摘要:

The present report deals with the histo-enzymological mapping of adenosine triphosphatase and simple esterase in the diencephalon and mesencephalon of Uromastix hardwickii. The enzymatic make-up, in both cases, does not differ markedly in the various nuclei; few variations, of course, occur in some midbrain areas like pretectal nuclei. The latter are intensely positive for ATPase, while these nuclei are moderate to simple esterase. Nevertheless, one of the most interesting results pertaining to simple esterase activity is of a high order in the fiber tracts in comparison to ATPase. The other interesting feature relates to the fact that generally intensely positive nuclei, in ATPase preparations, are those which have extensive efferent fibres. The metabolic significance of high degree of ATPase activity vis-à-vis extensive efferent connections has been exhaustively discussed, besides the possible significance of the general data obtained

ISSN:1422-6405    

DOI:10.1159/000144624

出版商:S. Karger AG    

年代:1976

数据来源: Karger

摘要:

The development of the vascular patterns of the lumbosacral segments of the chick embryo spinal cord has been analyzed in normal as well as in experimental conditions, after complete removal of the hind limb primordium. The results indicate that in both conditions the development of the vascular network follows the time-space sequence of the cytoarchitectural modifications of the cord, supporting the view that the vascularization does not exert a morphogenetic influence.

ISSN:1422-6405    

DOI:10.1159/000144625

出版商:S. Karger AG    

年代:1976

数据来源: Karger

摘要:

We have studied the neuroectoderm of the chicken embryo, from the beginning of somitic segmentation up to the stage at which it has seven somites, i. e. the period covering the passage from the ‘neural canal’ into the ‘neural tube’. This paper was devoted mainly to the study of the ultrastructural cytodifferentiation which takes place during the stages in which the neural canal closes up, and at the level of the first area of contact between the ‘neural crests’ – roughly at the level of the third somite. We used eggs from a hen of the White Leghorn breed, incubated at 38 °C, from which we extracted chicken embryos after 24–30 h of incubation, corresponding to Hamburger-Hamilton’s stages 7, 8 and 9. Thus we were able to obtain several series of embryos with three, six and seven somites. The neural canal, or tube, at the level of the third somite, was fixed in glutaraldehyde at 6.25% for 30 min and postfixed in 1% osmium tetroxide for 2 h embedded in Araldite, and the sections were then stained with lead citrate. We observed that the vacuoles in the free edge of the neural canal gradually disappear as the canal closes up, while we gradually witness the appearance of the ‘closure apparatus’ (or the safety or occlusion apparatus) of what is beginning to form the ependymal epithelium, and the first rudimentary outlines of the cilia. All these changes begin to be observed at the seven-somite stage, i.e. when the neural canal is beginning to close up. The ‘closure apparatus’ consists of a number of intercellular joint complexes, of the ‘close-joint’ type, between which we observe a number of fine filaments, like a terminal velum’, or veil, which we call ‘interconnecting filaments’. In the ‘raphe’, whereby contact is established between the neural crests, we observe the initial stages of fusion between the vacuolated edges, with the plasmatic membrane of these cells forming very fine cytoplasmic ‘tongues’ which interdigitate with cells from the opposite neural crest and f

ISSN:1422-6405    

DOI:10.1159/000144626

出版商:S. Karger AG    

年代:1976

数据来源: Karger

摘要:

Histological preparations of thyroid, parathyroid and thymus glands of Herpestes edwardsi were examined for calcitonin cells. They reveal that (1) the thyroid calcitonin cells are oval, rounded and rarely elongated in shape; these cells and their nuclei are distinctly larger than those of the follicular cells and their nuclei; (2) calcitonin cells are unevenly distributed in the thyroid, with the result that certain portions of the thyroid are completely devoid of these cells; (3) on an average, calcitonin cells are in a ratio of 10–15 cells/100 follicular cells; (4) the parathyroid and thymus glands do not display calcitonin cells, and (5) the thyroid gland displays unusual follicles of two categories, (a) follicles with ciliated epithelial cells and (b) follicles with squamous epitheliu

ISSN:1422-6405    

DOI:10.1159/000144627

出版商:S. Karger AG    

年代:1976

数据来源: Karger

摘要:

Studies were carried out on the nuclear size of embryonic mouse brain monolayer cells at various cell densities. The variation in cell density resulted from different initial cell numbers. The nuclear area was measured area-analytically with the Quantimet, the determination of cell population was measured linear-analytically using the Digiscan. Nuclear size remains constant in a cell culture of 104 up to 8.3 × 104 cells ml, which corresponds to a cell density of about 25–160 cells/unit. A significant diminution in mean nuclear size of the cell nucleus occurs in the case of increased cell densities of 215 and 277 cells/unit, corresponding to a cell culture of 2.5 × 105 and 7.3 × 105 cells ml. This diminution may be connected with the accumulation of Gl cell nuclei in cultures with contact-dependent growth inhibi

