76 



THE VERTEBRATE OVARY AND ITS RELATIONSHIP TO REPRODUCTION 



GERMINAL 

 VESI CLE 



OOPLASMIC 

 MEMBRANE 



PERI VITELLINE 

 SPACE 



ZONA PE LLUCIDA 



FO LLICU LAR 

 EPITHE LIUM 



THE C A INTER N A 

 THECA EXTERNA 



Fig. 46. Diagrammatic representation of the egg of the prototherian mammal. Echidna. 



GERMINAL VESICLI 

 NUCLEUS OF PAN DE R 



N IC A 

 ALBUGI N E A 



THECA EXTERNA 



THECA INTERNA 



GRANULOSA 



LAYER 



ZONA RADIATA 



CLEAR CYT OPLASM 



YOLK SPHERE 



Fig. 47. Diagrammatic drawings of the pendent egg follicle in the ovary of the hen. 

 (A) Low magnification of the entire egg follicle. (B) More detailed view of the blasto- 

 disc portion of the egg, nearing maturity, in relation to the pedicle. The latter supports 

 the follicle and permits the blood vessels to pass into and out of the follicle. Compiled 

 from sections of the developing ovary of the hen. 



process in higher mammals, especially the rabbit. Among other vertebrates 

 ovulation in the hen and frog have been the objects of considerable study. 



a. Process of Ovulation in Higher Mammals 



1) Changing Tissue Conditions Culminating in Egg Discharge from the 

 Ovary. As the Graafian follicle enlarges and matures under the influence of 



