摘要:

AbstractMyoid cells of the thymus of hibernating frogs were examined by electron microscopy. This cell type is represented by immature, fully‐developed and degenerating cell forms. The immature forms are mainly located at the surface, whereas the developed ones are found in the inside of the thymus. A peculiar type of immature cell containing no thick filaments, but possessing a rich sarcoplasmic reticulum among the thin filaments is described. The developed myoid cells have a myofibrillar apparatus showing regular cross‐striations. The myofibrils are arranged in concentric layers around the nucleus. The proposed role and origin of myoid cells and their probable connection with myasthenia gravis are discus

ISSN:0003-276X    

DOI:10.1002/ar.1091650302

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

年代:1969

数据来源: WILEY

摘要:

AbstractYoung and senescent female hamsters were sacrificed on days 8, 10, 12, 14 and 15 of pregnancy, and the number of viable and resorbing conceptuses was determined. The ovulation rate for each group was also recorded. At each day, there was a reduction in the litter size in senescent animals as compared to the young, but the number of ovulations in each age group was equal. The results indicated that the litter size loss, in senescent hamsters, is not due to a reduction in the ovulation rate, but to a seven fold increase in preimplantation deaths and to a two fold increase in resorption.

ISSN:0003-276X    

DOI:10.1002/ar.1091650303

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

年代:1969

数据来源: WILEY

摘要:

AbstractOvaries from young and senescent hamsters were examined morphologically on days 8, 12 and 14 of pregnancy to determine if there were any differences between the two age groups. The senescent hamsters had fewer follicles present than the young on all days of gestation. The senescent females' corpora lutea experienced the greatest growth between days 8 to 12, whereas corpora lutea from young animals grew the most between days 12 and 14. Corpora lutea in senescent females did not grow at all between days 12 and 14. The lower number of follicles in senescent females was not due to the lower rate of implantation. Superovulation with PMS revealed that the senescent ovary was refractory.It was concluded that there are quantitative not qualitative differences between ovaries from young and senescent hamsters during pregnancy. The refractory ovary of senescent females could be contributing to pregnancy wastage in this species by secreting less progesterone.

ISSN:0003-276X    

DOI:10.1002/ar.1091650304

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

年代:1969

数据来源: WILEY

摘要:

AbstractThe growth changes in the cranial base of the rabbit between one and 20 weeks after birth have been investigated. The basicranial axis and its anterior extension completed some 50% of their growth during this period in contrast to the posterior extension which had completed 70% before one week. The sphenoethmoidal angle underwent no statistically significant changes despite a decrease in the spheno‐maxillary angle indicating that the face became disposed below rather than directly anterior to the braincase. The foramino‐basal angle decreased progressively during the period of investigation.The pattern of growth in the linear dimensions of the rabbit cranial base is essentially similar to that already established in man and subhuman primates. The angular changes, however, differ from those in primates where the spheno‐ethmoidal and foramino‐basal angles follow more closely the developmental patterns of the braincase and facial s

ISSN:0003-276X    

DOI:10.1002/ar.1091650305

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

年代:1969

数据来源: WILEY

摘要:

AbstractThe effect of antigenic stimulation with pertussis and sheep red blood cell antigens was studied in the rat popliteal lymph nodes. H3‐leucine was used to assess protein metabolism in the various cell types of the reactive lymph nodes following both primary and secondary stimulation with these antigens. Radioautographs of tissue smears were used to make quantitative and qualitative assessments of the extent of intracellular protein synthesis. In addition, changes in the cellular populations of various lymphoid cell lines were determined utilizing differential cell counts and total cells present in the reacting nodes. These data were used principally to assess the role of the lymphocytic cells in the ontogeny of the immune response.Large and medium lymphocytes responded to antigenic stimuli by increasing intracellular protein synthesis. This newly synthesized protein most likely reflected the requirements of large and medium lymphocytes for growth, division and the production of immunoglobulins. The small lymphocytes, as a group, showed only minimal changes in intracellular protein synthesis following antigenic stimulation.The responses by large and medium lymphocytes and plasma cells were qualitatively similar following primary and secondary stimuli. The differences in these responses appeared to be reflected by the number of cells involved and by the temporal sequence in which the cells appeare

ISSN:0003-276X    

DOI:10.1002/ar.1091650306

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

年代:1969

数据来源: WILEY

摘要:

AbstractFemale mice of a Swiss albino stock were fed a high‐fat, low‐protein, hypolipotropic diet which produces rapid cardiovascular lesions in this stock of mice. Half of the animals were killed after 45 days and the others were placed back on a diet of normal laboratory chow and killed after one, two and three weeks of refeeding.In animals killed after receiving the experimental diet for 45 days small, focal deposits of hyalin in media of large coronary arteries of the right ventricle was the major change.During the first week of recovery (fed a normal diet) the incidence and severity of arterial lesions increased and within individual hearts arteries of all sizes and in both atria and both ventricles were involved. Following hyalinization an acute arteritis developed that involved all layers of the arterial wall and extended into the perivascular space.After two and three weeks recovery the coronary arteries were characterized by a periarterial fibrosis and by a decrease or absence of the leucocytic reaction. A subendothelial hyperplasia of smooth muscle, arranged longitudinally, was accompanied by an increase in reticular and collagenous fibers. Circular smooth muscle in the media was also hyperplas