ISSN:1422-6405    

DOI:10.1159/000144628

出版商:S. Karger AG    

年代:1976

数据来源: Karger

摘要:

Nucleo-cytoplasmic transfer rates of RNA were used as indices of protein-synthetic activity in mammalian supraoptic and paraventricular neurones. Normal, dehydrated and lactating rats were exposed, for varying periods of time, to tritiated uridine, and autoradiographs obtained from hypothalamic blocks. Grain count and cytometry enabled a cytoplasmic/nuclear ratio of grain densities to be obtained for each neurosecretory nucleus. Comparison of these ratios, as well as the regression slopes for their increase with time of exposure to the isotope, indicated the presence of a differential response between the supraoptic and paraventricular nuclei, with the former responding more to the stimulus of dehydration, and the latter to that of lactation. The observations substantiate the view that a partial division of labour exists between the two nuclei in the elaboration of each of the mammalian neurohypophysial octapeptides, vasopressin and oxytocin.

ISSN:1422-6405    

DOI:10.1159/000144629

出版商:S. Karger AG    

年代:1976

数据来源: Karger

摘要:

A correlation between the structure of the wall of the bone lacuna and the localization of the osteocyte within this lacuna was the object of investigation under light and electron microscopes. On the basis of the structural divergences detected, the author distinguished zones A and B in the osteocyte situated in the lacuna. Zone B is characterized by a parallel, compact system of collagen fibrils which form a characteristic ridge in the lacunar wall, a continuous demarcating line bordering this wall, the osteocyte cytoplasm in this part lying far from the lacuna wall and surrounding the nucleus with a narrow band, and the pericellular space which is wide here and containing a large number of mucopoly-saccharides. This picture may correspond to the area of temporary non-reactivity of the osteocyte. Zone A is characterized by a loosened and disordered system of collagen fibrils forming the lacunar wall. These fibrils being exposed in this place by nature, the demarcating line bordering the lacunar wall is broken in some places, the osteocyte cytoplasm is considerably concentrated around the nucleus and contains a large number of organelles. It also lies closer to the lacunar wall, which results in a decreased width of the pericellular space and a diminished mucopolysaccharide content in this part of the lacuna. Structural variations in the lacuna wall and its space (zones A and B) observed in the images obtained with a normal bone in the light and electron microscopes show their immediate dependence on the position of the osteocyte in the lacuna, which may be associated with the osteocyte activity. On the other hand, the occurrence of significant changes in a definite zone (zone A) of the lacuna only points to the oriented character of this activity.

ISSN:1422-6405    

DOI:10.1159/000144630

出版商:S. Karger AG    

年代:1976

数据来源: Karger

摘要:

Alkaline phosphatase activity was examined in the human tonsils in fetal life and after repeated attacks of acute tonsillitis and in quinsy. Gomori’s metal precipitate technique was used to demonstrate the phosphatase activity using four different substrates: sodium β-glycerophosphate and adenosine triphosphate at pH 9, riboflavin 5-phosphate at pH 9.2 and 5-monophosphoric acid at pH 8.3. (2) The phosphatase activity differs somewhat according to the phosphate ester used as a substrate illustrating an example of ‘substrate specificity’. (3) Alkaline phosphatase activity was increased in the case of both acute and chronic inflammation. This increase has been discussed in relation to such phenomena as transformation of lymphocytes into macrophages and antibody for

ISSN:1422-6405    

DOI:10.1159/000144631

出版商:S. Karger AG    

年代:1976

数据来源: Karger

摘要:

Cilia were found in intracellular localizations or on the surface of certain cells of frog thymus and chicken parathyroid gland and ultimobranchial body. The experimental observations suggest that ciliogenesis is probably a general property of branchiogenic epithelium, which either persists, or can be activated by certain influences after the functional differentiation of endocrine organs arising from the foregut.

ISSN:1422-6405    

DOI:10.1159/000144632

出版商:S. Karger AG    

年代:1976

数据来源: Karger

摘要:

The osmium tetroxide-zinc iodide technique has been applied to the study of the tela submucosa and tunica muscularis in the esophagus of the cat and the rhesus monkey. Other than the classical terminal vegetative formation, three types of endings were found, classified as perifascicular, free and intramuscular. The comparative results between cat and rhesus monkey show differences in the distribution and number of such endings. A sensory functional significance is proposed and discussed.

ISSN:1422-6405    

DOI:10.1159/000144633

出版商:S. Karger AG    

年代:1976

数据来源: Karger