摘要:

AbstractOvaries obtained from the tadpole,Rana pipiens, and examined with the electron microscope revealed that many of the developing germ cells were joined together by intercellular bridges. All connections exhibited electron‐dense material on the inner surface of the plasma membrane, thus demonstrating the same basic structure as intercellular bridges described in other species. However, the presence of a sleeve‐like subsurface cistern beneath the dense border in the tadpole produces a morphologically more complex connection. A variety of cytoplasmic organelles, including mitochondria and elements of the endoplasmic reticulum, were seen within the confines of these bridges. Possible functions of intercellular bridges are discussed and it is suggested that certain developing germ cells function as nurse cells like those described in some invertebra

ISSN:0003-276X    

DOI:10.1002/ar.1091670102

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

年代:1970

数据来源: WILEY

摘要:

AbstractDifferences in succinate dehydrogenase and cytochrome oxidase activity and also in the Q o 2for a medium containing pyruvate, glutamate, fumarate and glucose (equimolar) were found using histochemical and manometrical methods, when muscle cells of the atria and the ventricles in the guinea pig heart were compared. Most of the activity values were higher in the ventricles than in the atria. According to cytomorphometric measurements, these differences can be explained by differences in the mitochondrial volume (per unit volume of cytoplasm) rather than by a different ultrastructural organization of the individual mitochondria, since they show the same stereological organization in both the atria and the ventricles. The reduced mitochondrial volume in the atria results in a lower density of “oxidative” (i.e., inner mitochondrial) membranes per unit volume of cy

ISSN:0003-276X    

DOI:10.1002/ar.1091670103

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

年代:1970

数据来源: WILEY

摘要:

AbstractVirgin female Sprague‐Dawley rats were mated, and after the appearance of vaginal plugs were placed in individual cages. The animals were sacrificed at different intervals from the second day of gestation until delivery. Breast tissue was studied with the light and electron microscope.The study suggests that breast tissue undergoes changes as early as four days after fertilization and continues throughout pregnancy. The changes start with accumulation of many ribosomes and polysomes within the epithelial cell cytoplasm. Lipid droplets appear early and increase in number as pregnancy advances. Two types of proteinaceous particles appear within the cytoplasm on the seventh day of gestation, and are totally secreted into the lumina before parturition. The particles are believed to play a role in colustrum composition. The Golgi apparatus plays no role in the formation of the proteinaceous particles. The particles are formed in relation to rough surfaced endoplasmic reticulum.The changes seen are limited to the ductular epithelium and are not seen in the large ducts. In animals treated with colchicine, mitoses are seen in the ductular epithelium very early in pregnancy and continue throughout the gestation perio

ISSN:0003-276X    

DOI:10.1002/ar.1091670104

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

年代:1970

数据来源: WILEY

摘要:

AbstractFemale Mongolian gerbils were x‐irradiated at various doses from 200r to 1200r on day 2 (fertilized eggs at 2‐cell stage) or day 9 (embryos at the early primitive streak stage) after mating and examined on day 18. No significant differences in numbers of corpora lutea were observed between controls and females irradiated at 200–800r on day 2 or day 9, although irradiation at 1200r on day 2 caused regression of all corpora lutea. Preimplantation loss as determined by the proportion of eggs that failed to implant in the pregnant females, was significantly increased only in the females irradiated at 1200r on day 2 (100% loss) as compared with control animals. The mean numbers of fetuses were significantly reduced in the females irradiated on day 2 at 400r (3.00 ± .71) and at 800r (1.2 ± .37), or on day 9 at 400r (3.0 ± 1.14) or at 800r (0) as compared with controls (5.4 ± .51). The embryonic loss after but not before implantation was significantly increased in all irradiated animals except those irradiated at 200r on day 9. When mated females irradiated at 400r or 800r on day 2 were examined on day 12, 15 or 16 of pregnancy, the mean diameter of implantation sites was significantly smaller in the females irradiated at 800r on day 2 (5.4 ± 0.53 mm) than those in the control females (9.3 ± 0.17 mm). No gross abnormalities of fetuses were observed in the control animals, only two abnormal out of 21 fetuses were found in females irradiated on day 2, but various abnormalities, such as retarded development, cleft palate, spina bifida, acephaly or amorphous fetuses were observed in 20 out of 45 fetuses from females irradiated at 200–400r on day 9. Histological examination of ovaries revealed that all pregnant females had fully developed corpora lutea while the ovaries of females without implantation sites following irradiation contained regressing corpora lutea, and in some cases newly formed corpora lutea. The number and morphology of chromosomes of embryos from females irradiated at 400r or 800r were examined, but no differences were found as compared with embryos of control animals.It appears that whereas x‐irradiation of the 2‐cell gerbil eggs increased the mortality of implanted embryos, irradiation of the early primitive streak stage caused embryonic death as well as developmental abnormalities. Chromosomal abnormalities of fetuses however

ISSN:0003-276X    

DOI:10.1002/ar.1091670105

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

年代:1970

数据来源: WILEY

摘要:

AbstractThe age‐related response of the ventricular capillary bed to enhanced work loads was investigated in male albino rats. During the 12‐week experimental period young, adult and old animals were trained on a motor‐driven treadmill. Resting bradycardia was found to occur after 8–12 weeks of training. Demonstration of the ventricular capillary bed was accomplished by injecting Pelikan biological ink retrograde into the ascending aorta of a beating heart. Capillary/muscle fiber ratios were slightly (6.5–9.5% ), but significantly, increased in all trained groups. The number of capillaries/mm2decreased with age but was higher in trained animals. Thus while aging is associated with a decrease in the concentration of ventricular capillaries, chronic exercise provides some mechanism which enhances the extent of the capi

