over half the tumours possessed some DCG with large numbers of DCG present within certain of the malignant cells in two cases. It is possible that the granules could be related to mucin secretion. Therefore, in normal, benign and malignant (with the exception of mucoid carcinoma) breast tissue the presence of DCG would appear to be related to hormonal changes and represent prelactational differentiation rather than providing evidence of neuroendocrine differentiation. We emphasize the need for a comprehensive knowledge of the normal morphological variations within a tissue before attempting to interpret its tumours.

Three-dimensional reconstruction of a small-granule paracrine cell cluster in an adult hamster bronchus.

Abstract: Amine precursor uptake and decarboxylation (APUD) small-granule cells were stained by periodic acid-Schiff (PAS)-lead hematoxylin in 0.5-micron etched Epon sections of adult hamster lung fixed for transmission electron microscopy. The leading edge of a small-granule cell cluster was identified in a segmental bronchus as a single PAS-positive cell. From 256 serial thin sections through its entirety, a three-dimensional wooden reconstruction of the cluster and morphometric estimates of the apical and basal surfaces, cell volume, and intracytoplasmic distribution of mitochondria and small granules was made. Of moderate size, the body consisted of 16 small-granule cells, 11 forming its ovoid core with five outlying cells diverging at the margin; these were pyramidal, possessing wide bases and thin apical processes. At the bronchial surface, processes from the 11-cell core emerged together, whereas the divergent cells emerged in groups of two and three. Ten Clara-like cells and one ciliated cell encircled the core. Altogether they formed a pseudostratified epithelium in contrast to the surrounding simple columnar epithelium. Deeper in the cluster, numerous cytoplasmic extensions interdigitated with those from adjacent cells, and toward the base the Clara-like and APUD cells were increasingly interposed. In marked contrast to the apical cytoplasm, the infranuclear cytoplasm of the latter was densely packed with ca. 1,000 A electron-dense granules; and the basal, presumptively secretory face of each cell was five to six times greater than the area exposed to the bronchial lumen. Judged by granule size and ultrastructure, only one APUD cell type was recognized in the reconstructed cluster. Beneath it many fibrocytic processes were separated from the APUD cells by only the thickness of the basal lamina. Two fascicles of smooth muscle approached the cluster within 0.4-0.8 micron. Unmyelinated nerve fibers came as close but contacted only the muscle. Capillaries, in contrast, came no closer than 15 micron from the base of the body. Evidently, 1) fibrocytes and smooth muscle are more likely targets for secretions from such a paracrine body than cells reached through the blood-stream, and 2) not all small-granule cell clusters are innervated.

Morphological and physiological studies of rat kidney cortex slices undergoing isosmotic swelling and its reversal: A possible mechanism for ouabain-resistant control of cell volume

Abstract: Slices of rat kidney cortex were induced to swell by preincubation at 1°C in an isotonic Ringer's solution, and their capacity to reverse swelling, by net extrusion of cellular water, was studied during subsequent incubation at 25°C. The recovery from swelling was prevented by the respiratory inhibitor, antimycin A. On the other hand, extrusion of water was little affected by ouabain. The extrusion of water continuing in the presence of ouabain (but not that in its absence) was significantly reduced when furosemide was added or when medium Cl− was replaced by NO 3 − , or I−. There was substantial variability in the morphological appearance of cells within the cortical slices. Different segments of the nephron showed different structural changes during swelling and its reversal, the proximal tubules being most markedly affected. Proximal tubular cells of swollen slices showed disorganization of brush borders and expansion of their apical surfaces, and contained vesicles in their apical cytoplasm. Upon recovery at 25°C, the apical portions of these cells showed reversal of the expansion, but some apical vesicles remained. These vesicles were much more numerous after recovery in the presence of ouabain, but they were much reduced in numbers, or totally absent, when recovery took place in the presence of furosemide or absence of Cl−, with or without ouabain. The vesicles seen in the presence of ouabain alone appeared to fuse with each other and with infoldings of the basolateral plasma membrane. Rather similar results were obtained with distal tubular cells in the slices. We suggest that volume regulation in the proximal and distal tubular cells proceeds by way of two mechanisms. The first consists of extrusion of water coupled to the ouabain-sensitive transport of Na+ and K+. The other proceeds by way of an ouabain-resistant entry of water into apical cytoplasmic vesicles, following furosemide-sensitive movements of Cl− and Na+; the vesicles then expel their contents by exocytosis at the basolateral cell borders.

