similar studies on other strains , as well as reciprocal crosses between balb/c and f1 ( female balb/c x male c57 black ) mice showed that the 'one-cell block ' is determined by the maternal genotype and results most probably from a direct action of x-rays on a radiosensitive cytoplasmic factor necessary for the first embryonic cell division , and appearing 17 h after hcg injection .
C0007634
cell
C0010834
cytoplasmic