[Formation of the ultrastructure and adrenergic innervation of magistral vessel walls in chicken ontogenesis].
Histochemical and electron microscopic investigation on dynamics of ultrastructure and adrenergic innervation formation in the wall of the femoral artery and vein, in the mesenteric artery and vein and in the aorta has been performed in 10-20-day-old chick embryos and in chickens during first days of life. In the course of embryogenesis, myoblasts of the media tunica have been demonstrated to transform into highly differentiated and strictly specialized smooth muscle cells. Simultaneously, neural fibres from the periphery of the vascular wall gradually penetrate up to the border of the external tunica and tunica media and varicosities with axoplasmic vesicles appear along their course. Owing to these two processes, by the time of hatching, the vascular wall has possessed a certain morphological substrate for the neural-muscular relations.