426 ORGANS OF REPRODUCTION 



follicle develops and ripens or matures periodically, 

 about every twenty-eight days. When mature the 

 vesicle ruptures and the ovum and liquid contents 

 of the vesicle are discharged. The ovum is received 

 by the fimbriated extremity of the Fallopian tube, 

 enters its cavity, wherein it is transferred through the 

 tube by the peristaltic action of its muscle fibers, aided 

 by the cilia of the lining epithelial cells, into the 

 body of the uterus, where it is fertilized, when mature, 

 by the spermatozoa the germ cell of the male. The 

 ovum may be fertilized in the Fallopian tube. The 

 passage of the ovum from the ovary to the uterus 

 occupies approximately four to ten days. The ovum 

 undergoes a succession of changes, particularly the 

 nucleus, after it leaves the ovary before fertilization 

 can occur. (See Maturation, p. 35.) 



Corpus luteum is a yellowish body which is present 

 in the ovum following the rupture of the Graafian 

 follicle and the ovum escapes into the oviduct (ovula- 

 tion). When the follicle ruptures the antrum fills with 

 blood and forms the corpus hemorrhagicum. This body 

 becomes organized and the hemoglobin is absorbed, 

 which leaves a yellowish body, due to the presence 

 of many large yellow cells called lutein cells. The 

 corpus luteum occurs every twenty-eight days. If 

 fecundation occurs the corpus luteum persists in the 

 ovum as a yellowish body as described above, and 

 persists throughout the term of pregnancy. How- 

 ever, if fecundation does not occur the corpus luteum 

 shortly contracts, becomes whitish and forms the corpus 

 albicans. 



The latter change is supposed to be due to a fatty 

 degeneration of the lutein cells. The corpus luteum 

 is considered a periodic self-developing gland with an 

 internal secretion. Ovulation and menstruation have 

 a close relationship. Menstruation signifies a frus- 

 trated ovulation and the discharge of a hyperemic 

 membrane from the uterus. Rupture of the Graafian 



