ISSN:0003-276X    

DOI:10.1002/ar.1091800102

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

年代:1974

数据来源: WILEY

摘要:

AbstractMuscles of the perineal region were dissected in 20 cats. Levator ani muscle was composed of two parts: iliocaudalis and puboischiocaudalis; both parts inserted entirely on caudal vertebrae, as did the coccygeus muscle. A well developed band of smooth muscle, the pars analis of retractor penis (clitoridis), inserted on the anal canal to retract the anus. The external anal sphincter had pars caudalis and pars cranialis divisions, the latter covered paired anal sacs. In addition, a distinct sphincter encircled each anal sac duct. In the male, levator scroti muscle originated from external anal sphincter. There was no continuity between external anal sphincter and bulbospongiosus muscles. Cremaster muscles were absent in the cat. In the female, pars cranialis of external anal sphincter gave origin to the constrictor vestibuli muscle, and pars caudalis to constrictor vulvae muscle. Bulboglandularis muscles were present in both sexes. Urethralis, ischiourethralis, and ischiocavernosus muscles in the cat were similar to other quadripeds.

ISSN:0003-276X    

DOI:10.1002/ar.1091800103

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

年代:1974

数据来源: WILEY

摘要:

AbstractInnervation to muscles of the feline perineum was examined by gross dissection of the sacral nerve plexus and quantitation of efferent and afferent myelinated fibers in selected nerves derived from the plexus. In addition, distribution of muscle fiber sizes and muscle spindle content were determined for muscles innervated by the nerves studied.Efferent myelinated fiber populations were bimodal in nerves innervating muscles with many spindles and unimodal in nerves innervating muscles in which few or no spindles were observed. Coccygeus and levator ani muscles had similar numbers of muscle spindles, but the spindles were different in the two muscles based on afferent innervation. In both coccygeous and external anal sphincter muscles, primary spindle endings must be associated with relatively small afferent nerve fibers. The pelvic urethra received more large myelinated afferent fibers than the penis. The three divisions of the external anal sphincter muscle had three distinct populations of muscle fibers, based on size distribution. The homologous bulbospongiosus and constrictor vulvae muscles had different populations of muscle fibers.

ISSN:0003-276X    

DOI:10.1002/ar.1091800104

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

年代:1974

数据来源: WILEY

摘要:

AbstractA glycoprotein coat is demonstrable on the free surface of both the blastocyst and uterine luminal epithelium of the mouse on day 4 and day 5 of normal pregnancy, and on day 7 of delayed implantation, using concanavalin A‐peroxidase and ruthenium red. The coats are apparently negatively charged, as shown by their binding with colloidal thorium dioxide. The cell coat on uterine epithelium is appreciably thicker than that on the blastocyst. The information currently available is sufficient to suggest that simplistic mechanisms such as change in charge or total thickness cannot be the sole basis of initial adhesion, but that some localized reduction of the uterine surface coat accompanies adhesion. However, considerably more information is necessary concerning the nature of the surface coats before a more comprehensive understanding of the role of adhesion in implantation can be achieve

ISSN:0003-276X    

DOI:10.1002/ar.1091800105

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

年代:1974

数据来源: WILEY

摘要:

AbstractThree groups of mice were standardized to a light‐dark cycle with light from 0600 to 1800. One group was fedad lib; but the other two had access to food for only four hours a day, one during the first part of the light phase and the other beginning at its middle. Two other groups were subjected to a reversed light‐dark cycle (light from 1800 to 0600); one of these had access to food for four hours during the first part of the dark phase and the other for four hours beginning at its middle. All the mice previously had been adjusted gradually over a three‐week period to these feeding schedules, and then they were maintained on the precise routine described for an additional two weeks. After standardization was completed, subgroups of mice were killed at three‐hour intervals over a single 24‐hour period. Corneas were removed and prepared, and the mitotic index in the epithelium was evaluated.In all five groups a high‐amplitude circadian rhythm was found for the mitotic index, but in all cases this rhythm remained synchronized to the light‐dark cycle; only small changes in the phasing of the rhythm resulted from the restricted feeding. These results are contrary to what has been found for a number of other rhythmic variables which do synchronize to such feeding schedules.The findings dispel the misconception that all body functions react in the same fashion to different synchronizors and emphasize that one must not generalize about the effects of feedin

ISSN:0003-276X    

DOI:10.1002/ar.1091800106

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

年代:1974

数据来源: WILEY

摘要:

