State of the hypophysis in the hiemal and vernal forms of the Russian sturgeon Acipenser Gueldenstaedtii of the Volga after holding and hormonal treatment

Abstract

Hiemal and vernal forms of Russian Sturgeon Aci� penser gueldenstaedtii (Barannikova, 1975) migrating to the Volga to spawn with a different state of sex glands are described in its VolgaCaspian population. The relatively scanty vernal form and more numerous hiemal sturgeon, whose migration continues from ver� nal to autumn, are usually distinguished. The sum� mermigrant hiemal sturgeon is the farthest from maturity at the beginning of the river period of anadro� mous migration, and the autumnmigrant hiemal sturgeon goes into the river with more mature sex products. The vernal sturgeon migrates into the river in a state close to maturity in vernal and, after it is kept for a short period at fish hatcheries, mature sex cells are obtained from it with the help of hormonal injections. High basophilic cells that are close to the completion of the secretory cycle and are gonadotropes dominate in the distal pituitary lobe of these sturgeons, mainly in the ventral zone. The analysis of the ultrastructure has shown the presence of dark and light cells rich in the secretion as well as pictures of exhaustion of separate gonadotropes (Barannikova et al., 1984).