ISSN:0003-276X    

DOI:10.1002/ar.1091670106

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

年代:1970

数据来源: WILEY

摘要:

AbstractThe manner in which the parotid gland forms around the related facial nerve branches was studied with the aid of reconstructions in 15 human embryos and fetuses 18 to 80 mm, crown‐rump length, 7+ to 13.5 weeks (w), menstrual age. Peripheral branches of the nerve terminate in the cervicomandibular region at 18 mm (7+w), when the unbranched parotid bud is farther rostral. By 22 mm (8w), a small nerve branch approaches the buccal region superficial to the bud that extends toward the preauricular region. At 26 mm (8.5w), several nerve branches course superficial to the parotid primordium which has first order ductules and is adjacent to the masseter muscle. Second order ductules form quickly (27 mm, 8.5w) as the primordium approaches the superficial aspect of the lower buccal, marginal mandibular and cervical nerve branches. The primordium enters the parotid space by 32 mm (9w) as third order ductules develop. At 37 mm (10w), it has fourth order ductules and the buccal nerve branches are superficial to the main duct. Nerve branches of the temporofacial ramus (temporal, zygomatic and upper buccal) occupy a superficial position in the primordium whereas branches of the cervicofacial ramus (lower buccal, marginal mandibular and cervical) are deeper. A similar arrangement is evident at 56–80 mm (11.5–13.5w) when the complex primordium has connections with its superficial and deep portions between many nerve bra

ISSN:0003-276X    

DOI:10.1002/ar.1091670107

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

年代:1970

数据来源: WILEY

摘要:

AbstractFour rabbit skeletons were completely analyzed for marrow contents by means of a volumetric technique developed previously in a study of the dog skeleton (Gong and Arnold, 1965). The distribution of the marrow in various skeletal areas as well as the relative contents of the three marrow components (water, fat and non‐fatty organic fraction) were determined.It was found that more than two‐thirds of the rabbit marrow was located in the various flat bones and one‐third in the long bones. In spite of this, almost half of the skeletal marrow fat was located in the long bones. The nonfatty organic fraction of the marrow in the long bones, on the other hand, constituted only one‐sixth of that found in the whole animal skeletal marrow. In terms of total marrow, about 51% of the rabbit skeletal volume was marrow. Based on the concept that fat‐free marrow is a more adequate index of active marrow than the red marrow (Gong and Arnold, 1965), the distribution of the various centers of marrow activity was described and

ISSN:0003-276X    

DOI:10.1002/ar.1091670108

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

年代:1970

数据来源: WILEY

摘要:

AbstractAutonomic innervation of rabbit salivary glands was demonstrated by modifications of the methods of Falck for catecholamines and Koelle for the localization of cholinesterase activity. To avoid and diminish artifacts, tissues were rapidly frozen, cut in a cryostat, and freeze‐dried under vacuum. Catecholamine fluorescence and cholinesterase activity were found in the serous parotid and the mainly mucous submandibular gland, strongly indicating that both glands are innervated by sympathetic and parasympathetic fibers. In the parotid gland, the sympathetic ground plexus apparently forms a denser network than that seen in the submandibular gland. Catecholamine fluorescence, indicating sympathetic nerves, is found to be closely related to most acini, blood vessels of both glands, and some ducts of the submandibular gland. Cholinesterase activity, signaling the presence of parasympathetic fibers, was observed around many acini, ducts, and some blood vessels of both glands. A theory is presented that the autonomic innervation of salivary glands influences the state of intracellular colloids, water, and electrolytes during secretio

ISSN:0003-276X    

DOI:10.1002/ar.1091670109

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

年代:1970

数据来源: WILEY

摘要:

AbstractAnatomical age markers are established in the small Indian mongoose (Herpestes auropunctatus) for embyronic, fetal, nestling and juvenile stages. Embryos and fetuses excised from living pregnant females and placed on a time scale of 49 days, the known gestation period, indicate that implantation is at approximately eight to ten days after insemination and that the transition from embryo to fetus occurs at about 14 to 28 days. The sequence of stages grossly discernible in prenatal development is highly similar to that in other mammals. Age in laboratory‐reared pups was correlated with a regular sequence of tooth eruption and replacement. The full set of permanent teeth is present at the age of 22 weeks. M3was found in 2.8% of 142 adult skulls examined. Prominent reductions occur in the slope of the growth curve during early fetal stages, and at birth, weaning and independence from the mothe

ISSN:0003-276X    

DOI:10.1002/ar.1091670110

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

年代:1970

数据来源: WILEY

摘要:

AbstractThe development of the adrenergic innervation of the puppy kidney from birth to two months of age was studied with the fluorescence histochemical method of Falck and Hillarp in conjunction with chemical analyses for catechol‐amines in the cortex and medulla of the kidney. At birth adrenergic fibers were found entering the kidney with the renal arteries and following the arterial supply into the inner cortex. In this area the fibers were found in association with the interlobular arteries and afferent arterioles. Fibers were also seen in the neogenic zone of the cortex until the fourteenth day after birth when this area disappeared. From the fourteenth to fifty‐sixth day the adrenergic fibers were found extending to the interlobular arteries and afferent arterioles of the developing cortex. The levels of norepinephrine measured in the cortex during the first two months after birth reflected the increasing number of adrenergic nerves. In the medulla vasa recta were present at birth; norepinephrine and fluorescent fibers, however, were not found until 21 days. At this time nerves were found emerging in bundles from the arcuate connective tissue sheath and joining the vasa recta in the outer medulla. At subsequent ages the number of fibers in each bundle and the norepinephrine levels increa

ISSN:0003-276X    

DOI:10.1002/ar.1091670111

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

年代:1970

数据来源: WILEY