摘要:

AbstractThe role of biogenic amines in the activation of thyroid follicu‐lar cells by thyrotropin (TSH) was studied. 5‐hydroxytryptamine (5‐HT) was chosen as the amine to study and apical pseudopod formation, assessed by scanning electron microscopy, was used as the index of follicular cell activation. All experiments were done on dogs. TSH and 5‐HT were both potent inducers of pseudopod formation. The action of TSH but not that of 5‐HT was antagonized by the amine depleting drug reserpine. Reserpine depleted the thyroid of 5‐HT in newborn, adolescent, and adult dogs. It is concluded that one or more biogenic amines, such as 5‐HT, are probably involved in follicular cell acti

ISSN:0003-276X    

DOI:10.1002/ar.1091920202

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

年代:1978

数据来源: WILEY

摘要:

AbstractIn light of previous evidence that epithelial influences are required for membrane bone formation in certain instances (mandible, Tyler and Hall, '77 a,b; cranium, Benoit and Schowing, '70), the possibility that maxillary epithelium influences membrane bone formation within the maxillary mesenchyme was investigated. Intact maxillary processes, and enzymatically separated epithelial and mesenchymal components of the maxilla were obtained from embryonic chicks of three to five days of incubation (Hamburger and Hamilton ['51] stages (HH) 18‐25) were grown individually as grafts on the chorioallantoic membranes of host chick embryos. The histodifferentiation of grafted intact maxillary processes was similar to that in vivo. The histodifferentiation of grafted maxillary mesenchyme depended upon the embryonic age at which the mesenchyme was isolated from its epithelium. In grafts of maxillary mesenchyme isolated from its epithelium at HH 22 or earlier stages, cartilage differentiated, but membrane bone did not form. In grafts of maxillary mesenchyme isolated from its epithelium at HH 23 or later stages, membrane bone formed in addition to cartilage. The results indicate that maxillary mesenchyme requires the presence of epithelium through HH 22 in order for membrane bone to form within the mesenchyme. Cartilage formation within the mesenchyme does not require epithelial influences during the embryonic period tested (HH 18‐25). Maxillary epithelium isolated from its mesenchyme and grown as a graft became underlaid by host fibroblasts and achieved a limited degree of differentiation; the epithelium did not induce ectopic membrane bone formation within the host tissue, indicating that the presence of maxillary epithelium is not a sufficient condition for promoting membrane bone formation in normally non‐osteogenic t

ISSN:0003-276X    

DOI:10.1002/ar.1091920203

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

年代:1978

数据来源: WILEY

摘要:

AbstractThe ability of the mammary gland to take up and organically bind radioiodide was studied in non‐pregnant, pregnant, and lactating rats. Autoradiography was used to determine whether duct cells or alveolar cells are responsible for iodination in the rat mammary gland. Iodination was not detected in mammary glands from non‐pregnant rats, but occurred late in the twelfth day of gestation and continued throughout pregnancy and lactation. Protein‐containing vacuoles in alveolar cells and casein‐like proteins in milk were the major sites where iodination occurred within the gland. Milk proteins in the lumens of ductules adjacent to alveoli were also iodinated. In contrast, ducts, myoepithelial cells, fat cells, blood vessels and other histological components of the gland did not show iodinating capability. Cytochemistry was also used to identify endogenous mammary peroxidase activity in the same glands, and it was found that the presence and location of this enzyme was correlated with the ability to i

ISSN:0003-276X    

DOI:10.1002/ar.1091920204

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

年代:1978

数据来源: WILEY

摘要:

AbstractEpithelial cells of the several subtypes that comprise the small‐granule cell population of the respiratory system are little studied, partly because adequate silver, monoamine fluorescence and other specific light microscopical preparations have been more difficult to obtain than in the gut and other organs possessing diffuse endocrine systems. Periodic acid‐Schiff (PAS) in combination with MacConaill‐Solcia's lead hematoxylin has in our hands proven dependable for routine staining of serial 2‐m̈m glycol methacrylate sections used in mapping the distributions of these cells along the airway. In lungs of mice, hamsters, kittens, and fetal rabbits, typical small‐granule cells stain weakly or not at all with lead hematoxylin alone, hence are easily overlooked. PAS adds to the cytoplasm a diffuse magenta coloration; and because it is diastase‐resistant, less brilliant than that of mucus but more so than bronchiolar cell secretions, and finer textured than lysosomal staining of other cells present, the effect is to highlight small‐granule cells whether solitary or in clusters. Additional PAS staining of basement membranes and lead hematoxylin staining of cilia enhance the combined stain's resolving power. In thyroid gland, parafollicular cells stand out boldly against follicular elements; in small intestine, hematoxylin‐positive endocrine cells are well differentiated from absorptive, mucous, and Paneth cells that surround them. Using a complementary monoamine fluorescence technique on plastic sections of lungs from control and 5‐hydroxytryptophan‐pretreated animals prior to staining, we can show that fluorescent epithelial cells are identical with those stained by P

ISSN:0003-276X    

DOI:10.1002/ar.1091920205

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

年代:1978

数据来源: WILEY

摘要:

AbstractTo determine whether filtration in reconstituted perifollicular marginal zones underlies particle sequestration in regenerating spleen transplants, the distribution of IV injected particles of tantalum was examined in autografts freely transplanted into subcutaneous pouches in rats. In two to six weeks old autografts removed one to three hours after particle injection, the reconstituted marginal zones contained practically all of the sequestered tantalum. At 48 hours to‐20 weeks following injection, marginal zones were largely free of particles which were distributed extracellularly throughout the red pulp. This sequential pattern of distribution conformed closely to that observed in the intact spleen.The findings indicate that a reconstituted marginal zone allows splenic autotransplants to function as simple mechanical filters. Increased demand for this activity rather than for phagocytosis may be the predominant factor regulating spleen growt

