[Effect of thyroxine and methylthiouracil on the development of intramural ganglia in the chick embryo digestive tube]. / Vliianie tiroksina i metiltiouratsilla na razvitie intramural'nykh uzlov pishchevaritel'noi trubki kurinogo émbriona.

The development of the vegetative muscular-gastric plexus ganglia has been studied in 17-day-old chick embryos at administration of thyroxin and the inhibitor of its production - methylthiouracil. The substances in question are injected into the air chamber of the egg on the 3d days of incubation. In histological preparations, stained after Nissl, with hematoxylin - eosin and silver impregnated, the total number of cells of the neuroblastic line and that of differentiated neurons are calculated in 50 ganglia. Under thyroxin effect the number of the differentiated neurons in the ganglia increases, while the total number of the neuroblastic cells (comparing to the control) remains constant. Under methylthiouracil effect the number of the differentiated neurons decreases and so does the total number of the neuroblastic cells. Thyroxin and methylthiouracil differently affect the differentiation rate of the neurons at various stages of this process. The effect of the drugs applied is poorly manifested in the duodenum, where (in the control) the total portion of the differentiated cells is higher than in other segments of the digestive tube, and the number of the ganglia without such cells is lower, while the portion of the ganglia with numerous differentiated neurons is more significant.

[Development of intramural ganglia of the gastrointestinal tract in embryo rabbits under conditions of thyroidin loading of the mother's body]. / Razvitie intramural'nykh gangliev pishchevaritel'noi trubki u zarodyshei krolika v usloviiakh tireoidinovoi nagruzki materinskogo organizma.

Ganglia of myenteric plexus in 13-, 15.5-, 16.5-, 19.5-, 25-, 27- and 29-day-old rabbit embryos, as well as in newborn rabbits delivered under experimentally induced thyrotoxicosis in the maternal organism during gestation were studied and compared with those of control animals at the same age. Different methods of silver impregnation, hematoxylin--eosin staining and Nissl's method were used. Total amount of nervous cells and differentiated neurons were counted; numerical data were statistically treated. At early stages of embryogenesis, there were no differences in migration processes, in laying and differentiation of nervous elements in the intramural ganglia of the intestinal tubes of the test and control embryos, that is in accordance with literature data on the placental barrier nonpermeability for the thyroid hormones at that time. Thyroidin stimulates the intramural ganglia development, growth of their neurons, stipulated by cytoplasmic protein synthesis. The experimental results were seen in increasing amount of highly differentiated multipolar neurons in the embryos before birth and in the newborn animals in comparison with the control. In lower vertebrates, thyroxine was stated by Coujard (1950) to influence the earliest stages of the intramural ganglia laying as a result of stimulation effect on the migrational movements of neuroblasts.