Ultrastructural changes in the retinal pigment epithelium of congenitally blind chickens.

Abstract: Pathological changes in the retinal pigment epithelium (RPE) in a strain of chickens having hereditary blindness and retinal degeneration were described at the ultrastructural level. Photoreceptors in the retinal degenerate (rd) chicken had previously been noted to degenerate within a week after hatching. Affected chicks have neural retinas that are morphologically comparable to normal animals prior to that time despite an obvious lack of vision. In the present study, no pathological changes were noted in rd RPE prior to the time of photoreceptor degeneration. However, while mitochondria in the normal chick's RPE underwent diurnal changes in morphology within a few days of hatching, pleomorphic or ring mitochondria were not seen with high frequency in the rd chick. After photoreceptors began degenerating, changes were seen in the rd RPE. By 2 weeks of age, we noted a reduction in the depth and number of basal infoldings, an increase in number and size of autophagic vacuoles and large whorls of membranous material within rd RPE cells. Membranous debris and what appeared to be broken off outer segments were seen in the subretinal space at that time. These phenomena became more prominent and prevalent with time. In 3-4 week old specimens, nearly intact outer segments were seen within RPE cytoplasm. At the same time very few intact outer segments were present on photoreceptors. After this time degenerative changes were seen in the RPE: a thinning of cells (apical to basal cell width), spreading out of cells (increased distance between intercellular junctional complexes), hypopigmentation of cells and presence of free cells in the sub-retinal space. Some RPE cells appeared in a rounded up configuration, bulging into the subretinal space and making junctional complexes with remaining photoreceptor inner segments or Mueller cell processes. Many RPE cells did appear to maintain their phagocytic abilities, as evidenced by presence of many microvilli and pinocytotic vacuoles in the apical cytoplasm.

Transport of horseradish peroxidase across monkey trophoblastic epithelium in coated and uncoated vesicles.

Abstract: This study used membranous chorion of the macaque monkey placenta to examine uptake and processing of exogenous proteins. Tissue was incubated with either cationic or anionic horseradish peroxidase. Incubation time was varied between 5-25 min to follow the endocytic pathways. In spite of some differences in binding, uptake and processing of the isozymes was similar. In the presence of tracers at 37 degrees C both horseradish peroxidases were taken up in large (150-175) nm diameter) coated vesicles. In addition, coated tubules 300-400 nm in length and 50-100 nm in diameter were seen in the apical cytoplasm. Studies using ruthenium red indicated that the coated tubules were derived from long coated invaginations of the free surface that pinch off into the apical cytoplasm. Often, the tubules bud off small (85-105 nm diameter) protein-filled coated vesicles which traversed the cytoplasm and fused with the basal-lateral plasma membrane. In other cases, the tubules or vesicles lost their clathrin coats and fused to form larger endocytic vesicles which later fused with phagolysosomes. After long incubation, larger uncoated vesicles (endosomes) were seen releasing their contents at the basal-lateral membrane. These results suggest that multiple transport pathways exist in this epithelium. The first, involving only coated structures, may function to sort and concentrate specific ligands important for embryonic development. The second, involving the formation and translocation of large uncoated vesicles to the basal-lateral membrane, may also provide nutrients to the embryo. A third pathway directs the protein to phagolysosomes where it is presumably degraded.(ABSTRACT TRUNCATED AT 250 WORDS)

Electron microscopical findings with special reference to cancer in rats caused by inhalation of nickel oxide.

Abstract: A special exposure system was used for the inhalation of nickel oxide (NiO) aerosol by Wistar male rats. The median aerodynamic diameter and the geometric standard deviation were 1.2 μm and 2.2, respectively. A histopathological study of the rats was performed immediately, and at intervals of 12 and 20 mo after a 1-mo expsoure to NiO. Electron microscopy showed that localization of NiO particles was restricted to the lungs and that each particle had been engulfed by the alveolar macrophages. Type II pneumocytes and nonciliated bronchiolar epithelial cells (Clara cells), as well as numerous tubular myelin (surfactant) in the alveoli were prominent. In rats dissected after 12 mo, clusters of NiO particles were still present within the terminal bronchioli, alveolar walls, and lysosomes of the alveolar macrophages. Pools of tubular myelin were observed in the peribron-chial lymphatics. The Clara cells, which project into the lumen of bronchioli, showed active secretion and were filled with smooth en-doplasmic reticulum (SER) in the apical cytoplasm. In the experimental group sacrificed after 20 mo, one rat had papillary adenocarcinoma and two rats showed adenomatosis in the peripheral portion of the lung, but none in the upper respiratory tract.

