摘要:

AbstractFor many years data on the development of specific antibody‐forming cells in lymph nodes were incomplete, fragmentary, and even contradictory. A number of recent studies have been performed, concerning (1) their overall architecture; (2) migration of B‐lymphocytes; (3) localization of accessory cells and T‐lymphocytes which are believed to be involved in humoral immune responses; and (4) localization patterns of specific antibody‐forming cells developing during thymus dependent and thymus independent immune responses. Comparison of these new results with those of earlier studies suggests a single route of migration followed by all cells which will differentiate into antibody‐forming cells. During their differentiation into antibody‐forming plasma cells, antigen reactive B‐cells migrate along the required accessory cells and/or

ISSN:0003-276X    

DOI:10.1002/ar.1092180402

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

年代:1987

数据来源: WILEY

摘要:

AbstractStructural and functional differences between adult and fetal colonic goblet cells have not been clearly defined. To compare the binding, uptake, and intracellular pathway of internalized apical membrane in fetal and adult goblet cells, cationic ferritin (CF) was used as a nonspecific probe. The initial distribution of membrane anionic sites was determined in segments of proximal and distal colon from fetal (18–22 days) and adult rats that were fixed prior to a 10‐minute exposure to CF at 4°C. Uniform binding along the apical membrane and microvilli was noted at all ages. To assess uptake and intracellular transport, segments of proximal and distal colon from fetal and adult rats were exposed to CF for 10 minutes at 4°C prior to a saline wash and incubation in saline or Liebovitz L‐15 medium for 3, 6, 15, 30, or 60 minutes at 37°C. In addition, fetal rats between 18 and 22 days gestation (birth) were exposed to CF continuously for 10–30 minutes via an intracaecal injection. The results showed extensive uptake of CF in the fetal goblet cells and a more variable intracellular pathway than in with the adult. Within 3 minutes, numerous CF positive vesicles and tubules were present within the apical cytoplasm as well as interspersed among the secretory granules of the fetal goblet cell. Most of these vesicles were smooth surfaced, although some were coated. By 15 minutes, CF was frequently seen in multivesicular bodies, and occasionally in vacuoles in the vicinity of the Golgi. No CF was detected in Golgi cisternae. In contrast to fetal cells, only limited uptake was noted in adult goblet cells and the vesicles were restricted to the periphery of the secretory granule mass. In addition, transport to lysosomes was the exclusive route of these vesicles in the adult. These findings indicate that vesicular uptake is extensive in fetal goblet cells and the intracellular pathway is more variable and less restricted than in

ISSN:0003-276X    

DOI:10.1002/ar.1092180403

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

年代:1987

数据来源: WILEY

摘要:

AbstractThis morphologic study compares the regenerative response in submandibular gland (SMG) autografts placed in the tongues of previously sympathectomized rats to autografts placed in tongues of sham‐sympathectomized rats. We hypothesized that sympathectomy would alter the process of cellular proliferation and inhibit cytodifferentiation in regenerating SMG autografts. Either 1 week, or 8 to 11 weeks following the SMG autografting procedure, the rats were sacrificed and their tongues were removed and sectioned in a cryostat. Frozen tissue sections containing the SMG autografts were either reacted for cholinesterase activity, treated with a glyoxylic acid mixture to induce histofluorescence, or stained for histologic examination. In addition,3H‐thymidine labeled and unlabeled cells were counted in autoradiographs of 1‐week autografts, and these counts were used to calculate labeling indices. The 1‐week SMG autografts from both the sympathectomized and the sham‐sympathectomized rats were similar in histologic appearance, and neither group of autografts contained cholinesterase‐positive or monoaminergic nerve fibers. The 8‐ to 11‐week autografts from sympathectomized and sham‐sympathectomized rats contained cholinesterase‐positive fibers, but monoaminergic fibers were present in the autografts only from the sham‐operated rats. Acinar cells were observed in one‐third of the 8‐ to 11‐week autografts of both the sympathectomized and the shamsympathectomized rats. This finding suggests that sympathectomy did not preclude cytodifferentiation in the autografts. The autoradiographic data revealed no statistically significant difference between the mean labeling indices of the 1‐week autografts from the sympathectomized and sham‐sympathectomized rats, which suggests that sympathectomy also did not alter the level of cellular

