摘要:

AbstractThe retinal photoreceptors of the eye of the American chameleon,Anolis carolinensis, have been considered to be exclusively cones. Its retina is unusual for possessing two foveas (areas associated with heightened visual acuity), with the major, central fovea deeply incised and very densely packed with photoreceptors. Immunoblotting and light‐ and electron microscopic‐immunocytochemistry, using several opsin monoclonal antibodies previously found specific for rods, demonstrated the presence and localization of this protein in theAnolisretina. This visual pigment appears sparsely in a subpopulation of photoreceptors in the periphery but overwhelmingly in the central fovea. Complementary results with cone‐specific antibody and lectin binding corroborated this spatial organization. These results, as well as those with geckos, suggest that photoreceptor morphology is not an accurate guide among the lacertilians to visual pigment content, and that this phylogenetic grouping may constitute a crossoads in vertebrate photoreceptor evolution. © 1993 Wiley‐L

ISSN:0003-276X    

DOI:10.1002/ar.1092370302

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

年代:1993

数据来源: WILEY

摘要:

AbstractThe structural features of the Golgi apparatus of acinar cells of mammary glands were examined with the electron microscope in 3 groups of rats: (1) in lactating female animals at 8 days postpartum, which served as controls; (2) in female rats sacrificed at various intervals from 2 to 30 hours following separation from their 8‐day old pups; and (3) in females separated from their 8‐day‐old pups for a period of 12 hours and returned to their litters for durations of 1, 2, 4, and 8 horus. In animals of group 2, the Golgi stacks remained identical to that of controls between 2 and 8 hours. At 12 hours and later, the Golgi stacks decreased progressively in size, but the number of elements composing the stacks remained similar to that of lactating females and all contained casein submicelles. At 24 and 30 hours, typical secretory granules containing casein micelles disappeared from the trans aspect of the stacks. The earliest and most striking changes observed in the Golgi apparatus of the rats of group 2 took place at 12 hours. At this time, the prosecretory and secretory granules decreased considerably in volume and lost most of their electron‐lucent content. This indicated that the delivery of small molecules, i.e., lactose and H2O, to these structures was soon altered following arrest of the sucking stimulus. In animals of group 3, the size of prosecretory and secretory granules and the amount of their electron‐lucent content reverted to normal at 4 hours. Thus the influx of lactose and H2O into these structures appears to be rapidly restored after returning the pups to their mothers. The decrease in size of the Golgi stacks noted at 12, 18, and 24 hours following arrest of lactation (group 2), was accompanied by an increase in number of small vesicles that formed clusters next to the Golgi stacks and in “wells.” Thus in these regressing Golgi stacks, many of the associated small vesicles appear to arise by vesiculation of the saccules. © 1993 W

ISSN:0003-276X    

DOI:10.1002/ar.1092370303

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

年代:1993

数据来源: WILEY

摘要:

AbstractStriated anchoring fibrils (SAF) are associated with the basement membrane underlying myoepithelial and acinar cells of mammary glands. Their proximal extremities are inserted in electron‐dense areas of the lamina densa, the anchoring plaques seen facing the hemidesmosomes of both myoepithelial and acinar cells. In the case of myoepithelial cells, the hemidesmosomes show a thick cytoplasmic plaque applied to the basal plasma membrane in which cytoplasmic filaments are inserted. Facing this plaque but on the extracellular aspect and at a short distance of 5–10 nm, there is a thin layer of electron‐dense nodular material called the subcell membrane plate, which is connected to the plasma membrane by short filamentous bridges. Between this subcell membrane plate and the anchoring plaque, there is an abundance of fine anchoring filaments crossing the lamina lucida. Such anchoring filaments are less abundant in the lamina lucida outside the hemidesmosomal areas. In the case of acinar cells, the cytoplasmic plaques of the hemidesmosomes are thin and the associated cytoplasmic filaments less conspicuous. No distinct subcell membrane plate is seen on the extracellular aspect of the plasma membrane facing the cytoplasmic plaque of the hemidesmosomes. However, in this area numerous anchoring filaments cross the lamina lucida between the plasma membrane and the SAF‐anchoring plaque complex. The abundance, in these cells, of hemidesomomes and their association with SAF‐anchoring plaque complexes seen in the basement membrane must constitute a strong attachment for both myoepithelial and acinar cells and bind them to the underlying collagen fibrils, thus preventing their detachment from the connective tissue during the contractions of myoepithelial cells during milk ejection. © 1993 Wiley

ISSN:0003-276X    

DOI:10.1002/ar.1092370304

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

年代:1993

数据来源: WILEY

摘要:

