摘要:

AbstractSprague‐Dawley strain rats of 4–5 weeks old were perfusion‐fixed with either a mixture containing 0.1 or 0.25% glutaraldehyde and 2% formaldehyde, or a 2% formaldehyde in 0.1 M sodium cacodylate buffer for 10 minutes. Non‐decalcified 30–50‐μm sections of the enamel organ taken from lower incisors were then processed for ultracytochemical demonstration of ouabain‐sensitive, K+‐dependent, p‐nitrophenyl phosphatase, by use of the one‐step lead method, representing the second dephosphorylative step of Na+‐K+‐ATPase. Throughout the secretory, transition, and maturation stages of amelogenesis, the enzymatic activity was demonstrated along the cytoplasmic side of the plasma membranes of the stratum intermedium and the papillary layer cells, especially along their numerous micro‐villi. The plasma membranes forming gap junctions and desmosomes were free of reaction or showed slight focal precipitates of reaction products. The stellate reticulum and the outer enamel epithelium exhibited either a weak reaction or were reaction negative. Secretory ameloblasts showed a weak trace‐like reaction along the basal and lateral cell surfaces; however, the latter surfaces were sometimes completely free of reaction. Tomes' processes were usually reaction negative. Ameloblasts in the transition and maturation stages were devoid of enzymatic activity, except for a slight reaction along the plasma membranes of the basal cell surfaces of transition ameloblasts facing the papillary layer. The enzymatic activity described above was completely dependent on the presence of potassium and substrate in the incubation media and was almost completely inhibited by an addition of 10 mM oua

ISSN:0003-276X    

DOI:10.1002/ar.1092160102

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

年代:1986

数据来源: WILEY

摘要:

AbstractThe distribution of exogenous horseradish peroxidase (HRP) in the secretory ameloblast layer of developing rat molar tooth germs was examined in a culture system with and without colchicine. The secretory ameloblast of cultured tooth germs engulfed HRP added to the medium regardless of the presence of colchicine. The reaction product was localized in various vesicles and granules. Without colchicine in the medium, many small vesicles containing HRP were located in the Tomes' processes, whereas only a few were present with colchicine at concentrations above 5 μM. An intense reaction of HRP also appeared in the distal extracellular spaces beyond the distal junctional complexes of ameloblasts cultured without colchicine, whereas it became almost indiscernible in the tooth germs cultured with colchicine. The lack of HRP in the Tomes' processes and distal extracellular spaces of ameloblasts treated with colchicine might be attributed to the disruption of microtubules. The present study suggests that the secretory ameloblast is able to transport tracer molecules through the intracellular pathway from the proximal and lateral extracellular spaces to the distal extracellular space

ISSN:0003-276X    

DOI:10.1002/ar.1092160103

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

年代:1986

数据来源: WILEY

摘要:

AbstractOsteodentin formation was studied in rat incisor pulp after adriamycin administration. Male Sprague Dawley rats (100 ± 5 gm) were injected intravenously with adriamycin (5 mg/kg body weight), and after 7 days they were again injected intravenously with3H‐proline (3 μCi/gm). These animals were killed in groups of three from 5 minutes to 4 hours after proline injection by perfusion with 3% phosphate‐buffered formaldehyde followed by 2.5% phosphate‐buffered glutaraldehyde. Control animals injected with only physiological saline, and 7 days later with3H‐proline (3 μCi/gm), and were killed at the same time intervals. Radioautography on sections showing osteodentin formation revealed that at 5 minutes after3H‐proline injection the labeling was located over the cells associated with the osteodentin matrix. At 1 hour after injection the labeling was located over the cells and the matrix, while at 4 hours the labeling was seen only over the matrix. It therefore appears that at least a proline‐containing component of the osteodentin matrix is synthesized and secreted by the cells asso

ISSN:0003-276X    

DOI:10.1002/ar.1092160104

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

年代:1986

数据来源: WILEY

摘要:

AbstractNeovascularization of the anterior stroma of the rat cornea was associated with prolonged zinc deficiency (in this model). There was also an increase in the myelinated nerves of the cornea. Blood vessels were not observed in the corneas of the pair‐fed and ad‐libitum‐fed control animals. The invading blood vessels were frequently associated with Schwann cells and neurites. Unmyelinated nerves were observed in the corneal stroma of all three experimental g

ISSN:0003-276X    

DOI:10.1002/ar.1092160105

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

年代:1986

数据来源: WILEY

摘要:

AbstractThe epithelium of the guinea pig yolk sac is involved in the selective transport of macromolecules to the fetus. We studied the compartments involved in sorting and transepithelial transport of protein tracers and the effect of lowered temperature (18°C) on these events. Explants of yolk sac were incubated with a mixture of cationized ferritin (CF) and horseradish peroxidase (HRP, Sigma type VI). At 4°C, both tracers were bound to the cell surface and binding of an HRP‐gold complex was shown to be inhibited by mannan. At 37°C and 18°C, both tracers were taken up into tubules and vesicles in the apical cytoplasm. Usually the tubules contained a mixure of tracers, but they often showed a polarized distribution with CF and HRP at opposite ends. The vesicles also contained mixtures of the tracers, but some contained only one. In addition, there were some irregularly shaped vacuoles composed of saccules that contained either a mixture, HRP alone, or CF alone. These results suggest that these adsorbed ligands are binding to unique microdomains of the endocytic complex. After 20 min at 37°C coated vesicles 100 nm in diameter were located in the apical cytoplasm and coated vesicles of the same size were located at the lateral cell membrane. Usually they contained only HRP or CF, although occasional mixtures were seen. At 18°C, HRP was transported across the cells in 100 nm vesicles. However, transport of CF was completely inhibited at the lower temperature. Although uptake at 18°C was slower than that at 37°C, experiments with125I‐CF allowed comparison of time points at which equal uptake had occurred. These experiments demonstrated that inhibition of CF transport was not due to decreased amounts of internalized CF. These differences in transport of HRP and CF suggest that multiple compartments are involved in the sorting and transepithelial transport of protein, and at least one is perturbed by lower

ISSN:0003-276X    

DOI:10.1002/ar.1092160106

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

年代:1986

数据来源: WILEY

摘要:

AbstractTextbooks in embryology, histology, and reproductive biology erroneously state that the mammalian rete ovarii consists of a tubular structure in the medulla of the ovary which is closed at both ends. In white‐tailed deer and cattle, the lumen of the rete ovarii opens directly into the infundibulum near its attachment to the ovary. This serendipitous discovery followed the serial sectioning of over 100 ovaries. Secretions through this tuboretial opening may affect reproductive processes. Obstructions could explain the development of cysts of clinical importance in both human and veterinary medicine. This rather obscure structure may have more significance than previously recognize

ISSN:0003-276X    

DOI:10.1002/ar.1092160107

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

年代:1986

数据来源: WILEY

摘要:

AbstractNew crypts are added continously to the adult mouse intestinal epithelium by a process of crypt replication. Branching crypts found in the epithelium represent a stage in the process of crypt replication. In “normal” human colonic epithelium we found a small but definite percentage of branching crypts, 0.44 ± 0.16, indicating that new crypts are being produced at a low rate in this epithelium. Significantly higher (P<.001) percentages of branching crypts, 30.4 ± 5.75, 15.1 ± 1.08, and 13.2 ± 1.05, were found in diseased colonic epithelium from patients with ulcerative colitis, Crohn's disease, and multiple polyposis, respectively. These results may be interpreted as suggesting that the rate of crypt production in human colonic epithelium is increased in a number of disease states. We concluded that, as in the mouse intestinal epithelium, the rate of the crypt replication process in human colonic epithelium is plastic and may respond to a variety of con

ISSN:0003-276X    

DOI:10.1002/ar.1092160108

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

年代:1986

数据来源: WILEY

摘要:

