摘要:

The development of the omental bursa (lesser sac) was studied in serial sections of hybrid mouse embryos of 9–11½ days. The anlage of the bursa is represented by several indentations on the right side of the mesenterium. Further growth and topographic alterations of the adjoining organs determine the definitive shape of the lesser sac. On the left side, the recessus pneumato-entericus is a transient structure which persists only until the 11th day of gestation. In humans, the anlage of the bursa is almost identical with its origin in mice. The bursa facilitates the separation from the digestive tract of several organs developing in the mesente

ISSN:1422-6405    

DOI:10.1159/000145564

出版商:S. Karger AG    

年代:1982

数据来源: Karger

摘要:

Coronary arteries and arterioles in the left and right ventricles from normal and hyperthyroid rats were examined histochemically to determine and to compare their metabolic activities. The test animals were made hyperthyroid by administration of desiccated thyroid for 8–10 weeks. Using histochemical techniques, selected enzymes and components of key metabolic pathways were examined. These pathways included an evaluation of aerobic (oxidative phosphorylation, Kreb’s cycle and respiratory chain) and anaerobic metabolic capacity, hexose-monophosphate shunt activity, amounts of deoxyribonucleic and ribonucleic acids present and activity of β-oxidation of fatty acids. Our results indicate that normal coronary arteriolar metabolism is predominantly aerobic. The findings also suggest a reduction in aerobic metabolism with an accompanying increase in anaerobic potential in the hyperthyroid coronary arterioles. Thus, during thyrotoxicosis, the coronary arterioles may partially shift from aerobic to anaerobic metabolism. Moreover, in both the normal and thyrotoxic rat heart, the coronary microvasculature appears quite stable with little cell proliferation. In contrast, both the control and hyperthyroid rat coronary arteries appear to utilize primarily anaerobic pathways, while the control and hyperthyroid myocardium seem highly dependent upon aerobic metabolism. The tremendous reduction in glucose-6-phosphate dehydrogenase activity in hyperthyroid, when compared to normal coronary arteries and some larger arterioles, implies a reduced capacity for nucleic acid and protein synthesis in the test ani

ISSN:1422-6405    

DOI:10.1159/000145565

出版商:S. Karger AG    

年代:1982

数据来源: Karger

摘要:

The development of digital joints of chick embryo paralyzed with dacamethonium bromide and of joints in chick embryo limb buds cultured on chorioallantoic membranes was studied. The digital joints of 45 paralyzed and 40 control embryos and the joints of 37 grafts and 30 control legs were examined histologically. Six preselected grafts were studied by electron microscope. Our results demonstrate that paralysis does not completely inhibit the early stages of joint clefting. In many paralyzed embryos, small clefts appeared in the periphery and occasionally in the central part of the interzone. Unlike in normal embryos, they rapidly disappeared, inducing fusions across the joints. Early, 2-day paralysis during a period of normal clefting inhibited irreversibly the development of the articular cavity that failed to appear after a cessation of the drug. Paralysis initiated in older embryos caused rapid regression and partial fibrous ankylosis of previously fully differentiated joints. Grafts from 4- to 6-day-old embryos usually failed to develop a full range of skeletal segments. Normal development of skeletal segments occurred in grafts from older donors. The articular cavity failed to develop in almost all grafts. Early cavitation accompanied by characteristic cell changes was found in a few joints. These cellular changes are suggestive of an intrisic mechanism of early cavitation, but joint motion is required for the full differentiation and maintenance of the joint cavity.

ISSN:1422-6405    

DOI:10.1159/000145566

出版商:S. Karger AG    

年代:1982

数据来源: Karger

摘要:

There is an account of the basic neuronal connectivities of the spinal cord with the Sherringtonian principles of divergence and convergence. Neurones act synaptically either as excitatory or as inhibitory, depending on the specific transmitter substances liberated. Inhibitory neurones usually act either in a feedback or a feedforward manner. Voluntary movement is considered in relation to the instructions delivered to the motor cortex in order to produce the discharges down the pyramidal tract that evoke the required movement. There is an account of the three lines of evidence which indicate that in voluntary movements the primary neural event arises in discharges of neurones of the supplementary motor area (SMA). There are three main circuits from the SMA that activate subroutines concerned in the preprogramming of movements: (1) SMA to the basal ganglia, thence to the thalamus with a collateral line through the substantia nigra, thence to the association cortex; (2) SMA to cerebellar hemisphere via the pontine nuclei, thence to the nucleus dentatus, to the thalamus, to the association cortex, and (3) SMA to association cortex both frontal and parietal. According to the SMA hypothesis the liaison brain for intention is located in the SMA, there being reciprocity of informational flow from the mental events of intention to the neuronal events in the SMA.

