摘要:

AbstractThe weight, density and percentage ash weight of the dry, fat‐free osseous human skeleton have been examined from 16 weeks of gestation to 100 years of age. Data were drawn from 426 skeletons of American Whites and Negroes of both sexes.Weight increases exponentially in the fetus and continues to increase to early adulthood, most rapidly in the second decade. A decrease appears about the fourth decade and continues gradually. Estimated loss in skeletal weight throughout the adult period is, on the average, 15.6 gm per year. Proportionate contributions of divisions of the skeleton to its total weight change with age.Densities of bones follow the changing weight pattern. Volume and weight increase concomitantly to adulthood, when weight decreases but not volume.Percentage ash weight increases slightly in the total skeleton and in some bones during the fetal period, with no significant trend thereafter, indicating that change in weight of a dry, fat‐free bone is accompanied by change in ash weight.Race and sex differences are not evident in the fetal skeleton, but become marked by the second decade of life: Negro skeletons exceed White skeletons and male skeletons exceed female skeletons in mean weight and density and, to a lesser degree, in percentage ash wei

ISSN:0003-276X    

DOI:10.1002/ar.1091790102

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

年代:1974

数据来源: WILEY

摘要:

AbstractA parental (CBAT6T6) lymph node cell suspension was injected into the hind footpad of F1(CBA × C57BLKs) recipients. The resulting increase in the recipient's popliteal lymph node weight was linearly related on double log plots to the number of parental lymph node cells injected. The node weight response was biphasic including an initial rise, a maximum weight gain at seven to nine days and a gradual decline to normal weight. When the long‐lived small lymphocyte population of the donor was labeled with3H‐thymidine, the location, morphology and mitotic activity of labeled cells was followed by radioautography. These cells were most frequently observed in the mid‐ and deep cortex and the medullary cords of the host node. Very few labeled blast cells were observed in sections or smears and radioautographs of chromosome spreads confirmed the infrequency of donor long‐lived small lymphocyte transformation and proliferation. Of the proliferating cells in the host node at the peak of the response, 60–85% were of host origin. These observations and others are discussed, and it is proposed that the host short‐lived small lymphocyte accounts for the majority of mitotic cells in the node at the peak of

ISSN:0003-276X    

DOI:10.1002/ar.1091790103

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

年代:1974

数据来源: WILEY

摘要:

AbstractIn an effort to elucidate various aspects involving the initiation of development, the morphogenesis of the spontaneously activated egg of the golden hamster was examined at the light and electron microscopic levels of observation. Spontaneous activation of the unfertilized hamster egg occurs upon prolonged incubation within the oviduct, i.e., aging in vivo, and may include the formation of the second polar body and the development of one or several pronuclei. In many instances the activated egg resembles the inseminated ovum at the pronuclear stage of fertilization. Occasionally the activated egg will divide and yields a structure which is morphologically similar to the two‐cell stage. Development beyond the two‐cell stage was not observed. Even though a number of events exhibited by the aging hamster egg mimic those of the fertilized, many are indicative of cellular degeneration. Such processes include, for example, the aggregation of organelles into fairly homogeneous clusters, the budding of portions of the cortex of the egg containing cortical granules into the perivitelline space, the accumulation of vesicles within the ooplasm and the structural modification of microvilli. All activated eggs, at every period investigated (6 to 66 hours post‐ovulation), contained cortical gra

ISSN:0003-276X    

DOI:10.1002/ar.1091790104

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

年代:1974

数据来源: WILEY

摘要:

AbstractEvidence for a direct neural projection from the retina to the hypothalamus in the golden hamster (Mesocricetus auratus) is presented. In 25 blinded animals degeneration was followed in sections prepared according to the Wiitanen ('69) silver impregnation method. Degenerative axons were found in the optic tract, chiasm, and nerve, terminating in the lateral geniculate body and superior colliculus. A large collateral bundle of degenerating axons was observed curving medially and dorsally to enter the hypothalamus at the level of the mamillary body. This bundle turned diffusely rostrally and terminated on neurons in the ventromedial nucleus of the hypothalamus.It is proposed that two alternate pathways exist for the effect of photoperiodicity on the reproductive cycle in the hamster, one involving the pineal gland directly and the hypothalamus indirectly, and the other a direct retino‐hypothalamic projectio

ISSN:0003-276X    

DOI:10.1002/ar.1091790105

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

年代:1974

数据来源: WILEY

摘要:

AbstractStudy of the caudal cochlear nucleus of the cat confirms the cochlear origin of synaptic terminals, identified in correlated rapid Golgi and electron microscopic preparations of the octopus cell area (OCA) and the dorsal cochlear nucleus (DCN) in normal cats. Type 1 and type 2 endings on octopus cell somas and basal dendrites, as well as type 1 and type 1a endings of the outer DCN, degenerate following complete ipsilateral cochlear ablations and short survival periods (12, 24, 48, 96 hours). Two distinct patterns of synaptic degeneration occur after short survival times; “dense degeneration” occurs in type 1 endings on octopus cells and several endings of the DCN. Dense terminals that contain tightly packed, but intact vesicles, occur most frequently after a 48‐hour survival period. A second type of degeneration, called “flocculent degeneration” occurs in type 1 and type 2 endings of the OCA and in type 1 and type 1a DCN terminals. Between 12 and 48 hours after ablation, the flocculent degeneration involves a continuous breakdown of organelles. Evidence for transneuronal degeneration of octopus cells and DCN granule cells is

ISSN:0003-276X    

DOI:10.1002/ar.1091790106

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

年代:1974

数据来源: WILEY

摘要:

