A CYTOLOGICAL OBSERVATION ON GYNOGENESIS OF CRUCIAN CARP (CARASSIUS AURATUS GIBELIO)

The purpose of our investigation was to examine whether the crucian carp caught from Shuangfeng reservoir in Fangzheng County, Heilongjiang Province, would reproduce by gynogenesis. Their spawn were artificially inseminated with milt of red carp (Cyprinus carpio L. red variety), and a nmnber of fertilized eggs were studied cytologically before their first cleavages. The results of observation are as follows:1. In the fertilized eggs, the sperm nucleus remained as a condensed mass and did not transform into male pronucleus; no amphimixis was observed.2. No polar body was found in the ripe egg cells just after spawning, and about 10 minutes after insemination (at 19°—21℃ water), a single polar body was extruded.3. In the spawn of one and the same crueian carp, a great majority of eggs contained metaphase nucleus derived from a maturation division; in these eggs development could proceed following the entrance of spermatozoon; that is, gynogenesis occurred, with the extrusion of a single polar body. However, a few eggs in the same batch contained nucleus with tripolar spindle formation at 7 minutes after insemination; such formation was probably an indication of upsetting maturation division.The results of the present observation indicated that the erucian carp caught from Shuangfeng reservoir did reproduce by gynogenesis.