ISSN:0003-276X    

DOI:10.1002/ar.1091920206

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

年代:1978

数据来源: WILEY

摘要:

AbstractA freeze‐fracture study has revealed rod‐shaped intramembra‐nous particles on the plasma membrane P‐face (cytoplasmic leaflet) of the mi‐tochondria‐rich cell (or flask cell) ofXenopus laevisandRana ridibundaepidermis. Such particles have previously been found in all other mitochondria rich cells examined by this technique, namely, the MR‐cell of toad bladder epi‐thelium, the dark cèll of rat kidney collecting tubule, and the flask cell of Xenopus kidney collecting tubule. These particles are assumed, therefore, to be closely connected with the function o

ISSN:0003-276X    

DOI:10.1002/ar.1091920207

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

年代:1978

数据来源: WILEY

摘要:

AbstractThe ultrastructural changes in hepatocytes of rats subjected to selective biliary obstruction (SBO), wherein the biliary system draining approximately two‐thirds of the liver is obstructed, were evaluated by quantitative electron microscopy or stereology. The remaining unobstructed portion of the organ compensates for this loss of bile secretion by functioning in a hyper‐secretory mode. This animal model permits the comparison of hepatocellular fine structure associated with the conditions of nonsecretion and hypersecre‐tion of bile with that found in normal secreting sham‐operated rats. Since recent evidence suggests the presence of lobular gradients in hepatic structure and function, both centrolobular and periportal hepatocytes were examined. The low incidence of Golgi membrane profiles in high magnification electron micrographs results in a low confidence level of sampling and, thus, necessitates the application of a novel parameter for estimating the amount of Golgi complex, i.e., the Golgi‐rich area.For the most part, the lobular variation in hepatic fine structure in the sham‐operated animals was similar to that described by Loud ('68). However, the periportal parenchyma contained approximately twice the volume of Golgi‐rich area as the centrolobular tissue. The amount of cytoplasmic lipid increased significantly in the SBO unobstructed lobes, although there were few or no changes in the other intracellular organelles or inclusions except those related to the Golgi complex. The volume of Golgi‐rich area increased significantly in the centrolobular tissue of the SBO unobstructed (hypersecretory) lobes to the extent that both intralobular zones contained similar amounts of this component. These data suggest that the Golgi complex is a dynamic unit which responds to changes in hepatocellular activity and may be involved in

ISSN:0003-276X    

DOI:10.1002/ar.1091920208

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

年代:1978

数据来源: WILEY

摘要:

AbstractThe tail bud was completely extirpated down to the yolk from 65 embryos at stages 13‐17 to determine whether the posterior part of the noto‐chord originates from the tail bud or from a more anterior region (i.e., prospective notochordal region). About 40% of the 44 surviving embryos developed near‐normal tails, con̈taining a localized defective region beginning near the base of the tail and extending a short distance posteriorly, about 15% developed truncated, cone‐shaped tails, containing a defective region beginning near the base of the tail and extending towards the tip, and about 45% developed short, ventral tail remnants, containing a localized defective region beginning near the base of the tail and extending a short distance posteriorly. The tail was absent in only one embryo. These differences were probably due primarily to variation in the amount of healing and regeneration that occurred, and were independent of the stage at which the operation took place. The tail region has a tremendous capacity for regeneration since a near‐normal tail frequently developed. The location of the beginning of the defective region near the base of the tail suggests that the tail bud primarily gives rise to tail structures. All embryos had neural tube defects, about 30% developed large, midline somites within the defective region, and about 25% developed an ourenteric outgrowth. The notochord was always normal within the defective region. These results are consistent with the view that the tail bud contributes cells to the posterior part of the neural tube, butnotto the

ISSN:0003-276X    

DOI:10.1002/ar.1091920209

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

年代:1978

数据来源: WILEY

摘要:

AbstractFreeze‐fracture of rat gastric mucosa revealed a specific set of intramembranous particles in the plasma membrane of the parietal cells. The particles were small and of square shape and formed orthogonal arrays in the P‐face with corresponding orthogonal arrays of pits in the E‐face. Arrays, scattered among usual globular particles, were particularly numerous at the basal pole of the cell and less concentrated on the lateral side. They were not present in the apical microvillar membrane nor in the membranes of intracellular tubulovesicles. As in other cell types in which similar arrays were described previously (e.g., astrocytes, “light” cells of the kidney collecting tubule), their presence in parietal cell membranes suggest some specialized function of these membranes not shared by plasma membranes showing only a population of globular particles. This function has yet to be i

ISSN:0003-276X    

DOI:10.1002/ar.1091920210

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

年代:1978

数据来源: WILEY

摘要:

AbstractIn an attempt to determine the pattern of collagen phagocy‐tosis by fibroblasts in the periodontal ligament, a stereologic investigation of the mesial root of the maxillary first molar of the rat was undertaken. The distribution of fibroblasts containing intracellular collagen fibrils was studied at the electron microscope level in the periodontal ligament along resorbing and non‐resorbing surfaces of the alveolar wall. It appeared that fibroblasts with collagen‐containing vacuoles were more or less randomly distributed across the width of the periodontal ligament. No major differences were observed among the alveolar, cemental and intermediate zones of the ligament. However, local variations in the occurrence of cells containing intracellular collagen fibrils may occur. A relatively high concentration of ingested collagen fibrils was seen in fibroblasts located in the direct vicinity of osteoclasts, but not in the vicinity of osteoblasts. These observations suggest that remodelling of collagen is even‐ly distributed throughout the ligament, but may be influenced by local circumstances, such as the occurrence of bone res

ISSN:0003-276X    

DOI:10.1002/ar.1091920211

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

年代:1978

数据来源: WILEY