ISSN:1422-6405    

DOI:10.1159/000145567

出版商:S. Karger AG    

年代:1982

数据来源: Karger

摘要:

10 sheep were used for light microscopic studies to describe the distributions of the blood vessels, epithelium, and glands of the nasal cavity. The animals were killed following intramuscular injection of Rompun solution (xylazine hydrochloride). The heads were sawed and tissues were taken from the alar fold, respiratory, and olfactory regions. More vascularity was noticed in areas of the nasal cavity that were in direct contact with the airstream. Moreover, in the submucosa, the presence of arteriovenous anastomoses, collagen fibers, elastic fibers, thick-walled or cushion veins, and free smooth muscle cells was observed, gradually decreasing from the rostral to caudal regions. The tunica media of the arteries was very thin in the vestibular region and relatively thicker in the respiratory region. On the other hand, luminal diameters of the arteries were very small in the respiratory region and relatively larger in the vestibular region. In addition, a large number of intra-arterial bolsters was present in the respiratory region, but there were fewer in the olfactory region, and they occurred with still less frequency in the vestibular region.

ISSN:1422-6405    

DOI:10.1159/000145568

出版商:S. Karger AG    

年代:1982

数据来源: Karger

摘要:

The bilateral distribution of carotid body type I cells was investigated in 5 mongrel dogs and compared with the arrangement of type I cells in 3 beagles by serially sectioning the carotid bifurcation regions. The distribution of type I cells was not affected by the pedigree of the dogs. In both mongrel dogs and beagles type I cells were arranged in close proximity to the wall of the ascending pharyngeal artery within a division of connective tissue with defineable but irregular borders. Occasionally, type I cells were observed in relation to the occipital and external carotid arteries. This association of type I cells and connective tissue formed the principal mass of the carotid body. Caudally, and separate from the principal mass, isolated groups of periadventitial type I cells lay freely in the connective tissue adjacent to the internal and external carotid arteries in both mongrel dogs and beagles. Less commonly, and in mongrel dogs only, periadventitial type I cells were noted alongside the carotid bifurcation and the rostral end of the common carotid artery. Three-dimensional reconstructions of the distribution of carotid body type I cells and periadventitial type I cells from the left and right carotid bifurcation regions were made. In all specimens rostral-caudal dimensions of the distribution of carotid body type I cells and periadventitial type I cells were recorded and compared bilaterally.

ISSN:1422-6405    

DOI:10.1159/000145569

出版商:S. Karger AG    

年代:1982

数据来源: Karger

摘要:

The cellular composition of the human marrow was studied in thin sections of undecalcified bones of 24 fetuses aged from 11 to 22 weeks of gestation, embedded in methacrylate and stained by the Giemsa method. This procedure provides much better cellular detail than the decalcified bone sections embedded in paraffin used in previous studies. Hemopoiesis is already present at the 11th week of gestation in the long bones of the extremities. The cellularity of their marrow increases during the 4th month and is abundant in the months thereafter. Its composition is similar to that of adults but differs by the presence of a large number of stromal cells and by the absence of plasma cells and lymph follicles in the fetal marrow. Differential counts for blood-forming cells and stromal elements are given for the initial period of marrow development.

ISSN:1422-6405    

DOI:10.1159/000145570

出版商:S. Karger AG    

年代:1982

数据来源: Karger

ISSN:1422-6405    

DOI:10.1159/000145571

出版商:S. Karger AG    

年代:1982

数据来源: Karger

ISSN:1422-6405    

DOI:10.1159/000145572

出版商:S. Karger AG    

年代:1982

数据来源: Karger

ISSN:1422-6405    

DOI:10.1159/000145573

出版商:S. Karger AG    

年代:1982

数据来源: Karger