FIG. 154. Early stages in the development of the oosperm of the Rabbit. 



A, two-celled stage, from middle part of the uterine tube, about twenty-two 

 hours after copulation ; B, polyplast or morula stage, from lower end of uterine 

 tube, about the middle of the third day ; C, close of segmentation, from lower 

 end of uterine tube just before entering uterus, seventy hours after copulation ; 

 D, first stage in formation of blastocyst, from uterus, seventy-five hours after 

 copulation ; E, section of blastocyst at the end of fourth day. (x about 

 160.) 



cb, blastomere ; cc, trophoblastic ectoderm ; cd, inner mass of cells (embryonic 

 area) ; cv, cavity of blastocyst ; mo, sperms imbedded in the zona radiata (z) ; 

 n, nucleus. (From Marshall ; A, B, after Bischoff ; C E, after Van Beneden.) 



587 



002 



