OOGENESIS J 



1. Examine a fresh ovary of a pig and note the numerous more or less 

 transparent prominences (Graafian follicles) of various sizes in which 

 the egg cells develop. The more mature follicles are larger and more 

 transparent. Note also the hard, yellowish substance (corpora lutea) 

 with which the cavity of a follicle is filled after the mature egg has been 

 discharged. Make an enlarged drawing of the entire ovary to show the 

 structure as observed. 



2. Examine, with the low power, a prepared section of a mouse ovary. 

 Note the outer covering (germinal epithelium) in which the eggs are 

 first formed and from which they move into the body of the ovary, where 

 they become surrounded by follicle cells, and thus form the Graafian 

 follicles. The latter can be seen in various stages of development. In 

 the immature follicles the large central egg is closely surrounded by sev- 

 eral layers of the follicle cells. In the larger, more mature follicles, a 

 liquid-filled cavity develops around the egg. In close contact to the egg 

 are a few layers of the follicle cells which also support it at one point. 

 Areas of the yellowish corpora lutea can also be seen in the preparation. 

 The ground substance of the ovary consists of connective tissue with the 

 numerous cells and blood vessels embedded in it. Draw the entire ovary 

 in outline and fill in a portion to show the structure as observed. 



3. Select the most mature follicle containing an egg with nucleus which 

 your preparation shows. Study it carefully with the high power and 

 draw the entire follicle in detail. 



1 B. pp. 205-206. 



355 