AbstractAttempts to increase bone volume in osteoporotic patients are still in the experimental stage. The coherence therapy, proposed by Frost, suggests that the activated bone units can remodel bone matrix in tandem. The cells (i.e., osteoclast and osteoblast which compose the remodeling units) are manipulated through specific medications timed to each of their duration of actions. The current study was to examine the effect of withdrawal of oral phosphate on bone in ovariectomized dogs.The present report demonstrates the capability of short‐term oral phosphate to activate bone remodeling in the ovariectomized animal model. Results from biochemical and histomorphometric analyses confirm that remodeling units are activated following the release of parathyroid hormone. This transient scenario inflicts a shift of mineral density distribution in cancellous bone matrix of the iliac crest. Nevertheless, the bone remodeling units appear to be synchronized with each other and thus their resorptive and formative phases should be amenable to further pharmacological manipulation. © 1993 Wiley‐Liss,

ISSN:0003-276X    

DOI:10.1002/ar.1092370305

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

年代:1993

数据来源: WILEY

摘要:

AbstractEndothelin‐1 (ET‐1) localization in bone cells and associated vascular endothelial cells in metaphyseal bone marrow of the rat femur was examined by a biotin‐streptoavidin‐horseradish peroxidase method in paraffin sections and by indirect immunogold techniques in post‐embedded ultrathin sections. Mouse anti‐ET‐1 monoclonal antibody was used as the primary antibody. In metaphyseal bone marrow, intense immunostaining was observed over osteoclasts, osteoblasts, young osteocytes, and vascular endothelial cells. But bone and cartilage matrices and chondrocytes in the proliferating zone were negative for immunoreaction. At the subcellular level, specific immunogold labeling was localized along plasma membranes and in the cytoplasm including those of ruffled borders and clear zones of osteoclasts. Some colloidal gold particles were also detectable within pale vacuoles of osteoclasts. Immunoreactivity was also found along the plasma membranes, cisterns of rough‐surfaced endoplasmic reticulum, mitochondria, and cytoplasmic matrices of osteoblasts, but was less intense than that of osteoclasts. In endothelial cells of blood capillaries in close proximity to bone cells, intense immunolabeling occurred over the cytoplasm. None of the cases examined showed accumulation of immunogold particles in the secretion granules of these cells. © 1993

ISSN:0003-276X    

DOI:10.1002/ar.1092370306

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

年代:1993

数据来源: WILEY

摘要:

AbstractThree‐dimensional cytoarchitecture and types and features of muscle fibers were examined in soleus muscles from mdx mutant mice at different stages of development. In the 2‐week‐old mice, no abnormal muscle fibers were observed light microscopically, whereas in the 4‐week‐old animals, disrupted fibers were frequent in light microscopy and scanning electron microscopy. Muscle fibers fused with several short fiber branches appeared at the sixth week after birth and increased in number until the tenth week. In the 1‐year‐old mice, approximately ten or more muscle fibers were seen fused together. They had many complex branches forming an “anastomosing syncytial reticulum.” Muscle fibers with irregular diameters and aggregations of the same type fibers were also observed.Our results demonstrated that these complex branched fibers might be formed by long term repetition of the degeneration and regeneration cycle during the development of soleus muscles, indicating that the characteristic features of muscle fibers with irregular diameters and aggregations of the same type fibers are certainly dependent on the existence of the complex branched fibers. © 19

ISSN:0003-276X    

DOI:10.1002/ar.1092370307

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

年代:1993

数据来源: WILEY

摘要:

AbstractIn spite of a decline in muscle strength with age, the cause of the overall decrease in motor performance in aged mammals, including rodents, is incompletely understood. To add clarity, the gross organization, innervation, histochemical fiber types, and age‐associated changes are described for mouse forearm muscles used in a variety of motor functions. The anterior (flexor) and posterior (extensor) forearm compartments have the same arrangement of muscles and gross pattern of innervation as the rat. Two primary histochemical fiber types, fast/oxidative/glycolytic (FOG) and fast/glycolytic (FG), with characteristic hitsochemical staining patterns were observed in all forearm muscles. Additionally, there was a small population of slow/oxidative (SO) fibers confined to the deep region of a single muscle, the flexor carpi ulnaris (FCU).Between 18 and 26 months the FCU muscle displayed fibers with morphological features distinct from earlier ages. Fibers displayed a greater variation in size, a loss of their uniform polygonal shape, and a dramatic increase in clumps of subsarcolemmal mitochondria, lysosomes, and lipofuscin granules. Many of the fibers had a distinctly atrophic, angular shape consistent with recent denervation. Morphometric analyses of the FCU's source of innervation, the ulnar nerve and one of its ventral roots (C8), were consistent with the denervation‐like changes in the muscle fibers. Although, there was no net loss of myelinated axons between 4 and 26 months of age, there was a significant increase in the density of degenerating cells in both the ulnar nerve and ventral root C8. © 1993 Wiley‐Lis

ISSN:0003-276X    

DOI:10.1002/ar.1092370308

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

年代:1993

数据来源: WILEY

摘要:

AbstractThree‐dimensional organization of vesicles was examined to elucidate the transendothelial transport properties for macromolecules in rat aortic endothelium using ultrathin serial sections and horseradish peroxidase (HRP) as a tracer molecule. A total number of reconstructing vesicles was 1,298 in nine series electron micrographs, if each vesicular entity was counted as one regardless of composite number of vesicles. The vesicles could be classified into the following six types: HRP‐positive luminal, abluminal and intercellular invaginations; HRP‐positive channels; HRP‐positive and ‐negative vesicles. The vesicular invaginations and the channels occupied 97.8% and 0.9% of the total vesicles, whereas HRP‐positive and ‐negative free vesicles were found in 0.8% and 0.5%, respectively. The average numerical density of the luminal invagination was 41.1/μm2and approximately equal to that of the abluminal invagination (42.0/μm2), whereas the frequency of the latter was 1.4 times higher than that of the former since the abluminal surface of the endothelium was more irregular to increase a surface area. Each endothelial region varied in the vesicular density and the peripheral region generally showed the higher density, although the transendothelial channels composed of vesicles were not always found in every peripheral region. These results suggest that the shuttle hypothesis is unsuitable to explain “vesicular transport” in the arterial endothelium as well as in the capillary endothelium and that the channels in the peripheral region mainly control transendothelial transport for macromolecules via vesicles. ©

ISSN:0003-276X    

DOI:10.1002/ar.1092370309

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

年代:1993

数据来源: WILEY

摘要:

AbstractThe effects of a maternally administered synthetic glucocorticoid, betamethasone, on the levels of mRNA for the surfactant proteins SP‐A, SP‐B, and SP‐C and on the levels of SP‐A protein were investigated in day 27 gestational age rabbit fetal lung tissue. Betamethasone administration to the pregnant rabbit caused approximately a twofold increase in the fetal lung level of SP‐A protein and a threefold increase in fetal lung SP‐A mRNA levels when compared to levels in fetuses obtained from saline‐treated or uninjected animals. SP‐B mRNA was increased fourfold in fetal lung tissue obtained from glucocorticoid‐treated pregnant does when compared to levels in fetuses of uninjected pregnant does. However, SP‐B mRNA levels in fetal lung tissue from saline‐injected controls were also significantly elevated, ∼twofold, when compared to fetal lung SP‐B mRNA levels in the uninjected control condition. SP‐C mRNA levels in lung tissue of fetuses from both saline‐injected and betamethasone‐injected pregnant does were increased similarly, ∼twofold, over SP‐C mRNA levels in fetal lung tissue obtained from uninjected control does. These data are suggestive that betamethasone treatment increases fetal lung SP‐A and SP‐B mRNA levels and that maternal stress alone can increase the expression of SP‐B and SP‐C mRNA in rabbit fetal lung tissue. Using in situ hybridization, SP‐A mRNA was shown to be present primarily in alveolar type II cells in fetuses of control and saline‐injected does. However, SP‐A mRNA was easily detected in both alveolar type II cells and bronchiolar epithelial cells of rabbit fetal lung tissue following maternal betamethasone treatment. In contrast, SP‐B and SP‐C mRNA were present only in alveolar type II cells of lung tissue obtained from fetuses of control, saline, or betamethasone‐treated does. Thus maternal administration of glucocorticoids increased SP‐A protein as well as SP‐A and SP‐B mRNA levels in rabbit fetal lung tissue. SP‐A mRNA was localized to both alveolar type II cells and in smaller amounts in bronchiolar epithelial cells of rabbit fetal lung tissue. However, SP‐B and SP‐C mRNA w

ISSN:0003-276X    

DOI:10.1002/ar.1092370310

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

年代:1993

数据来源: WILEY

摘要:

AbstractThe time of appearance of the truncus arteriosus was studied in the chick embryo using an in ovo labeling technique. Three hundred embryos at stages 13–18 of Hamburger and Hamilton were selectively labeled at the distal end of the heart tube, using gelatine‐india ink label; 122 of these embryos were reincubated and 111 of them reached stages 25–28. In these stages the final location of the label was determined. Only 95 of these embryos showed both a normal heart and a label located in it. The remaining embryos were discarded due to abnormal cardiac morphology or because the label was not found. Embryos labeled at stages 13–14 had label in the conus in 42.8% of the cases and in the boundary between the conus and the truncus arteriosus in 57.1% of the cases. Label placed at stages 15–16 was located in the conus in 6.1% of the cases, in the boundary between the conus and the truncus arteriosus in 44.8% of the cases, and in the truncus arteriosus in 48.9% of the cases. Finally, label placed at stages 17–18 was located in the boundary between the conus and the truncus arteriosus in 18.7% of the cases and in the truncus arteriosus in 81.2% of the cases. Our results permit us to conclude that the truncus arteriosus appears in the chick embryo as early as stages 15–16 of Hamburger and Hamilton (50–56 hours of incubation). © 1993

ISSN:0003-276X    

DOI:10.1002/ar.1092370311

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

年代:1993

数据来源: WILEY