摘要:

AbstractExperimental bipedalism in rats has been proposed as a model for studying evolutionary and orthopedic change. This study quantified the skeletal changes which occur in the hindlimbs of these bipedal rats. Bipedalism was produced in 16 male rats by forelimb amputation during the neonatal period. The rats were sacrificed at maturity and the femurs and tibia‐fibulas from randomly selected hindlimbs were weighed and measured. Out of a total of 25 parameters, only one, anteroposterior diameter of the proximal femur, was found to differ statistically between the bipedal and control groups. No changes were found in bone length, weight, or curvature. The results of other bipedal studies were reviewed, in light of these findings; and it is concluded that rats do not achieve true bipedalism, or increased hindlimb loadin

ISSN:0003-276X    

DOI:10.1002/ar.1092180102

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

年代:1987

数据来源: WILEY

摘要:

AbstractThe synthesis, intracellular translocation, and secretion of mannose‐containing glycoproteins(s) by periodontal ligament fibroblasts have been investigated by means of electron microscopic radioautography. Tritiated mannose was administered to young mice via jugular vein, and radioautographs were prepared at 5, 10, 20, and 35 minutes, 4 and 8 hours after injection. Analysis of electron microscopic radioautographs revealed a maximum labeling (94%) with3H‐mannose of the rough endoplasmic reticulum at 5 minutes. Labeling of the Golgi components started to increase from 10 minutes (14%) and reached a maximum level at 20 minutes (31.2%). At 35 minutes, secretion granules, dense bodies, profiles of intracellular collagen, and the cell surface were labeled. At 8 hours, most labelling (79.2%) was extracellular, and associated either with the collagenous matrix (43.7%) or the cell surface (35.5%). Cytoplasmic vesicles containing dense materials around collagen fibrils were also labeled at 8 hours. It is concluded that mannose is directly incorporated into the rough endoplasmic reticulum (RER), and that mannose‐containing glycoprotein(s) are packaged in the Golgi apparatus into secretory granules. Mannose‐containing glycoproteins(s) become distributed on the periodontal ligament (PDL) fibroblast cell surface, cytoplasmic dense bodies, and the extracellular

ISSN:0003-276X    

DOI:10.1002/ar.1092180103

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

年代:1987

数据来源: WILEY

摘要:

AbstractThe extraocular muscles in a mutant microphthalmic strain of rat were studied. The eyeball of this strain of rat is reduced to about a third in diameter of that of the normal rat. Nevertheless, in the orbit of the mutant rat, every one of the extraocular muscles was identified; their origins and courses were the same as in the normal rat, but differences existed in the insertions. These insertions could be classified into three groups: Group A (retractor bulbi): like normal insertion into the eyeball. Group B (superior rectus and superior oblique): attachment of tendonlike insertions to each other; these muscles come from opposite directions and form a loop. Group C (lateral, medial, and inferior rectus and inferior oblique): insertion into connective tissue surrounding the reduced eyeball.The volume of each muscle of the mutant rat was smaller than that of the normal rat; moreover, significant differences existed in the degree of reduction in the volume of each muscle group classified according to the change of insertion. In the group A muscle the volume was only 33% of the normal volume, whereas group B was 74% and group C was about half of normal.

ISSN:0003-276X    

DOI:10.1002/ar.1092180104

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

年代:1987

数据来源: WILEY

摘要:

AbstractIn this study, we describe the distribution of actin filaments in and around spermatids that are mechanically dissociated, in the presence and absence of exogenous trypsin, from the seminiferous epithelium of the rat. NBD‐phallacidin and subfragment 1 of the myosin molecule (S‐1) are used as probes for filamentous actin at the light and electron microscopic levels, respectively.The fluorescence associated with spermatids mechanically dissociated in the absence of trypsin is due to actin both in the spermatogenic cells themselves and in attached Sertoli cell ectoplasmic specializations. Fluorescence generated by labelled actin in ectoplasmic specializations occurs in linear tracts that follow the outer contour of spermatid heads. The residual flourescence seen when trypsin is used to detach Sertoli cell fragments is diffuse and due to f‐actin in the subacrosomal space. Electron microscopic data agree with the fluorescence results.This study conclusively demonstrates that Sertoli cell ectoplasmic specializations remain attached to spermatids mechanically dissociated from the seminiferous epithelium. This observation may be useful when attempting to isolate ectoplasmic specializations for biochemical ana