ISSN:0003-276X    

DOI:10.1002/ar.1092180404

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

年代:1987

数据来源: WILEY

摘要:

AbstractThe hydroxyapatite crystallites of mammalian enamel appear as hexagons when seen in cross‐sections examined with the transmission electron microscope. Using goniometric transmission electron microscopy, stereo‐pair electron micrographs and freeze‐fracture replicas, two models have been proposed to explain the hexagonal crystallite profile. The “hexagonal ribbon” model proposes that hexagonal profiles are true cross‐sections of elongated hexagonal ribbons. The “rectangular ribbon” model proposes that crystallite profiles are three‐dimensional rectangular segments (parallelepipeds), which are contained in the Epon sections and project as opaque hexagons in routine transmission electron micrographs. Morphological observations together with predictions from models indicate that the crystallites in rat incisor enamel are flat ribbons with rectangular cross‐sectional profiles. The hexagonal images seen in electron micrographs of thin sections of enamel result from viewing parallelepiped‐shaped segments of these crystallites as tw

ISSN:0003-276X    

DOI:10.1002/ar.1092180405

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

年代:1987

数据来源: WILEY

ISSN:0003-276X    

DOI:10.1002/ar.1092180406

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

年代:1987

数据来源: WILEY

摘要:

AbstractMidbelly cross sections of the medial gastrocnemius muscle of young adult male laboratory mice were subjected to ATPase histochemistry with preincubation at pH 4.6. Through the use of a sampling grid and computer‐assisted morphometric analysis, 26 to 35% of the total muscle fibers were sampled and classified as type I, IIa, or IIb.Photomicrographs (16×20 in.) of five muscles were divided into octants according to a standardized procedure. Total fiber counts and percent of fibers sampled were determined. Variability of sample size per octant was noted, but when averaged across entire muscles, it was in all instances greater than 33%. Fiber type frequency per octant was tested for goodness of fit to a random model by means of a chi‐square statistic for equal expected frequencies. Deviation from random fiber type frequency was significant at the P = 0.001 level for every muscle. More importantly, when these data were pooled and again tested using the same method, the probability estimate was less than P = 0.001. This established that the variations in the fiber type proportions found in each mouse followed a common pattern.The systematic fiber type distribution confirmed by these morphometric and statistical methods supports the impression expressed by many muscle biologists that this muscle displays a consistent and complex intramuscular organiza

ISSN:0003-276X    

DOI:10.1002/ar.1092180407

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

年代:1987

数据来源: WILEY

摘要:

AbstractThe extracellular matrix (ECM) of first‐trimester human decidua was examined with indirect immunofluorescence using affinity‐purified antibodies to human collagen types I, III, IV, V, laminin, and fibronectin. In addition, the validity of the classification “mesenchymal‐epithelioid” for differentiated decidual cells was addressed using antibodies to the intermediate filament proteins, vimentin, a mesenchymal marker, and keratin, an epithelial marker. Biosynthesis of extracellular matrix components was examined by radiolabeling of decidual explants in culture with3H‐proline, followed by immunoprecipitations of synthesized proteins with collagen type‐specific antibodies. Immunofluorescence showed decidual cells are embedded in an extensive network of collagen types I and III, and intracytoplasmic staining suggested synthesis of these collagens by the decidual cells. Collagen type IV and laminin localized in the external lamina which surrounds the differentiated decidual cell, and some fluorescence was evident in the peripheral cytoplasm. Immunoreactive collagen type V was observed in close association with the external lamina and in the peridecidual matrix. Fibronectin localized throughout the decidual ECM and in fibrillar and punctuate patterns in the decidual cell cytoplasm. Differentiated decidual cells retained a “mesenchymal” intermediate filament cytoskeleton containing an abundance of vimentin filaments, but very few, if any, keratin filaments. Collagen types I, III, V, and to a lesser extent, IV, were immunoprecipitated from the medium of decidual explants after 24 hours of culture, demonstrating in vitro synthesis and secretion of these collagens by first trimes

ISSN:0003-276X    

DOI:10.1002/ar.1092180408

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

年代:1987

数据来源: WILEY

摘要:

AbstractThe comparative growth patterns of endocrine gastrin and somatostatin cell populations were examined in the rat, during the perinatal period, to investigate possible relationships between their development and that of gastric acid secretion, gastrin and somatostatin hormones being implicated in the regulation of acid secretion. Total cell populations were estimated daily in the pancreas, stomach, and duodenum, by using a quantitative morphological method, from 19 days postcoitum to 8 days postpartum.In the pancreas, both cell types were present at 19 days postcoitum. After increasing, gastrin cells abruptly dropped from 4 days postpartum, while somatostatin cells continued to increase. In the stomach, gastrin cells seemed to appear at 19 days postcoitum, increasing with age. Somatostatin cells appeared only after birth and could be precisely quantified from 4 days postpartum. In the duodenum, the two cell types were present in similar numbers at 19 days postcoitum and increased similarly with age.Comparison of gastrin and somatostatin cell developmental behavior with previous data on the ontogeny of acid secretion shows a parallelism between the appearance of basal H+fluxes at 20–21 days postcoitum and the high daily multiplication of the gastrin cell number in the three organs. Additionally, the marked decrease of pancreatic gastrin cell population at 4 days postpartum and the simultaneous development of the gastric somatostain cell population might explain, among other mechanisms, the diminution of gastric acid secretion noted after birt

ISSN:0003-276X    

DOI:10.1002/ar.1092180409

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

年代:1987

数据来源: WILEY

摘要:

AbstractThe morphology of the carotid sinus region of the internal carotid artery was studied in spontaneously hypertensive rats (SHR) at 5, 8, 16, and 24 weeks of age. The carotid sinus region occupied the proximal millimeter of the internal artery, and was easily recognizable by the presence of an extensive adventitial capillary plexus, which was absent on adjacent arteries (e.g., common and external carotid arteries). Methylene blue‐stained whole‐mount preparations showed the extent of baroreceptor nerves over the sinus. Baroreceptor fibers terminated in distinctive bulbous‐like endings, which, at the ultrastructural level, were filled with mitochondria. No differences were noted in the sinus adventitial capillary network or baroreceptor distribution between SHR and age‐matched Wistar‐Kyoto (WKY) normotensive control animals. With the onset of a significant rise in SHR blood pressure, the carotid sinus wall increased in thickness and total vessel size. The wall/lumen ratios were significantly larger in the SHR than in age‐matched WKY ratios in all age groups. SHR carotid sinus vessel enlargement was uniform throughout the vessel tunics, with no significant change in the proportion of the tunica media occupied by smooth muscle cells. The increase in the carotid sinus wall thickness associated with increasing hypertension could affect the ability of the sinus to distend and may play a secondary role in the maintenance of hypertension by compromising baroreceptor nerve ending

ISSN:0003-276X    

DOI:10.1002/ar.1092180410

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

年代:1987

数据来源: WILEY

摘要:

AbstractIn order to trace tissue movements during septation of the embryonic truncus arteriosus into aortic and pulmonary cardiac outlets, the cephalic margin of the developing tubular heart of chick embryos was tattooed at Hamilton‐Hamburger Stages 20–22 using diffusion micropipettes filled with 0.5% agarose and radioactive macromolecular precursors (tritiated thymidine, uridine, and leucine). Following further incubation for 2, 48, or 96 hours, the locations of such tatoos were determined by autoradiography of sectioned tissue and computer reconstruction of the developing outflow tract.Two hours after tattooing, radiolabeled cells were clustered at the right distal margin of the myocardial tube, as intended. Two days later, during septation of the outflow tract into the two arterial streams, label was concentrated along the posterior margin of the myocardium, between the developing aortic and pulmonary valve anlagen to the embryo's right and left, respectively. Four days following tattooing, as truncal septation neared completion, remaining label was found primarily to the left of the aortic valve ring posterior to the pulmonary outlet. The movements of thymidine tattoos during septation were demonstrated in a series of 31 embryos, 14 fixed at 2 hours, 12 at 2 days, and 5 at 4 days following tattooing; similar results were seen in uridine and leucine labeled hearts.The motion of such tattoos in the developing chick heart suggests that the left side of the definitive semilunar valve ring derives from the right distal margin of the primitive tubular heart and that normal morphogenesis of the great arterial streams involves both retraction and rotation of the embryonic truncus arterio

ISSN:0003-276X    

DOI:10.1002/ar.1092180411

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

年代:1987

数据来源: WILEY