Effects of colchicine on the ultrastructure of mouse taste buds.

Abstract: Effect of colchicine on the ultrastructure of taste bud cells was studied in the mouse. In untreated mice microtubules were abundant throughout the entire cytoplasm of type-III cells, but only in the apical cytoplasm of type-I cells. After 2 h of colchicine treatment, no microtubules were observed in any taste bud cells; dense secretory granules in the apical cytoplasm of type-I cells mostly disappeared, and instead, numerous phagosomes appeared. It is suggested that colchicine causes an interruption of the transport of the secretory granules in type-I cells from the Golgi apparatus to the membrane of the apical surface, from which release occurs. In type-III cells, after 4 or 5 h of treatment, dense-cored vesicles scattered throughout the cytoplasm tended to increase in number; they were often observed to accumulate in the vicinity of the Golgi apparatus. Five hours after treatment with 5-hydroxy-L-tryptophan (5-HTP) following colchicine pretreatment, monoamine specific fluorescent cells and vesicles with highly electron-dense cores of type-III cells were still present. On the other hand, 5 h after 5-HTP treatment alone both fluorescent cells and vesicles with highly electron-dense cores had already disappeared. These observations suggest that the treatment with colchicine interrupts the transport of dense-cored vesicles of type-III cells to synaptic areas, in which those vesicles are presumed to discharge the neurotransmitter substance.

Morphometric analysis of coated pits and vesicles in the proximal and distal caput epididymidis.

Abstract: A morphometric analysis of coated and uncoated structures found in the apical portion of principal cells from both the proximal and distal caput epididymidis has been carried out. Almost all endocytic, coated vesicles are found within 1 micron of the luminal surface of principal cells and the volume fraction of these and of uncoated vesicles is much greater in the proximal caput epididymidis. A serial section analysis indicated that many coated "vesicles" are tangentially sectioned coated pits and that a complex network of interconnected vesicular and tubular structures exists in the apical cytoplasm. Efferent duct ligation has no effect on the number of size of large coated and uncoated vesicles in either the proximal or distal caput epididymidis, indicating that substances delivered to principal cells from the lumen are not required to maintain the endocytic machinery. However, this treatment does result in a considerable increase in the number of large coated vesicles associated with the basal surface of principal cells from the proximal but not the distal caput epididymidis. The volume fraction of small, presumably exocytic, coated vesicles is significantly greater in the apical cytoplasm of cells from the distal caput epididymidis in control animals. Efferent duct ligation results in a significant increase in the volume fraction of these vesicles in the proximal but not distal caput epididymidis. These results show that there are marked differences in structure among principal cells from these two regions of the epididymis and that this may reflect differences in control and function.

Ultrastructural and immunohistochemical studies on non-ciliated cells of the tracheal epithelium of normal, phenobarbital-treated and 3-methylcholanthrene-treated mice.

Abstract: Non-ciliated SER-rich cells of the tracheal epithelium of normal, phenobarbital-treated and 3-methylcholanthrene-treated mice were studied ultrastructurally and immunohistochemically The apical portion of these cells protrudes into the tracheal lumen, especially in the mice treated with the two compounds, and the apical cytoplasm is filled with numerous tubular elements of SER Besides, the non-ciliated cells of 3-methylcholanthrene-treated mice show a strong positive reaction to the antiserum against microsomal cytochrome P-450 of liver These findings support the concept that the non-ciliated tracheal cell may be involved in the metabolism of endogeneous and exogeneous chemical compounds

The allantois of the North American opossum (Didelphis virginiana) with preliminary observations on the yolk sac endoderm and trophectoderm.