AbstractThe objective was to study the fate of specific secretory cell types of the rat hypophysis when grown in primary monolayer cultures for periods ranging up to 32 days. The cells were identified immunohistochemically using peroxidase‐labeled antibody. Early in the culture period TSH‐cells were scarce and by 12 days they could no longer be identified. In most cultures LH‐cells were well stained and common for eight to 12 days, after which they underwent involution. Growth hormone cells were a prominent feature up to six days but by 12 days they were declining in number, size, and stainability; in contrast, prolactin cells proliferated and were large and intensely stained throughout the period of study, ultimately becoming the dominant secretory cell type. Corticotropic cells also continued throughout the period of study without regression. Thus drastic shifts occur with time in the relative proportions of cell types in monolayer cultures of rat pituitary

ISSN:0003-276X    

DOI:10.1002/ar.1091790107

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

年代:1974

数据来源: WILEY

摘要:

AbstractWhole‐body autoradiograms were prepared from intact and hypophysectomized (Hypox) rats after receiving125I‐HGH iv. In addition, some hypox rats received unlabeled HGH or ACTH six minutes before receiving the125I‐HGH. Hypox rats had greater concentrations of radioactive material in the renal cortex, adrenal cortex, liver and submandibular gland than was present in blood. Pretreatment with ACTH increased the radioactive material in the inner zones of the adrenal cortex; liver and renal cortex contained more radioactive material than blood; and the submandibular gland contained an amount equal to that in blood. Pretreatment with unlabeled HGH greatly suppressed uptake of radioactivity in liver and adrenal cortex and slightly increased the uptake in the renal cortex. Radioactivity could not be detected in the renal medulla or urine of any of the rats. No concentration of radioactive material greater than that seen in blood was present in any other organ or tissue in any of the groups. In the intact rats, the kidney and the adrenal cortex had the greatest concentrations of radioactivity, while the concentration in the liver was equal to that in blood. Autoradiograms were also prepared from sections from untreated hypox rats that were dipped in125I‐HGH solutions. These confirmed the presence of binding sites in the adrenal cortex and liver for125I‐HGH. No binding of radioactive material was seen in t

ISSN:0003-276X    

DOI:10.1002/ar.1091790108

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

年代:1974

数据来源: WILEY

摘要:

AbstractDistribution of mitotic nuclei in the biceps brachii of five day old mice has been studied after subcutaneous injection of 1μCi/gm body weight3H‐thymidine. Serial transverse sections at 5μm thickness were cut and the number of labeled nuclei per hundred fibers were determined on every fortieth section starting from the proximal end of the muscle.The proximal region of the muscle has significantly more labeled nuclei than either the belly region (P<0.005) or the distal region (P<0.001) of the muscle. The distal region of the muscle and the belly of the muscle did not differ significantly.Thus, most of the fiber elongation seems to take place at the proximal region of the muscle. As far as the transverse growth is concerned it appears that either every fiber at this stage is increasing in diameter or else the fibers which are undergoing an increase in diameter are randomly distributed throughout the body of the muscle, as no significant differences have been found in the percentage labeled nuclei in the four transverse areas of the muscle in the belly reg

ISSN:0003-276X    

DOI:10.1002/ar.1091790109

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

年代:1974

数据来源: WILEY

摘要:

AbstractThe course of reinnervation and the effects of denervation and immobilization on muscle development were examined during the regeneration of minced muscle in anurans. Reinnervation occurs in the second week, at the time of myotube formation and differentiation. At the end of thirty days, nerves are plentiful and extensively distributed within the regenerating muscle. Cholinesterase activity within the regenerated muscle cannot be demonstrated at this time. Denervated regenerates develop normally during the first two weeks, but, thereafter, the young muscle fibers exhibit signs of degeneration and retarded growth. Denervated regenerates become fibrotic and contain few muscle fibers at the end of four weeks. Regenerates from muscles denervated prior to mincing show an accelerated appearance of presumptive myoblasts in the first week, but despite this precocious development, these denervated regenerates become regressive. On the other hand, the effect of disuse on muscle regeneration is not detrimental; the fibers of reinnervated but immobilized regenerates develop normally and do not become degenerative. These results suggest that nerves are unnecessary for the early myogenic processes of proliferation and fusion, but are essential to later stages of growth, maturation and maintenance of the regenerated muscle fibers.

ISSN:0003-276X    

DOI:10.1002/ar.1091790110

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

年代:1974

数据来源: WILEY

摘要:

AbstractHypertrophic scar, mature scar, normal skin and granulation tissue were studied by transmission (TEM) and scanning (SEM) electron microscopy for characteristics and differences in fine structure, especially the collagen filaments and their physical association with each other and with interstitial components of the ground matrix.The shape of the collagen filaments is irregular and angular in granulation tissue, irregular to ovoid in hypertrophic scar, ovoid to round in mature scar, and round in normal skin. The mean diameter of the collagen filaments measures approximately 440 Å in granulation tissue, 600 Å in hypertrophic scar, 1000 Å in mature scar, and 1050 Å in normal skin.Interstitial filaments are prominent in hypertrophic scar by TEM. In nodular areas where collagen is examined in cross section the interstitial filaments often appear to interconnect long chains of collagen filaments. The interstitial filaments are not observed by SEM. Rather, by this method of observation, the demis of hypertrophic scar is seen as a homogeneous matrix, and individual collagen filaments are not observed.It is suggested that the hypertrophic scar is characterized by an unusually firm intercollagen binding by interstitial filaments, which are probably protein‐polysaccharides of the ground matrix. This relationship could account for the clinical quality of extreme hardness of the scar, and might also suggest an aberration important in the etiology of the

ISSN:0003-276X    

DOI:10.1002/ar.1091790111

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

年代:1974

数据来源: WILEY