OVARIES. -_M:; 



and often some stages are found to have been completed in the 

 newborn and in foetuses. The above-described ovum, however, 

 is not yet capable of being fertilized. In order to reach this 

 stage, it must undergo the ripening processes, which consist in 

 the so-called reduction of chromosomes. The extrusion of 

 botli polar bodies in lower animals has been discussed in treat- 

 ing of fertilization in general. In higher animals (including 

 man) the ripening takes place in the ovary. The second polar 

 body is extruded shortly before the bursting of the follicle and 

 the escape of the ovum. 



The theca folliculi come in contact with the tunica albuginea 

 of the ovary as the follicle moves to the surface. The cover- 

 ings of the follicle become gradually thinner, but the true reason 

 for the rupture of the follicle is not clear. It is probable that 

 many forces act simultaneously. The increase in the liquor 

 folliculi, the marked congestion which is characteristic of the 

 tissues in ovulation, the swelling of the ovary, and possibly the 

 contraction of smooth muscle contained in the stroma, may 

 help in this process. At the same time the walls of the follicle 

 at the place of bursting become thin and atrophic on account 

 of the obliteration of blood-vessels by pressure. Meanwhile 

 the connection between the ovum and the cells of the discus 

 proligerus arid membrana granulosa becomes looser, and finally 

 disappears, so that the ovum comes to lie in the liquor fol- 

 liculi. During the bursting of the follicle the liquor folliculi 

 as well as the ovum is cast out into the peritoneal cavity. 



After the ovum has escaped, there is always a certain 

 amount of blood which fills up the empty follicle. This 

 becomes a closed cavity containing a blood-clot, which begins 

 to undergo organization. This is known as the corpus hcemor- 

 rhagicum. The organization takes place by a formation of 

 fibrin, and the ingrowth of the so-called lutein cells from 

 the periphery of the follicle. The origin of the lutein cells 

 is not clearly understood. They were described first in 1827 

 by v. Baer, who considered them as a derivative of the theca 

 interna cells. Later on, Bischoff studied this subject, and 

 came to the conclusion that they were derived from the fol- 