AbstractThe distribution of brush cells in the rat lung was studied using electron microscopic morphometry. Samples were taken from six distinctive anatomical regions. Tissue from the trachea, lobar bronchi, terminal bronchioles, first alveolar duct bifurcations, proximal alveolar regions, and the distal alveolar region were isolated and embedded in Epox 812. Aside from the trachea and the lobar bronchi, the other four regions were isolated from embedded tissue using microdis‐section techniques. Electron micrographs taken from thin sections of these samples were analyzed. It was found that brush cells made up 10% of the volume of epithelium covering the first alveolar duct bifurcation. Approximately 2% of the proximal alveolar epithelium, 1.4% of the terminal bronchiolar epithelium, and 3% of the tracheal epithelium were made up of brush cells. No brush‐bordered epithelium was found in the lobar bronchi or in the distal alveolar walls. We conclude that brush cells have a distinct spatial location in the lung, being in high concentration in the trachea and in areas where first generation alveolar duets bifurcate. The highest density was on the bifurcation of the first alveolar ducts, and their density decreased radially from this reg

ISSN:0003-276X    

DOI:10.1002/ar.1092160109

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

年代:1986

数据来源: WILEY

摘要:

AbstractThe type II pneumocytes of guinea pigs were studied with a transmission electron microscope. It was shown that 5–20% of type II cells contained filamentary tubular inclusions. No reports of similar structures in type II cells of any species have been found in the literature to date.These inclusions measured 90 nm in diameter, varying up to 3 μm in length, and were generally present in the basal and lateral portions of the cells with a close association to the lamellar bodies. They were usually straight but could be curved and tended to aggregate into parallel stacks. In cross‐sections, these filamentary tubular inclusions were surrounded by a thickened unit membrane and were composed of microfilaments arranged in circular fashion around a central core. In longitudinal sections, they consisted of rod‐like bodies with three lines of filaments.The possible function of the filamentary tubular inclusions is also dis

ISSN:0003-276X    

DOI:10.1002/ar.1092160110

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

年代:1986

数据来源: WILEY

摘要:

AbstractThis study was designed to characterize the ultrastructure and carbohydrate content of secretory cells in submucosal glands of rhesus monkey and to compare this information with that available for humans. The tracheas from five adult monkeys were fixed by airway infusion, processed, and embedded for both light and transmission electron microscopy. Histochemical stains including alcian blue–periodic acid–Schiff, dialyzed iron, and high‐iron diamine‐alcian blue were applied to serial glycol methacrylate sections. The cytochemical stains used included periodic acid‐thiocarbohydrazide–silver proteinate, high‐iron diamine, and low‐iron diamine. The glandular secretory cells were divided into four categories based on ultrastructure and location within the gland. Cells in the first category resembled the mucous cell of the surface epithelium and were located in ducts most proximal to the tracheal lumen. The second category consisted of cells that were located in distal ducts and contained large electron‐lucent granules. The granules in both of these cell groups contained material that was periodate‐reactive and sulfated. Cells of the third category contained granules that were either electron‐lucent or electron‐dense. These cells, which were difficult to characterize as either serous or mucous, were located in secretory tubules and acini and contained periodate‐reactive glyco‐conjugates that were either sulfated or nonsulfated. The last category consisted mainly of cells that contained electron‐dense granules that were lightly periodate‐reactive or a few that were unreactive with any of the cytochemical methods used here. We concluded from this study that 1) the submucosal glands of rhesus monkey contain secretory cells with a variety of morphologies; 2) the secretory cells, which in some cases are not easily identified as mucous or serous, contain material that is periodate‐reactive and sulfated, contain material that is periodate‐reactive only, or contain no carbohydrate as detected by the cytochemical methods used; and 3) the submucosal glands of rhesus monkey trachea resemb

ISSN:0003-276X    

DOI:10.1002/ar.1092160111

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

年代:1986

数据来源: WILEY