Abstract: During the middle of prenatal day 10, the opossum allantois forms as a ventral outgrowth of the hindgut. By day 11 it appears as a large, fluid filled sac and by the middle of day 12 (just prior to birth) it reaches its maximal development. The simple squamous epithelium lining the allantois consists of only one cell type that often contains numerous filaments in the apical cytoplasm. At the luminal surface, the apices of the cells are united by junctional complexes and desmosomes are present between adjacent cells. The luminal surface is irregular, whereas laterally and basally the cell membranes show few if any infoldings. Mitotic figures and presumptive degenerating cells occasionally occur in the allantoic epithelium which rests on a delicate basal lamina. The allantois is covered by a simple squamous mesothelium that lacks a distinct basal lamina. Between the two epithelial sheets lie mesenchymal cells, collagen fibers, and blood vessels. No specializations of cell membranes were noted in either of the epithelial layers. The yolk sac endoderm consists of a single layer of squamous cells whose cytoplasm contains scattered profiles of rough endoplasmic reticulum and mitochondria. Extensive lateral and basal infoldings of the plasmalemma were not observed in these endodermal cells. The morphology of the trophectodermal (trophoblastic) cells indicates a cell type that is active in the transport of materials. Since the endodermal cells that line the allantois lack morphological features that would suggest the presence of mechanisms for transport or exchange, and because they remain relatively unchanged throughout pregnancy, it is thought that the allantois functions primarily in the storage of urinary wastes during prenatal life.(ABSTRACT TRUNCATED AT 250 WORDS)

Use of autolytic enzyme for isolation of protoplasts from Fusarium tricinctum Hyphae

Abstract: Fusarium tricinctum was grown in shake culture at 25 °C for a 15 day incubation period. The appearance and accumulation of lytic enzymes in the culture fluid were investigated as the culture aged and autolysed. Changes in the activity of chitinase, β-glucanase, α-glucanase, protease, acid and alkaline phosphatase, invertase and esterase were monitored. Although limited autolysis occurred during incubation of F. tricinctum (25 %) and no chitinase activity was detected, culture filtrates containing maximum β-glucanase activity (obtained after 6 days incubation) were effective in liberating protoplasts from young mycelium of the same species. It is suggested that protoplasts liberated by this method were isolated from apical regions of mycelium and the use of autolysis enzyme therefore represents a method for the preferential isolation of apical cytoplasm. Culture filtrate samples from ageing cultures of F. tricinctum also liberated protoplasts from F. oxysporum strains.

Morphogenesis of the subcommissural organ in the hamster.

Abstract: Morphogenesis and cytodifferentiation of the subcommissural organ (SCO) of the hamster were studied by light, and scanning and transmission electron microscopy, from 11.0 to 15.6 days of gestation and to 60 days after birth. The cells of SCO were differentiated at 12.5 days of gestation, earlier than the adjacent ordinary ependymal cells. The SCO consisted of tall columnar epithelial cells with less developed organelles and short cilia. At 13.0 to 14.5 days of gestation, many polysomes and a small number of rER and microtubules were observed in the cytoplasm. At 15.0 days, rER, sER and microtubules were increased in number. Just before birth (15.5-15.6 days of gestation), cisternae of rER became slightly swollen and filled with flocculent substances. At 0 to 2 days after birth, the cisternae of rER were enlarged remarkably, and moderately electron-dense granules appeared in the apical cytoplasm. Irregular thread-like fibrils, apparently secretory materials, began to cover a part of the ventricular surface of the SCO, together with conspicuously stretched cilia. At 2 to 3 days after birth, secretory materials in the cytoplasm and in the ventricular surface became to be stained positively by chrome-alum hematoxylin, with the first appearance of Reissner's fiber. At 5 to 20 days, rER became more conspicuously swollen and filled with flocculent substances, as was observed in the adult.

Problems in the differential diagnosis of Kartagener's syndrome and ATP-ase deficiency.

Abstract: Summary Two cases of Kartagener's syndrome with a partial loss of the dynein arms and the central spokes within the cilia are presented. In light microscopic examination the predominant cell types were mast cells within the stroma and the epithelium and plasma cells and lymphocytes in the stroma. The reaction for the magnesium-activated ATP-ase located in the apical cytoplasm of ciliated cells was negative in one case and slightly positive in the same case on year later; in our second case, the ATP-ase reaction was variable, slightly to moderately positive, in the same biopsy. Besides the dynein arm defect this is a second defect of another ATP-ase, located in the apical region of the ciliated and mucus producing epithelial cells. Based on histological examination of nasal mucosal biopsies a differential diagnosis has been established for Kartagener's syndrome, the more common cystic fibrosis and the relative frequent allergic rhinitis.