AbstractIt has long been known that in certain mammalian species the masseter muscle is a fast‐twitch muscle in spite of its red colour. We have investigated the histochemical fiber composition of this muscle in the rabbit and in different species of rodents. In the mouse, rat and guinea pig the masseter is uniformly composed of fibers displaying alkali‐stable and acid‐labile myosin ATPase activity like most fibers in fast‐twitch hindleg muscles and moderate to high succinate dehydrogenase activity. The homogeneity of the histochemical profile with respect to myosin ATPase activity makes this muscle especially suitable for correlated physiological, biochemical and ultrastructural studies. The rabbit masseter has a basically similar though relatively heterogeneous fiber composition with atypical histochemical properties. A sizable population of fibers in this muscle exhibit high levels of both alkali‐stable and acid‐stable myosin ATPase activity. Mitochondrial α‐glycerophosphate dehydrogenase activity, which reflects the glycolytic capacity of skeletal muscle fibers, varies in the masseter of different species in a way which cannot be exactly predicted on the basis of the reactions for myosin ATPase and succinate

ISSN:0003-276X    

DOI:10.1002/ar.1091800107

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

年代:1974

数据来源: WILEY

摘要:

AbstractCombined morphometric and autoradiographic methods were used to analyze the postnatal growth of rat lung from 1–21 days after birth. Each cell population had distinct growth patterns with an increase in the number of fibroblasts and capillary endothelial cells largely determining the increase in interstitial volume and capillary surface, respectively. The height of proliferation activity in mesodermally‐derived cells was concurrent with the outgrowth of secondary alveolar septa (between days 4 and 13). Analysis of the location of labeled cells on day 7 showed that the higher labeling index on septal crests could be ascribed to the proliferative activity of fibroblasts and endothelial cells.Within the alveolar epithelium only the type II alveolar cells had a detectable labeling index. Over the first week, the number of type I epithelial cells steadily increased while the number of type II cells remained constant. Subsequently the number of type II cells increased rapidly, reached a peak on day 13 and then decreased, whereas type I cells continued to increase in number. These facts led us to consider that type II epithelial cells may represent the stem cell population of alveolar epithelium. The height of proliferative activity of type II cells on day 7 coincided with the outgrowth of septal crests and was followed by the steepest increase in number of type I and II cells.Between the 10th and 21st day labeling indices rapidly declined, cell production became undetectable after day 13. Increase in alveolar and capillary surface area however continued, resulting in a thinning of the interstitial layer and of the epithelial and endothelial she

ISSN:0003-276X    

DOI:10.1002/ar.1091800108

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

年代:1974

数据来源: WILEY

摘要:

AbstractIn order to investigate the postnatal growth of the gas exchange apparatus, the lungs of rats aged 1, 4, 7, 10, 13, and 21 days were fixed by intra‐tracheal instillation of glutaraldehyde. The analysis and interpretation of the morphological changes observed by light and electron microscopy were based on the results of previous morphometric and autoradiographic studies performed on the same material.The newborn rat has no alveoli, but breathes with smooth walled air channels and saccules, which correspond to the prospective alveolar ducts and alveolar sacs, respectively. The bulk of alveoli are formed between days 4 and 13 by a rapid outgrowth of secondary septa from the primary septa present at birth. The arrangement of elastic fibers during this period suggests that these may play a role in septal outgrowth. Based on ultrastructural observations a model is described for the capillarisation of the secondary septa. Some evidence is given that alveoli may also be formed by outpouchings in the walls of terminal bronchioles.Primary and secondary septa have initially an immature appearance. They both show an apparently double capillary network, whereas the mature interalveolar septum is just wide enough to accommodate a single capillary. Possible mechanisms for this structural transformation which occurs within three weeks after birth are discusse

ISSN:0003-276X    

DOI:10.1002/ar.1091800109

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

年代:1974

数据来源: WILEY

摘要:

AbstractThe fathead minnow,Pimephales promelas(Rafinesque), has been laboratory bred and the early embryos staged and described. At 23°C the embryo requires 33 hours to reach the 13‐somite stage. This period of early embryonic development has been divided into 12 stages. The description of each of these stages is accompanied by photograp

ISSN:0003-276X    

DOI:10.1002/ar.1091800110

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

年代:1974

数据来源: WILEY

摘要:

AbstractThe surface topography of palatal shelves was examined by scanning electron microscopy prior to and during secondary palate formation in 72 therapeutically aborted human embryos and fetuses ranging in age from 37 days to 12 weeks (post‐fertilization). Alterations in epithelial surface appearance were observed in the prospective region of fusion prior to contact between the shelves. First seen as an elliptical area along the anterior portion of the presumptive medial edge, a zone of alteration spread progressively along the anterior four‐fifths of the medial edge prior to shelf contact, and continued along the posterior one‐fifth of the shelf as fusion proceeded. The altered zone eventually extended onto the oral surface in the middle of the shelf but was restricted to a narrow zone along the medial edge posteriorly. Initially characterized by elongation and “intertwining” of superficial cells, alterations later included cell death, desquamation and possible active migration of surface cells. The shelf epithelium subjacent to the zone of alteration exhibited increased irregularity in thickness and numerous “invaginations” into the underlying mesenchyme. These alterations are thought to reflect intrinsic changes within the shelf and may play a role in the fusion process. Evidence for surface remodeling following fusion was

ISSN:0003-276X    

DOI:10.1002/ar.1091800111

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

年代:1974

数据来源: WILEY