[Histogenesis of chicken aorta endothelium]

The formation of tissue properties of the aorta endothelium of two-week chicken embryos, and one day chickens has been followed. The morphological characteristics of the aorta endothelial lining in adult chickens are given. The endothelium was studied in tangential sections and flat film preparations. Histological certain histochemical and biometrical methods were used. At the end of the second week the signs of a heteromorphous state of the endothelium were already seen most distinctly, which appeared as early as the end of the first week of embryogenesis. Later these signs accumulated and became stronger. The aorta endothelial lining of adult chickens is polymorphous. Certain regularities in the regional distribution of cells of a definite shape and area were observed in it. Throughout embryogenesis the endothelium behaved like a tissue having its oun cambium. The mitotic index drops in the course of embryogenesis. No mitoses have been found in the endothelial lining of adult chickens.