[Relationship between spawning and the neurohypophyseal glia and leukocytes of the sturgeon Acipenser güldenstädti].

Lymphocytes have been revealed in the neurohypophyseal tissue of the female sturgeon during upstream migration soon and 1--1 1/2 month after spawning. Direct relationship was established between the state of neurosecretory elements, neuroglia and the number of lymphocytes. Hypertrophy and hyperplasia of tanycytes and pituicytes together with the increase in the number of lymphocytes, as well as the activation of neurosecretory terminals (the decrease in total amount of neurosecretory material) and hyperemia of the neurohypophysis were observed after spawning. It is suggested that during this period phagocytic activity of the pituicytes and leucocytes is increased. The tanycytes, being evidently more ancient elements of neurohypophyseal neuroglia typical of cyclostromes and fishes, exhibit essentially the same high reactivity as pituicytes which constitute the main glial element of the posterior pituitary in quadripedes. The described infiltration of the heurohypophyseal tissue by leucocytes in Acipenseridae is presumably characteristic of lower vertebrates only.