摘要:

AbstractHamsters were x‐irradiated at 300 R on 1, 7, 14, 21 or 30 days after birth and sacrificed at the age of 33 days.The body weight, testicular weight and the development of seminiferous tubules were severely affected by irradiation on day 1. The ovarian weight and the number of oocytes were more affected by irradiation on day 7 or 14. Effects of irradiation of immature hamsters on their growth and development of gonads appears to be permanent as irradiation of males on day 1 destroyed all their germ cells by day 33 and irradiation of females on day 7 caused their permanent sterility up to four months of ag

ISSN:0003-276X    

DOI:10.1002/ar.1091630301

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

年代:1969

数据来源: WILEY

摘要:

AbstractVarious parameters of ovarian activity were determined for the intact or hypophysectomized pregnant mouse, as a baseline to establish the nature of luteotropic hormones in this species.Seventeen per cent of White Swiss mice with a vaginal plug were not pregnant at subsequent stages of gestation. The greatest number of failures occurred between days 12 and 15 of pregnancy, coinciding with the temporary absence of antral follicles and regressive changes in the vaginal epithelium. This suggests that there is a period of transient hormonal imbalance before full placental function is established, which is responsible at this time for the peak in embryonic mortality.Two periods of luteal growth were apparent between days 1 and 4 and 10 to 14 of pregnancy. The first histologic evidence of luteal regression occurred at day 16, correlating with renewed squamous cell proliferation of the vaginal mucosa.There were no significant differences in the number of ova shed on day 1 of pregnancy (11.0 ∓ 0.5 ova) and the subsequent number of embryonic swellings at any stage. Gestation in intact pregnant mice lasted 18 days (n = 2) or 19 days (n = 36). The number of young counted late on day 1 post partum (9.1 ± 0.5) was significantly less than the number of embryonic swellings as a result of maternal cannibalism.Hypophysectomy on day 1 of pregnancy led to rapid histologic degeneration of the corpus luteum. In this feature, the mouse resembled the hamster rather than the rat. Day 10 of pregnancy represented the earliest time at which, at least in some animals the pituitary could be removed and pregnancy continue. Following hypophysectomy from day 11 on, luteal activity, continuation of pregnancy, fetal and placental weight and vaginal histology were comparable to intact, pregnant mice. This is similar to the hypophysectomized rat in the latter half of pregnancy but differs from the situation in the hamster.On the basis of the present findings and results in the following paper, it appears likely that the mouse placenta, in addition to secreting a prolactin‐like hormone, also produces other gonadotro

ISSN:0003-276X    

DOI:10.1002/ar.1091630302

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

年代:1969

数据来源: WILEY

摘要:

AbstractPregnant mice were hypophysectomized on day 6 and injected subcutaneously with various hormones from days 6 to 9 to establish the minimal requirements for the maintenance of functional corpora lutea. Luteal activity was assessed by the maintenance of pregnancy, weight of embryonic swellings, mean diameter and morphology of corpora lutea, and vaginal histology.Treatment with 2 mg progesterone maintained pregnancy but not corpora lutea in three of five animals. However, the embryonic swellings were significantly (P<0.0005) smaller than those of pregnant control animals. Pregnancy was maintained in all animals when progesterone was combined with 1 μg of estrone. The weights of embryonic swellings and the degree of vaginal mucification in the combined steroid group were similar to those of intact control animals.Treatment with either ovine prolactin, bovine LH, ovine FSH or estrone failed to maintain corpora lutea or pregnancy. Combined injection of prolactin with LH or estrone did not maintain pregnancy or corpora lutea. On the other hand, treatment with 500 μg of prolactin and 200 μg of FSH maintained pregnancy in 12 of 14 animals. All of the aforementioned parameters of luteal activity were comparable to values in intact, control animals.The data indicate that luteal function in the mouse during the early post‐implantation period requires a luteotropic complex rather than a single hormone. Prolactin and FSH constitute the minimal luteotropic complex in the pregnant mouse. The luteotropic activity of FSH was not due to its contamination with LH and the effect of FSH was apparently not mediated through estrogen secretion, since pregnancy was not maintained by prolactin and est

ISSN:0003-276X    

DOI:10.1002/ar.1091630303

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

年代:1969

数据来源: WILEY

摘要:

AbstractIn this experiment actinomycin D was used to explore the action of the wound epidermis on underlying tissues during limb regeneration. In axolotl forelimbs the skin was removed from the elbow to the shoulder. Skin from the right limbs was soaked for three hours in actinomycin D (5.0 or 10.0 μg/ml 0.6% NaCl). For controls, skin from left limbs was soaked in 0.6% NaCl for the same period of time. Each piece of skin was orthotopically replanted, and both limbs were amputated through the treated skin, proximal to the elbow. After an initial healing period, the control limbs regenerated normally. Except for a slightly paler color, limbs bearing actinomycin‐treated skin were indistinguishable from the controls, both grossly and histologically, during the first week following amputation. While the control limbs formed early blastemas, no grossly visible evidence of regeneration was apparent in the experimental limbs, but histologically some dedifferentiation was occurring. Normally three to four digits were seen in the control regenerates before blastemas appeared on the experimental limbs. By 35–40 days blastemas had appeared on most experimental limbs. These developed very rapidly, and within a short time many of them had attained levels of development close to the controls. Actinomycin D temporarily suppresses formation of the apical epidermal cap and the subsequent aggregation of dedifferentiated cells into a blastema. When the effect wears off, an apical cap forms and the dedifferentiated cells quickly organize into a blastema and begin to different

ISSN:0003-276X    

DOI:10.1002/ar.1091630304

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

年代:1969

数据来源: WILEY

摘要:

AbstractDeveloping myotubes in skeletal muscle tissue from the limbs of larval newts have been examined with respect to the ultrastructure and sequence of events accompanying myofibril formation. A population of filaments having a diameter of 100 Å is found to occur throughout and beyond the period of myofibrillogenesis. This population is in addition to developing actin and myosin filaments and probably does not contribute directly to myofibril formation. Rather it may represent a cytoskeletal network which ultimately becomes principally disposed around and at right angles to older myofibrils at the level of their Z‐bands.Assembly of thick and thin filaments into myofibrils seems to occur, in this muscle, predominantly near the periphery of the cell with registration of these components into A‐, I‐, and Z‐bands being accomplished as they assume progressively more internal locations. Z‐bands appear to develop by coalescence of Z‐bodies which in turn are earlier related to skeins of fine filamentous material which commonly occupy the most peripheral cytoplasm of these and other mesenchymally derived cells. Fine structural details of these skeins, Z‐bodies, and Z‐bands have been analyzed with regard to the several prevailing concepts of Z‐band architecture. An hypothetical sequence for myofibril formation and Z‐band differentiation is presented which takes into account several observations and relates them to the looping filament configuration previously proposed for mat

ISSN:0003-276X    

DOI:10.1002/ar.1091630305

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

年代:1969

数据来源: WILEY

摘要:

AbstractThe morphology of differentiating heterophils and eosinophils of the slender salamander,Batrachoseps attenuatus, was studied with electron microscopy. Enzymes of the granules of both cell types appear to arise from the Golgi cisternae. An agranular stem cell was not observed and the least differentiated cell type encountered was an “early” promyelocyte having small granules which are morphologically distinct from mature granules of either the heterophil or eosinophil series. Heterophil myelocytes and later stages contain only one population of granule which is fibrous in content. Eosinophils likewise possess but one type of granule; the granules are larger than those of heterophils, have a homogeneous content, and lack the crystallin core so characteristic of mammalian eosinoph

ISSN:0003-276X    

DOI:10.1002/ar.1091630306

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

年代:1969

数据来源: WILEY

摘要:

AbstractAnatomists and gynecologists have debated the existence of a rectovaginal septum in the human female. In this investigation the connective tissue between the vagina and rectum has been reexamined by both dissection and light microscopy in four specimen types. Specimens studied and compared totaled 143 and represent an age range of from eight fetal weeks to 100 years. Included were specimens from patients with different degrees of parity and both normal and abnormal pelvic visceral support.It has been shown that a definite rectovaginal septum exists in the human female and it is probably the homologue of the male rectovesical septum. The septum is well formed by the fourteenth fetal week and consists of a thin vertical sheet of dense connective tissue which is translucent in the fresh state. In the coronal plane the septum parallels the sacral curvature. It also curves posterolaterally to become fused with the parietal endopelvic fascia. The septum extends inferiorly from the rectouterine peritoneal pouch to the perineal body. It is usually adherent to the posterior aspect of the vaginal connective tissue, capsule. This adherence, together with the difficulty in identifying it histologically may explain why the existence of the rectovaginal septum has been denied.

ISSN:0003-276X    

DOI:10.1002/ar.1091630307

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

年代:1969

数据来源: WILEY

摘要:

AbstractThe heads of three‐day old rats were irradiated with a single dose of 200 r x‐ray and the animals were killed afterwards at intervals ranging from ten minutes to five days. Necrosis in the external granular layer of the cerebellum was evident by the fourth hour and the pyknotic cells increased in number up to 12 hours after irradiation. Between 24 to 48 hours all the pyknotic cells disappeared and the width of the layer was drastically reduced. By the third day after irradiation the external granular layer began to increase in width, and by the fourth day it was indistinguishable from normal. In adults of this group the cerebellum appeared structurally normal. In another experiment the cerebellum of rats was exposed from birth onward to 200 r on five successive days. In the animals killed immediately or one day after the last radiation session the external granular layer was totally or subtotally eradicated. In the animals surviving for four days the external granular layer reappeared over many regions of the cerebellum, and by the sixth day after irradiation it was present over its entire surface. In the latter group in animals that survived to 30 and 90 days of age the cerebellum contained a large, though subnormal, population of granule cells, indicating that the reconstituted cells were able to differentiate. These results suggested that the proliferative matrix of the postnatally developing cerebellum may be endowed with regenerative capac

ISSN:0003-276X    

DOI:10.1002/ar.1091630308

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

年代:1969

数据来源: WILEY

摘要:

AbstractThis investigation was undertaken to examine the effects of aging on alkaline phosphomonoesterase (Alk Pase) activity in the adrenals of a highly inbred strain of C57BL/10 male mice. A total of 140 male mice were assigned to seven main groups and sacrificed at 1, 4, 8, 12, 16, 20 and 24 months of age for biochemical and morphologic evaluations of adrenal Alk Pase activity. The biochemical findings indicated that while aging may result in a decrease of serum and liver Alk Pase activity, enzyme activity in the adrenals of male mice increases to a maximum level at approximately eight months of age and subsequently decreases at each successive age level. The histochemical findings revealed that the highest concentrations of enzyme activity occurred in the fascicular and reticular zones of sexually mature male mice. There were no major variations in zonal distribution with advancing age. Electron microscopy showed Alk Pase activity along membranes of cortical cells and within the subendothelial space.The progressive increase in Alk Pase enzyme activity up to eight months of age, and the subsequent fall in activity during senescence as well as its absence in the adrenals of female mice provides further support for a role of androgen in mobilizing cortical alkaline phosphomonoesterase activity.

ISSN:0003-276X    

DOI:10.1002/ar.1091630309

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

年代:1969

数据来源: WILEY