摘要:

Abstract“Chronic” axon swellings were produced by applying a snug ligature around the sciatic nerve of rats by the fourteenth postnatal day, allowing the nerve to compress itself by its subsequent growth. The technique results in swelling of the entire myelinated fiber population proximal to the constriction, and in hypoplasia or arrested growth distal to it. “Chronic” axon swellings differed strikingly from the “reactive” axon swellings in the stumps of transected nerves in having normal or slightly below normal concentrations of axoplasmic organelles, including mitochondria and smooth endoplasmic reticulum.Swelling of the axons was associated with attenuation of their sheaths having normal interperiod width but fewer turns of myelin lamellae than found in normal fibers of comparable calibers. Release of the compression resulted in rapid restitution of axon swellings; the excess axoplasm was drained from the fibers and the sheaths rapidly acquired normal thickness. The magnitude of all observed changes in the sheaths of swollen and of restituted fibers was consistent with a rearrangement of the existing turns of myelin lamellae without change in the total amount of myelin. The myelin sheath appears capable of adjusting to both increases or decreases in axon size by slippage of i

ISSN:0003-276X    

DOI:10.1002/ar.1091720101

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

年代:1972

数据来源: WILEY

摘要:

AbstractFrom intramuscular bipolar fine‐wire electrodes in the four heads of quadriceps femoris, electromyographic recordings were made (along with electrogoniometric records) in nine normal men and women during selected postures and movements of the loaded and unloaded knee. Variation between the onset and cessation of activity between the four heads and from subject to subject was found, but the vastus medialis reflected the general pattern of activity rather than acting only terminally during extension. Rectus femoris had the shortest span of activity during extension of the kne

ISSN:0003-276X    

DOI:10.1002/ar.1091720102

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

年代:1972

数据来源: WILEY

摘要:

AbstractThe possibility that chondrocytes of the proximal fragment of Meckel's cartilage may participate in resorption of the extracellular substance of the cartilage and outlive its removal, has been investigatedin vitroandin vivo.Mandibles from 18 dayin uteromouse foetuses were cultured for 14 days on an an antibiotic‐free chemically defined medium. When tested histochemically for acid phosphatase heavy deposits of reaction product were evident in cells in areas where resorption appeared to be occurring. When maintained on medium containing 1.0 μg/ml hydrocortisone, groups of chondrocytes hypertrophied and were reactive for acid phosphatase, and this was accompanied by loss of intervening extracellular substance. These changes were intensified by increasing the oxygen tension of the environment and by further supplementing the medium with 1.0 μg/ml triiodothyronine. Chondrocytes in the vicinity of sites of resorption could incorporate3H‐proline and3H‐thymidine.In vivo, chondrocytes in the vicinity of resorbing areas in two to three daypost‐partumanimals were highly reactive for acid phosphatase, and could incorporate3H‐thymidine,3H‐proline, and3H‐uridine. These observations have been interpreted to suggest that resorption of the proximal fragment of Meckel's cartilage is not necessarily accompanied by death of the chondrocytes, and that the chondrocytes may participate in removal of the extracellular substance. Furthermore, the response of the chondrocytes of Meckel's cartilage to hydrocortisonein vitroappears to differ from the response that has been reported to occur in a number of othe

ISSN:0003-276X    

DOI:10.1002/ar.1091720103

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

年代:1972

数据来源: WILEY

摘要:

AbstractA new cell with relatively little cytoplasm has been identified in the second kind of follicle in the C3H mouse thyroid gland. It has as ultrastructural characteristics the presence of clusters of fiber in the cytoplasm, vesicles near the basal plasma membrane, and half desmosomes in the basal plasma membrane. It resembles the U cell found in the ultimobranchial follicle of the Fischer rat thyroid, but has a somewhat larger amount of granular reticulum. It is found in the follicle wall between other epithelial cells and the basement membrane, but occasionally is in contact with the lumen. It also occurs as a double layer in the follicle wall. Cell debris in the lumen of the follicle contains fibrils and may be the result of desquamation of this fibril‐containing cel

ISSN:0003-276X    

DOI:10.1002/ar.1091720104

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

年代:1972

数据来源: WILEY

摘要:

