Cytological studies on two differential development modes of the allogynogenetic silver crucian carp multiple tetraploid

The present paper reports different development modes in the eggs of the allogynogenetic silver crucian carp,which was found in the artificial breeding population of Carassius auratus gibelio ( female ) X Cyprinus carpio red variety ( male ). The development process of two groups, multiple tetraploid allogynogenetic silver crucian carp ( female ) X crucian carp (Carassius auratus gibelio) ( female )and multiple tetraploid allogynogenetic silver crucian carp( female ) X red carp ( male ), were observed. It was found that,in the 2nd group, the sperms of the red carp do not decondense and transform into a male pronucleus after having penetrated into the ovum of the multiple tetraploid allogynogenetic silver crucian carp (plate II ). That is a typical process of allogynogenesis. However, in the first group,the sperms of crucian carp have general process of decondensation formation of pronucleus and conjoint with the female pronucleus. It is so similar to the process of the amphimixis that We call it pseudoamphimixis temporarily (Plate I,) Moreover in the 1st group, it has been found in most seetions that some of chromosomes had been excluded outside when the most of chromosomes had been arranged at the equator of the spindle at midstage of the first cleavage of fertilized eggs. The mechanism of allogynogenesis in the eggs of multiple tetraploid allogynogenetic silver crucian carp is discussed.