200 



ELEMENTS OF BIOLOGY 



the tubules are composed of two types o£ cells, spermatozoa in vari- 

 ous stages of maturation, and large nurse cells known as Sertoli 

 CELLS. Spermatozoa are being continuously matured during adult 

 life and are stored in the seminal vesicles. 



Reproductive System of the Human Female. The human 

 ovary (Fig. 137) consists of two portions, a core or medullary por- 

 tion and the cortex. The ova originate in connection with the 



FALLOPIAN TUBE 



OVUM 



GRAAFIAN FOLLICLE 



CORTEX 



CORPUS LUTEUM 



UTERUS 



OVARr 



OVARIAN LIGAMENT 



MEDULLA 



BROAD LIGAMENT 



Fig. 137. — ^The position and structure of the human ovary. (Partly after Sobotta: 

 Adas and Texthoof{ of Human Anatomy, published by W. B. Saunders Co.) 



epithelium of the cortex and as they mature sink deeply into the 

 cortical tissue. The epithelium and cortex appear to contain many 

 thousands of primordial ova but only a few hundred mature during 

 the life of the individual. Around each maturing ovum a special 

 organ is formed, known as the graafian follicle (Fig. 137). The 

 cells forming the follicle have a glandular function and secrete a 

 liquid that fills the cavity of the mature structure. In some mam- 

 mals at least, the follicular liquid contains hormones (p. 203) that 

 have to do with certain psychical sex attributes and with body 



