490 



URO-GENITAL APPARATUS. 



function of these epitheliums is suddenly developed; the 

 ovarian epithelium gives the signal and ovulation ensues; the 

 epithelium of the uterus, next, becomes very active either in 

 the form of simple menstruation, or of gestation ; lastly, the 

 vaginal epithelium as well as its appendages (external genital 

 organs) does not remain quiescent. 



As the ovary is the seat of origin for most reflex and 

 pathological phenomena we will commence our study with 

 that organ. 



The ovisacs or Graafian vesicles are formed of a little 

 pouch of connective tissue, on whose inner surface a thick 



Graafian vesicle enclosing an ovum.* 



fig. 135. Ovum.t 



layer of small globules are found (membrana gramdosa, Fig. 

 134) ; at one point this layer is a little thicker aud forms the 

 so called proligerous disc (G). One of these globules (E) 

 of the proligerous disc becomes developed to a considerable 

 size, being summoned to a higher destiny than its com- 

 panions, and forms the ovum, the most perfect type of the 

 cellular condition (Fig. 135) ; the ovum attains a size of ^ 

 of a millimetre, and may be visible to the naked eye. 



or 



* A, B, Fibrous layers of the vesicle. C, Membrana granulosa. G, Tunica 

 granulosa or proligerous disc, with the ovum. 1, Vitelline membrane. 2, Vitel- 

 lus or yelk. 3, Germinal vesicle of Purkinje. 



t A, Nucleolus, or germinal spot. B, Nucleus, or germinal vesicle. C, Yelk. 

 D, Vitelline membrane, or cona pellucida. 