ISSN:0003-276X    

DOI:10.1002/ar.1091650307

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

年代:1969

数据来源: WILEY

摘要:

AbstractFemale mice of the Taconic Swiss stock were fed one of the three diets described below then injected subcutaneously with 0.035 cm3CCl4/100 gm body weight in a mineral oil solution. One group was fed an adequate commercial laboratory ration, then mice were killed 12, 24 and 48 hours after CCl4; another a cholinedeficient, high‐fat, low‐protein diet for 14 days, then injected with CCl4, and killed 12, 24 and 48 hours later; and another group, a choline‐supplemented (2 gm choline chloride/100 gm diet), high‐fat, low‐protein diet for 14 days, then injected with CCl4and killed 24 hours later.In the group fed the normal diet, the polyhalogen produced within 24 hours the expected centrolobular necrosis and glycogen depletion, involving one‐third to one‐half of the lobular areas. In fatty livers produced by feeding the choline‐deficient diet, necrosis at 24 hours post injection was limited in a majority of instances to a zone one or two cells thick immediately surrounding the central vein. Despite this decreased necrosis in fatty livers centrolobular glycogen depletion still involved one‐third to one‐half of lobules and there was an infiltration of inflammatory cells immediately adjacent to the central vein. The hepatic necrosis at 12 and 48 hours paralleled that in the normal dietary group.Feeding of the choline‐supplemented, high‐fat, low‐protein diet for two weeks produced an extremely limited parenchymal liposis. In such relatively non‐fatty livers CCl4produced hepatic necrosis comparable to that in mice receiving normal diets. The extent of protection from the necrogenic actions of CCl4was clearly associated with extensive intracytoplasmic li

ISSN:0003-276X    

DOI:10.1002/ar.1091650308

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

年代:1969

数据来源: WILEY

摘要:

AbstractAn electromyographic investigation of the activity of the paired genioglossus and geniohyoid muscles of twenty‐six human subjects during deglutition revealed a general pattern of muscular activity involving an initial build‐up, gradual summation, and tapering of electrical potentials during swallowing of both saliva and water. There is an observable difference in the pattern of swallowing of individuals within a group and among the individual swallows of a single subject. There are longer periods of electrical activity during a saliva swallow than during a water swallow. The type of bolus also seems to affect the pattern of activity in the individual muscles as well as the length of time that they are working. The geniohyoid muscles do not appear to begin their activity with the genioglossus muscles but rather lag behind and they do not appear to be active for as long. Both pairs of muscles appear to remain active during and after the time that the bolus has passed the area of the laryngopharynx. A period of electrical silence occurs prior to the characteristic burst of activity associated with a swallow. This appears to be the result of an active inhibit

ISSN:0003-276X    

DOI:10.1002/ar.1091650309

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

年代:1969

数据来源: WILEY

摘要:

AbstractA study was made of 174 eggs recovered from 58 guinea pigs killed between the first and sixth days after mating, and the cytological details from the stage of sperm penetration to the pre‐implantation blastocyst described. Eighty‐nine percent of the expected number of eggs were recovered, and 97% of these were fertilized. Embryonic development proceeded from pronuclear and 2‐cell eggs on day 1 to pre‐implantation blastocysts on day 6, the duration of each of the early cleavage stages being of approximately 24 hours. No progressive loss of embryos was found over this period, all the eggs recovered on days 4, 5 and 6 being regarded as developing normally. Passage of embryos from the Fallopian tubes to the uterus commenced on the afternoon of day 3, and the majority of embryos entered the uterus shortly after this time at the stage of 8‐ to 16‐cells. The tail of the fertilizing spermatozoon was detected in the cytoplasm of all eggs examined on day 1, in most of those examined on day 2, and frequently persisted up to the 8‐cell stage. Three dispermic eggs, each containing two distinct cytoplasmic sperm tails, were found: one of these was at the pronuclear stage, the other two being considered of 4‐ and 6‐cells respectively. Properties of adhesiveness were shown by blastocysts recovered shortly before implantation on day 6, but the characteristic “zona proce

ISSN:0003-276X    

DOI:10.1002/ar.1091650310

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

年代:1969

数据来源: WILEY

摘要:

AbstractThe placental membranes of the four‐eyed opossum were studied by light and electron microscopy. The individual fetuses in each uterus were surrounded by amnion, had allantoic sacs of approximately the same size as each fetus, and were situated in a common yolk sac cavity. The extent of the choriovitelline placenta was marked by a prominent sinus terminalis, and at this margin there was a region where the trophoblast cells penetrated folds of the endometrium. Elsewhere the choriovitelline placenta was closely applied to the uterine epithelium along most of its surface, but the microvilli of the two epithelia did not interdigitate. Numerous inclusion bodies were seen in the trophoblast of both the choriovitelline and bilaminar omphalopleure portions of the placenta, but the aggregates were larger in the latter. The endoderm cells of the choriovitelline placenta had extensive endoplasmic reticulum and numerous mitochondria, but did not have conspicuous absorption canaliculi.Placentation in the four‐eyed opossum appears to represent a progressive advance over that of the Virginia opossum both in confluence of the yolk sacs of the fetuses and in having a region of penetration of the maternal endometrium by trophobl

ISSN:0003-276X    

DOI:10.1002/ar.1091650311

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

年代:1969

数据来源: WILEY