ISSN:0003-276X    

DOI:10.1002/ar.1092180105

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

年代:1987

数据来源: WILEY

摘要:

AbstractThe arrangement of arteries in the mesentery in pigs was studied with latex casts and light microscopy. Arterial arcades, which are characteristic of the mesentery in man and other species, are absent. Instead, a narrow band of numerous, anastomosing arteries gives rise to up to about 500 bundles of arteries and accompanying veins, which radiate out in the mesentery. Each bundle contains up to 30 arteries, but these recombine as they approach the jejunum, and form 1–4arteriae rectae.The significance of the very large number of small arteries in the mesentery is not known, but they may play a role in the control of blood pressure in the intestinal wall, or as sites of countercurrent exchang

ISSN:0003-276X    

DOI:10.1002/ar.1092180106

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

年代:1987

数据来源: WILEY

摘要:

AbstractIn the late prenatal stage, the rabbit corpora cavernosa penis (cavernous bodies) are occupied by a large number of mesenchymal cells actively proliferating by mitosis. Most profiles of the cavernous sinuses show growing capillaries consisting of immature endothelial cells and enclosing a narrow lumen. Such growing capillaries are often associated with the mesenchymal cells that contact with each other and eventually with the endothelial cells.Between 1 and 7 postnatal days, the capillary network develops extensively and the maturation of the capillaries results in a flattened endothelium with a continuous basal lamina. The mesenchymal cells are also associated with the helicine arterial sprouts at this time period. No endothelial mitotic figures were observed within the growing capillaries in pre‐ and postnatal specimens examined.Single pulse labeling with3H‐thymidine in the postnatal rabbits demonstrates that the labeled endothelial cells of the growing capillaries increase in number at 48 hours after injection compared with those at 24 hours, whereas the labeled mesenchymal cells inversely decrease in number.These findings indicate that the incorporation of the mesenchymal cells as vesselforming cells into the growing capillaries accelerates the neovascularization in the rabbit cavernous bod

ISSN:0003-276X    

DOI:10.1002/ar.1092180107

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

年代:1987

数据来源: WILEY

摘要:

AbstractEarlier studies established that stroke‐prone spontaneously hypertensive rats (SHRSP) invariably infarct after middle cerebral artery (MCA) occlusion. Normotensive rats are usually protected from infarction after the occlusion. Objectives of this study were to characterize the anastomosing collaterals that may determine the different outcomes to MCA occlusion in SHRSP and Wistar Kyoto rats (WKY). Young (5–10 week) and old (40–69 week) rats of each sex were anesthetized, then administered papaverine to produce maximal vasodilatation of the cerebrovascular bed. Under control conditions latex was injected into the arterial tree to measure the internal diameter of branches of the anterior cerebral artery (ACA), the MCA, and the ACA‐MCA anastomosing collaterals. Large diameter ACA and MCA rami in old, but not young, SHRSP were significantly smaller in diameter than the respective ACA and MCA branches in old WKY. The number of ACA‐MCA anastomoses was the same for SHRSP and WKY. Mean internal diameter of the ACA‐MCA anastomoses was significantly (p<0.0001) smaller in SHRSP than WKY in both age groups. There were significant negative correlations between age and (1) the internal diameter of the ACA‐MCA anastomoses in WKY but not SHRSP, and (2) the largest diameter ACA and MCA rami in SHRSP but not WKY. The findings suggest that vascular resistance of fully relaxed collaterals is greater in SHRSP than WKY, thereby compromising the dorsal collateral circulation before large diameter vessel changes occur that accompany the established form of

ISSN:0003-276X    

DOI:10.1002/ar.1092180108

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

年代:1987

数据来源: WILEY

摘要:

AbstractLight and electron microscopy were used to study the structure and distribution of thin collagenous septa (sheets) in dog and rabbit cardiac muscle to determine whether they, like thick collagenous septa, could affect electrical impulse propagation. Generally, thin septa (0.2–0.5 μm) ensheathed myocytes or groups of myocytes for short distances and thicker septa partially or completely ensheathed groups of myocytes for long distances (up to several mm); together, thin, and thick septa divided the myocardial mass into myocyte cords (funicles) of 10–30 μm diameter. Septal architecture varied not only between regions and within regions at different ages but also within single bundles, precluding the assumption that the architecture found in one bundle can be applied to another. Electron microscopy demonstrated that thick septa consisted of many tightly packed collagen fibrils, often with distinct layers running at different angles; thin septa consisting largely of circumferential collagen fibrils. Thin septa in dog ventricular papillary muscle generally contained few and widely spaced collagen fibrils, whereas thin septa in dog atrial Bachmann's bundle contained tightly packed collagen fibrils. In either site, thin septa were rarely breached by nexuses and thus marked sites where lateral intercellular electrical coupling was unlikely. Serial 7 μm cross sections of dog Bachmann's bundle stained by a modification of the picrosirius red technique showed that thin septa sometimes persisted uninterrupted over several myocyte lengths. The results provide evidence that thin septa comprimised of tightly packed collagen fibrils may significantly modify impulse propagation transverse to the longitudinal axis of the my

ISSN:0003-276X    

DOI:10.1002/ar.1092180109

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

年代:1987

数据来源: WILEY

摘要:

AbstractBiopsies of the pancreas head, tail, and uncinate regions of 6 Chacma baboons (Papio ursinus) were processed for ultrastructural and immunocytochemical (ICC) studies using avidin‐biotin peroxidase label for light microscopy (LM) and immunogold for electron microscopy (EM). Survey 0.5 μm sections of Spurrs resin embedded tissue revealed areas of suitable islets. Thin 100‐nm sections were then cut and stained from the osmicated blocks for ultrastructural studies. For ICC investigations, 1 μm sections were immunolabeled for LM before areas were selected for thin sectioning for ultrastructural immunolabeling.The baboon endocrine pancreas ultrastructure was found to be similar to that of other mammals with minor differences in islet and secretory granule size and shape and in electron opacity of the secretory granule cores. Insulin glucagon, somatostatin and pancreatic polypeptide (PP) producing cells were described. A small number of cells were seen to contain both glucagon and PP and some D cells were observed to contain a few granules with both the appearance and immunoreactivity of A cell secretory granules.Statistical analysis of 100 secretory granule diameters of each of the 4 cell types in 6 baboons revealed significant differences (p<0.001) in size between all but those of the A and D cells.The insulin precursor subunit, C‐peptide, and the glucagon precursor, glicentin, were each found together with the final hormone product in their respective secretory granules. The precursors were often located toward the periphery of the secretory granule, suggesting that the conversion of precursor to active hormone may be membrane associated.A nonrandom topographical association was observed between A and D cells, suggesting a strong functional impl

ISSN:0003-276X    

DOI:10.1002/ar.1092180110

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

年代:1987

数据来源: WILEY

摘要:

AbstractEarly cytodifferentiation of human fetal mammary gland was studied at the time of the beginning of the sexual differentiation during the sixth to eleventh developmental weeks. The gland appeared as a solid epithelial ingrowth into the underlying mesenchyme on both sides of the thoracic wall at the age of 5 weeks in both sexes. These ingrowths contained primitive glycogen‐rich cells with large nuclei. The surrounding mesenchymal cells gathered around the basal lamina. These cells differentiated into fibroblasts, and collagen fibers were seen in the mesenchyme near the mammary buds. No lumina appeared within the buds during this study. Differences between the male and female mammary epithelium or mesenchyme were not observed, although androgen synthesis and secretion in the fetal testis had already begun. The close connections and concomitant differentiation of the mammary bud epithelium and mesenchyme during the early embryogenesis in this study suggest that epithelio‐mesenchymal interaction plays an important role in the differentiation of human mammary gl

ISSN:0003-276X    

DOI:10.1002/ar.1092180111

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

年代:1987

数据来源: WILEY