Functional and developmental morphology最新文献

With the aim of investigating the predictive value of the Chick Embryotoxicity Screening Test (CHEST) with respect to regulatory rat-rabbit procedures, we compared the results of testing 50 chemicals of different pharmacological properties. Besides all being tested in the alternative technique, 27 substances were tested both in rats and rabbits, 22 only in the rat, and one only in the rabbit, respectively. The predictive value of CHEST with respect to the both official whole-animal procedures was found satisfactory, exhibiting about 80% consistent results. It is argued that the purpose of alternative testing methods is not in replacing the official routine procedures, but in contributing to the development of new predictive systems based on recent teratological knowledge.

The foot of the desert snail, Eremina ehrenbergi, is supplied by branches of the pedal nerves which enter a coarse-meshed peripheral neural plexus. Light and electron microscopic preparations revealed the presence of ganglionic knots embedded in the foot musculature. In these knots the neural cell bodies are found to be situated on the periphery of neuropile. Cross sections through the neuropile demonstrate the presence of many synaptic junctions of the axo-axonic type. In some axon profiles light and dense synaptic vesicles are observed. Some of the axons which constitute the terminal plexus enter into close apposition with muscle cells and definite areas where synaptic transmission in thought to occur are well observed. On the basis of these results it can be concluded that the neural plexus may be involved in the production of the patterned pedal activity in Eremina ehrenbergi.

This paper demonstrates the structure and development of the layer of mm. contrahentes in Felis catus (Carnivora). Ontogenesis of the muscle layer was studied on 35 histological series of embryonal extremities and by microdissections of palmar musculature in the domestic cat. It was found that three mm. contrahentes were formed passing to the first, second and fifth digits. A compact anlage of the muscle layer (similar to that in embryos of many mammalian species) has been observed only in foetuses of 15-16 mm crown-rump length. Differentiation of the anlagen of the individual muscles takes place in the foetuses of 20-23 mm crown-rump length.

The vomeronasal organ (VNO) of the mink is restricted to the area of the Fissura palatina and thus always topographically related to the Ductus incisivus (DI). The VNO and DI have also a functional relation because the vomeronasal duct ends in the incisive duct. On the other hand, as the DI has its mouth in the Papilla incisiva there is a communication between the VNO and the oral cavity. The vomeronasal cartilage, approximately in 1/6 of its length, wraps completely the parenchyma of the VNO whose main structure is the vomeronasal duct, with two different epithelia: sensory receptor in the medial wall, and respiratory in the lateral one. Nevertheless the variations of epithelia belong to the segment of the duct because in its rostral and caudal parts the medial and lateral epithelia are very similar. Branches and tubular PAS positive glands stand out in three points: superior, inferior and medial areas of the vomeronasal duct in which they end. An important number of vessels, mainly veins of different diameter, are located around the duct, while the nervous fibers are close to the medial wall of the duct and very easy to identify in the caudal third of the organ. Two immunohistochemical techniques were used to identify the nerve fibers and the receptor cells.

The effect of cadmium chloride on the pituitary ACTH cells, gonadotropin- and thyrotropin-secreting cells, thyroid gland and gonads of the catfish, Clarias batrachus was investigated. Exposure to cadmium chloride caused a significant increase in the ACTH cell nuclear indices at day 7, 14 and 28, whereas the thyrotropin- and gonadotropin-secreting cells showed inactivation and accumulation of secretary products. The epithelial height of the thyroid follicles was also significantly reduced (P < 0.001) as compared to that of the untreated control fish. In experimental female fish, the gonosomatic index had undergone a significant reduction at all intervals studied (day 7, 14 and 28). However, in the male catfish a significant reduction in the gonosomatic index was observed only after exposure for 28 days. Ovarian maturation seems to have become arrested at perinucleolar stage and spermatogenesis at spermatocyte stage. The possible involvement of the hypothalamo-hypophyseal system in gonadal regression was discussed.

Daily administration of caffeine (30 or 60 mg/kg) to mature male rabbits for four consecutive weeks caused an increase in the plasma follicle stimulating hormone (FSH) and a decrease in the luteinizing hormone (LH). Testosterone was increased with the higher dose only while adrenocorticotrophic hormone (ACTH) was not altered by either one. These results suggest that the effects of caffeine on the two gonadotrophic hormones, FSH and LH, involve two separate pathways. The light microscope study revealed reduced sizes of the seminiferous tubules, inhibited spermatogenesis, fatty degeneration of the liver and hepatic lesions. The adrenal glands exhibited signs of stimulated steroidogenesis. It is concluded that long term intake of caffeine induces suppression of spermatogenesis mainly through inhibition of FSH release and this effect is maintained even in the presence of normal or high levels of testosterone and LH.

Intracytoplasmic filaments were demonstrated in the chondrocytes of articular cartilage of cattle at 82 days post partum and at 3 and 4 years of age using transmission electron microscopy and immunocytochemistry. Samples of cartilage for electron microscopy were processed in a standard way. Immunocytochemical procedures were performed with semithin sections made from the material prepared for electron microscopy after embedding medium and osmium compounds had been eliminated. Vimentin filaments were demonstrated by means of anti-vimentin monoclonal antibody visualized by peroxidase-labelled immunoglobulin. Both techniques showed that intracytoplasmic filaments were situated around the nucleus and only occasionally at the cell periphery, e.g. in cell projections.

The ribosomal RNA (rRNA) synthesis in the proerythroblasts and hepatocytes of the chick embryo was examined using the nucleolar test during embryonic days 5-10 after intraamniotic administration of single doses of cyclosporin A (CsA). Administration of the 0.75 or 7.5 g of CsA 5th day of embryonic development caused a significant decrease in proerythroblasts and hepatocytes numbers with active rRNA synthesis. Five days after the CsA administration, the percentage of proerythroblasts with biosynthetically active nucleoli already did not differ from the control while the decreased numbers of hepatocytes actively synthetizing rRNA remained statistically significant. Our results indicate, that CsA inhibits the rRNA biosynthesis in embryonic immature cells. Depending on the cell type, the effect of CsA and its dynamics may be apparently different.

Seasonal variation of the coloration of the testes due to the presence of melanin pigments was observed in a wild passerine bird Dicrurus adsimillis. The proportion of melanin in the testes is highest in the recrudescence period, when the lipid content is moderate and cholesterol is present in the tissue in trace amounts. In the reproductive period, when lipids are depleted, the melanin content is very low; in this stage, cholesterol is stored in the tissue in large amounts. During the post-reproductive period, melanin pigment and lipids both fall almost to zero level and only traces of cholesterol are to be found. In the recrudescence phase, the amount of all three (i.e. melanin pigment, tissue lipids and cholesterol) rapidly increases. The probable correlation between melanogenesis in testicular tissue and hormones and their lipoid precursors is discussed.