OVULATION AND EGG TRANSPORT 



119 



RANA PIPIENS 



PIGMENT 



ANIMAL POLE 



i , GERMINAL VESICLE 



CHROMOSOMES 

 , VITELLINE MEMBRANE 



FIRST MATURATION OMSICN 



FIRST POLAR 800Y 



METAPHASE OF 

 SECOND MATURATION FIRST POLAR BODY 



MATURATION COMPLETED • 2 POLAR BODIES 



UTERirC EGG AT MOMENT 

 OF FERTUZATION 



SWOLLEN LAYERS OF JELLY 



MATURATION AND FERTILIZATION OF THE FROG'S EGG 



(RANA RPIENS) 



Growth period of egg and development of vitelline memorane — May to September. 

 Hibernation period, no changes — October to March. 



Natural in March * April 



Breakdown of germinal vesicle - at time of ovulation 



Induced September to March 



Elimination of first polar body - during transit through oviduct (Jelly applied 



from oviduct) . 

 Second maturation to raetaphase stage - in uterus, and until fertilization or death. 



Elimination of second polar body - 15 - 30 minutes after insemination. 

 Jelly swells rapidly when egg is placed in water. 



Fusion of pronuclei - li - 2 hours after insemination. 



First cleavage - 2i hours after insemination. 



