摘要:

AbstractThe three‐dimensional structure of alveolar epithelial type II cells was imaged using a computer‐based system designed for reconstruction and quantitative analysis of serially sectioned specimens. Six type II cells were reconstructed from serial ultrathin sections of lungs from two Sprague Dawley male rats and the results were compared to standard morphometric estimates of type II cell compoition from five other Sprague Dawley male rats. A minor portion of the type II cell surface was in contact with the alveolar airspace while most of the cell surface was embedded in the alveolar septal interstitium. The type II cells contained multiple Golgi regions located close to the nucleus. Mitochondria formed a few branching filamentous networks extending throughout the cell. The reconstructed cells appeared to represent a homogeneous population having fractional volumes of intracellular organelles very similar to those found by morphometric techniques. The spatial distribution of secretory organelle volume suggests that the organization of this cell type reflects an ordered progression of secretory particle maturation which is consistent with earlier hypotheses of lamellar body assem

ISSN:0002-9106    

DOI:10.1002/aja.1001740102

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1985

数据来源: WILEY

摘要:

AbstractThe precise anatomical relation by which autonomic nerve endings contact gastric epithelial cells to enhance the rate of gastric secretions is not fully understood. The aim of the present study was to clarify this issue by using the technique of serial section reconstruction of areas of the gastric mucosa. The work also explored the possibility of a functional role for a system of smooth muscle strands in the gastric mucosa that emanate from the muscularis mucosa, run in the lamina propria, and are associated in a unique manner with the gastric glands. Electron microscopic serial sections of the gastric mucosa were performed to visualize the entire limiting membrane of gastric epithelial cells to determine any nerve associations (especially varicose endings) with these cells. Evaluation of serial sections of five separate parietal cells showed that their basal membrane did not come in close contact (nearest distance 500 nm) with any nerve axon or varicosity. Moreover, the axons passing in the area of these cells ultimately showed varicose endings associated with smooth muscle cells in the adjacent connective tissue (often separated by only 20 nm), with mast cells or with vascular elements. Additionally, the lateral membrane of these five parietal cells did not contact any endocrine cell in the epithelium, although other parietal cells in the area were adjacent to endocrine cells. Chief cells in the immediate area also did not form any close associations with nerve varicosities. Random analysis of 5,000 additional epithelial cells in these sections showed no close associations to nerve elements with significant accumulations of neurosecretory vesicles (varicosities). Because of the observed existence of innervation to the smooth muscle strands in the area of the gastric glands, serial 1‐μm epoxy sections of the gastric mucosa were prepared, and profiles of smooth muscle and gastric glands were entered into a computer‐assisted reconstruction system. Three‐dimensional reconstruction techniques were employed to reveal the existence of a unique association between the mucosal smooth muscle strands and the gastric glands. The muscle strands arose from the muscularis mucosa at regular intervals and became branched to form an intricate wrap around a series of gastric glands that empty into one gastric pit. Branching of the muscle strands initially occurred at the point where they approached the base of the glands and then emanated into the connective tissue around the glands in a crossing pattern, ending at the base of the gastric pit. Although muscarinic agents have been shown to directly stimulate parietal cells to secrete acid, these findings have led us to postulate that autonomic nerve stimulation may also aid gastric secretion both by stimulation of mast cells and by glandular excretion mediated via mucosal muscular contra

ISSN:0002-9106    

DOI:10.1002/aja.1001740103

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1985

数据来源: WILEY

摘要:

AbstractMice were injected three times a day for 12 days with 300 μg/kg body weight of gastrin G17 or 37.5 Ivy dog U/kg body weight of CCK or saline. Other mice were also injected four times an hr for 1 hr with 7.5 μ/kg of gastrin, nine Ivy dog U/kg of CCK or saline; 1 hr before killing, they were injected with tritiated thymidine to evaluate the labelling indices in peptic, antral, duodenal, jejunal, and ileal mucosae. Four hours after the first injection of the two peptides, the peptic labelling indices increased while those of intestinal mucosa increased 8 hr after these injections. Long‐term injections of CCK had a trophic effect on secretory cells of the digestive tract: the number of gastric zymogenic cells, Paneth cells, and the mucous cells of Brünner glands were hypertrophied. The pepsin, amylase, chymotrypsin, and lysozyme activities increased in stomach, exocrine pancreas, and intestine, respectively. Neither parietal cells nor intestinal enterocytes and hydrolase activities were affected. The trophic effect of long‐term injections of gastrin is confirmed on parietal cells and exocrine pancreatic parenchyma and is demonstrated in Paneth cells. Confirming cytological results, pancreatic lipase and amylase activities and intestinal lysozyme activity were increased after gastrin. Although CCK and gastrin have a structural analogy, these two peptides did not affect the same cellular types. A specific action of CCK on the main secretory cells of the digestive mucosa is demons

ISSN:0002-9106    

DOI:10.1002/aja.1001740104

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1985

数据来源: WILEY

摘要:

AbstractThe avian salt gland provides an ideal system for the study of plasma membrane (PM) biogenesis. Feeding ducklings 1% sodium chloride (salt stress) induces the secretory cells of the gland to synthesize large amounts of PM, which forms an extensive basolateral PM domain after 7–9 days of treatment. In the present study, the initial biosynthetic events following salt stress were investigated.In vivostudies using3H‐uridine indicated that increased rates of RNA synthesis could be detected by 2 hr after the beginning of salt stress and continued through at least 12 hr. Underin vitroconditions, increased rates of protein and glycoprotein synthesis (as monitored by3H‐leucine and3H‐fucose incorporation, respectively) were also detected after 2 hr and continued through 7–9 days. Increased levels of Na, K‐ATPase, a specific secretory cell PM marker, were detected after 8 hr of treatment as monitored by specific activity and3H‐ouabain binding. Sodium dodecyl sulfate‐polyacryl‐amide slab gel electrophoresis coupled with fluorography indicated that both3H‐leucine and3H‐fucose were incorporated into partially purified preparations of Na, K‐ATPase isolated after 12 hr. Light microscopic autoradiographic analysis of pulse‐chase experiments indicated that in secretory cells of 12‐hr salt‐stressed glands,3H‐leucine‐ and3H‐fucose‐labelled products reached the cell periphery by 1–2 hr after the initial pulse. The incorporation of both tritiated precursors was predominately associated with the secretory cells. Quantitative electron microscopic autoradiography indicated that3H‐leucine is initially taken up by elements of the rough endoplasmic reticulum (RER) and cytoplasm (5 min postpulse), subsequently transported to and concentrated within components of the Golgi apparatus (10 min of chase), and ultimately incorporated into all domains of the plasma membrane of secretory cells by 1–2 hr of chase. The data is consistent with a flow of newly synthesized membrane components from RER to Golgi to plasma membrane and is analogous to the pattern previously found for the synthesis and processing of

ISSN:0002-9106    

DOI:10.1002/aja.1001740105

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1985

数据来源: WILEY

摘要:

AbstractGlycoconjugates were localized by light microscopy with lectin‐peroxidase conjugates and by electron microscopy with the periodic acid‐thiocarbohydrazide‐silver proteinate (PA‐TCH‐SP) sequence in immunocyto‐chemically or morphologically identified cell types in rat pituitary. Lectin histochemistry demonstrated sialic acid and glycoconjugates with N‐glycosidically linked oligosaccharides in gonadotrophs, thyrotrophs, and corticotrophs. Galactose penultimate to sialic acid was observed mostly in gonadotrophs. The terminal galactose‐N‐acetylgalactosamine disaccharide was detected in a few gonadotrophs and in a moderate number of mammotrophs. Fucose was localized in only corticotrophs with two fucose‐binding lectins and in thyrotrophs with another. Several different monosaccharides were seen in glycoconjugates in melanotrophs and in Herring bodies. Melanotrophs displayed heterogeneous staining with fucose‐binding lectins. A small number of nonsecretory cells were also visualized in the pars distalis by virtue of their glycogen content. PA‐TCH‐SP staining revealed complex carbohydrates in secretory granules and some Golgi cisternae in all types of hormone‐producing cells in the pars distalis except for the somatotrophs. Melanotrophs of pars intermedia exhibited stained secretory granules and irregular dense bodies containing a stained meshwork. Corticotrophs of the pars distalis lacked the latter bodies, although they from the same glycoprotein precursor hormone as melanotrophs. Lectin conjugates and the PA‐TCH‐SP sequence stained some groups of secretion granules in Herring bodies, possibly representing vasopressin‐containing granules as well as oth

ISSN:0002-9106    

DOI:10.1002/aja.1001740106

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1985

数据来源: WILEY

摘要:

AbstractThe effects of the bisphosphonate HEBP on dentin formation and the structural relationship between the dentin and the developing periodontal attachment apparatus have been studied in the continuously growing mouse incisor. It was observed that HEBP (in doses ≥ 8 mg P/kg b.w/day) not only inhibited the deposition of mineral crystallites in newly formed dentin matrix, but also entirely prevented the formation of a layer of acellular root cementum. It was further noticed that the drug interfered with the deposition of3H‐serine‐containing substances at the predentin‐dentin border. This was not always accompanied by an inhibition of dentin mineralization, thereby suggesting that3H‐serine‐containing proteins (presumably phosphoproteins) do not play a critical role in the deposition of mineral layers onto previously formed ones. The absence of a cementum layer did not prevent the developing periodontal ligament from establishing matrix‐to‐matrix connections with the root‐analogue dentin. Collagen fibrils of the ligament intermingled with those of the mantle dentin, which in contrast to teeth not exposed to the drug were clearly visible and not masked by electron‐dense matrix components. Finally, it was found that the drug had distinct effects on the formation of root‐analogue and crown‐analogue dentin. Whereas during the course of the experiment the odontoblasts along the crown‐analogue aspect of the tooth continued to produce circumpulpal dentin matrix, those along the root‐analogue aspect of the tooth did so only when the mantle dentin layer had been mineralized prior to HEBP administration. This phenomenon is interpreted as being indicative of fundamental differences between the formati

ISSN:0002-9106    

DOI:10.1002/aja.1001740107

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1985

数据来源: WILEY

ISSN:0002-9106    

DOI:10.1002/aja.1001740101

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1985

数据来源: WILEY