AbstractLens regeneration was inhibited in adultTriturus v.with 1500 r of x‐irradiation. Implants of irradiated or unirradiated segments of dorsal iris were then implanted into either irradiated or unirradiated eyes. When irradiated eyes received irradiated implants, only minor degrees of lens regeneration were seen from host and implant. Unirradiated eyes receiving unirradiated implants often formed two normal lenses, one from the host and one from the implant. Irradiated eyes receiving unirradiated implants usually formed one normal regenerate arising from the implant. Unirradiated eyes receiving irradiated implants usually formed only one normal regenerate, originating from the host. The results indicate that inhibition of lens regeneration by x‐irradiation is due to effects solely on the iris, and that unirradiated neural retina, under the experimental conditions used, does not stimulate recovery of the regenerative ability of an irradiated iris. These results are discussed in relation to the question of neural‐tissue‐mediated recovery of regeneration systems from x‐ir

ISSN:0003-276X    

DOI:10.1002/ar.1091720105

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

年代:1972

数据来源: WILEY

摘要:

AbstractIn adult sheep, the hepatic sinusoids have an endothelial lining with numerous gaps and fenestrae and are surrounded by a complete basal lamina. In newborn lambs, the sinusoids have a relatively thick endothelium with fewer gaps, and the space of Disse contains a partially formed endothelial basal lamina. In both adult sheep and lambs, perisinusoidal cells appear to form a network around the sinusoid. In portal areas, the endothelium of the smaller capillaries is fenestrated, but the larger capillaries have unfenestrated walls and are enmeshed in processes of pericytes. Projections of endothelial cells partially or completely occlude the lumen of some portal capillaries, and of a large majority of sinusoids scattered throughout the lobule.

ISSN:0003-276X    

DOI:10.1002/ar.1091720106

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

年代:1972

数据来源: WILEY

摘要:

AbstractThe enzymes elastase, chymotrypsin, pepsin, pronase, hyaluronidase, and collagenase were utilized on thin Epon sections to obtain further information on the nature of elastic fibers. Results showed that the central amorphous material was selectively removed by elastase and after hydrogen peroxide pretreatment it also was removed by chymotrypsin, pepsin and pronase. None of the enzymes removed the peripheral microfibrils, but pepsin did accentuate the density and periodic beading of these structures. The failure of proteases to remove the microfibrils under these conditions is discussed.

ISSN:0003-276X    

DOI:10.1002/ar.1091720107

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

年代:1972

数据来源: WILEY

摘要:

AbstractThe culturing of lung tissues in diffusion chambersin vivohas failed to support epithelial elements. The transplantation of lung rudiments into mammary fat pads of mice, however, has allowed long term culture (11 months) with complete differentiation of the explants.

ISSN:0003-276X    

DOI:10.1002/ar.1091720108

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

年代:1972

数据来源: WILEY

摘要:

AbstractA radiographic and histologic study of bat bones showed that there is a progressive loss of bone tissue during hibernation and abrupt reversal at arousal. Enhanced osteolysis accounted for the bone loss; osteoclasia was not observed.

ISSN:0003-276X    

DOI:10.1002/ar.1091720109

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

年代:1972

数据来源: WILEY

摘要:

AbstractThe fate of the granulated metrial cell was studied with the electron microscope. In the degenerating areas of the metrial gland the granulated metrial cells undergo necrosis. The granules of the lysed cells are enclosed by a limiting membrane and their contents appear unaltered. The observations indicate that after the granules are free, the limiting membrane is lost and the contents released into the tissue space. Phagocytic cells are apparently involved in clearing the area of cellular debris. Metrial granules are sometimes engulfed by the phagocytic cells. The “lipid bearing” cells of the metrial gland were also investigated with the electron microscope. These cells contained few organelles, a flocculent cytoplasmic ground substance, lipid droplets, and large dense bodies. The membrane limited dense bodies resemble secondary lysosomes and contain multilaminated myelin whorls plus a variety of dense fibrous or homogeneous material. The release of metrial granules is discussed in relation to the possible secretion of relaxin by metrial cells. The role of the lipid bearing cells is also conside

ISSN:0003-276X    

DOI:10.1002/ar.1091720110

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

年代:1972

数据来源: WILEY