[The formation of the human epiphysis and its dynamic development at the stage of early embryonic differentiation].

We studied the epiphysis of human embryos at stages from 18 to 63 mm of occipital-sacral length (OSL). We found that the epiphysis is formed by migration of cells from the roof of the diencephalon in the dorso-caudal direction. At this time, the epiphysis undergoes active vascularization, initially through pinealocytes filling the space between capillaries, and then by the ingrowth of the bundle of nerves and vessels into the epiphysis. The nerve entering the epiphysis, together with vessels, subsequently becomes a source of innervation for the epiphysis of the adult human. Analysis of qualitative correlations between epiphysis development and linear growth of the embryo has demonstrated that the rate of the increase of epiphyseal volume is significantly higher than the rate of the increase of the embryo's occipital-sacral length. Asynchrony in the rate of growth of epiphysis and embryo is highly individual, since increase in volume per 1 mm of length may differ at different stages by a factor of two or even more.