Acta biologica Academiae Scientiarum Hungaricae最新文献

Chicken embryos were exposed to a single dose of adrenocorticotropic hormone (ACTH) on the 15th day of the incubation period. Five days later, the female embryos showed a significant increase in ovarian weight, ovarian thickness and oocyte count. In contrast, the male embryos showed a significant decreased in testicle weight, seminiferous cord diameter and gonocyte number. The opposite response of testes and ovaries is discussed.

In an in vitro system, the tail absorption of the frog larva was significantly stimulated by cAMP more intensely than by T3. Theophylline, an inhibitor of cPDE, had no effect and failed to enhance, even decreased the effect of T3. It may be supposed that T3 does not act through a cAMP mechanism, but the tail absorption can be influenced by cAMP in a direct way.

The regulatory effect on T lymphocyte proliferation of the differentiator thymosin hormone family (thymosin fr. 5, A. L. Goldstein), Ca2+, and purified inhibitory protein fractions prepared from calf thymus was investigated in C57Bl/6 mice. 1.2 mM Ca2+ concentration was the most favourable for murine thymocyte growth in culture. Net protein synthesis was transitorily inhibited by Cu2+ concentrations higher than 2 mM. This inhibition was followed by a marked inhibition of DNA synthesis 2 hrs later. The effect of thymosin fr. 5 was slight, of short duration, and oscillatory in nature; in contrast, chalone-T preparations inhibited thymocyte DNA synthesis permanently up to 12 hrs of cultivation. When spleen cells taken from mice treated with the immunoadjuvant Bacillus Calmette-Guérin (BCG) were exposed to chalone-T in culture, then stimulated with PHA, a reduced proliferative response was measured in chalone-T pretreated cultures compared to controls or spleen cells from normal non-BCG-activated mice. This result had led us to suggest that chalone-T has a dual effect on thymocytes, viz. it inhibits cell cycle progression and induces the phenotypic conversion of suppressor T lymphocytes. The multifactorial concept of T lymphocyte production is discussed.

Cell suspensions derived from adult rat anterior pituitary glands were cultured for up to eight days. Prolactin immunoreactivity and/or tritiated thymidine incorporation into DNA of cell nuclei were demonstrated in cells with and without thyroliberin (TRH) and somatostatin (SRIF) treatment. It has been established that (a) TRH, which is effective in releasing both thyrotropin and prolactin, may stimulate cell proliferation in other than its target cells; that (b) SRIF has no effect on lactotropic cell proliferation and augments thymidine incorporation into DNA of unidentified cells; that (c) immunoreactive lactotropic cells with tritium-labelled nuclei are present in each culture, independent of hypothalamic hormone treatments.

In estrogen-induced cryptorchidism in mice, differentiation of the epididymis is arrested. Transformation of the Wolffian duct into the epididymis, which is androgen dependent, is incomplete. Simultaneous administration of estrogen and HCG prevents cryptorchidism, and the appearance of the epididymis in the transmission and the scanning electron microscope is similar to the appearance of the epididymis of control animals. According to our studies the epididymis differentiation is a prime mover in a process which leads to the descensus of the testis.

Zenker-fixed paraffin-embedded sections of biopsy liver tissue from 64 cases of primary hepatocellular carcinoma (PHC) were stained for hepatitis B surface antigen (HBsAg) and for hepatitis B core antigen (HBcAg) by histochemical and/or immunohistochemical techniques in a retrospective study. PHC arose in livers with postnecrotic cirrhosis in 30 (46.9%) cases. Controls included liver biopsy sections from 123 miscellaneous liver disorders and from 67 randomly selected autopsy specimens, none of which were known to be associated with hepatitis B virus (HBV) infection. HBsAg was detected in tumorous hepatocytes in only one of the 64 cases of PHC. HBsAg was identified in nontumorous hepatocytes of 8 (20%) of 40 specimens that contained adequate nontumorous liver tissue. All of these HBsAg positive cases of PHC were associated with cirrhosis. Thus HBsAg was detected in 8 (33.3%) of 24 cases of PHC with cirrhosis, but in none of the remaining 16 cases without cirrhosis. HBcAg was not detected in the hepatocytes of those HBsAg positive PHC cases tested. Our results suggest that HBV infection may successively lead to chronic hepatitis, cirrhosis and ultimately PHC.

We have described two types of lymphocyte migration through the HEV. In the first case the lymphocytes do not show constriction ring during the diapedesis. 97% of lymphocytes migrate in this manner. In this migration pattern the lymphocyte gets through the endothelium by means of flexibility and pliability of the endothelium. It is suggested that these lymphocytes migrate into the blood from the lymph node. In the second case the lymphocytes undergo morphological changes, they form constriction ring and they migrate from the blood into the lymph node.

With the aid of the cobalt labelling technique the distribution and morphology of motoneurons were studied in the 2nd and 3rd lumbar segments of the rat's spinal cord. On the basis of arborization patterns of their dendritic arbors, motoneurons can be classified into six groups. 1. Large stellate-form neurons occupy the centre of the ventral horn. 2. Marginal neurons are found at the ventrolateral border of the ventral horn. 3. Horizontal neurons form a small group in the dorsolateral corner of the ventral horn. 4. Upper stellate neurons situate in the dorsal part of the ventral horn. 5. Triangular neurons constitute a compact group in the medial corner of the ventral horn. 6. Unclassifiable neurons form a scattered group in the ventral part of the ventral horn. The arborization pattern of dendrites of adjacent neurons belonging to the same group frequently resemble one another to such an extent that they are called "twin" neurons and derive probably from a common cell lineage. One member of such twin pairs is often the small counterpart of its much bigger mate. Dendrites originating from the same morphological type of motoneurons and running in the same direction, aggregate into smaller or larger bundles. The majority of dendritic bundles is oriented in, or close to, the transversal plane of the spinal cord; a significant number of longitudinal dendrites are found only in the group of triangular neurons innervating the axial musculature. The possibility is discussed that the differentiation of the different forms is determined both by genetic and epigenetic factors during morphogenesis.