1130 



THE REPRODUCTIVE ORGANS 



zona pellucida. The entire follicle is marked off against the now very vascular 

 connective tissue stroma by the membrana granulosa. 



The Mature Graafian Follicle. Beginning shortly after birth, 

 the developing primordial follicles pass from the inner realm of the 

 cortex toward its periphery, but do not actually reach the surface. 

 Later on, however, the more superficial ones pursue the same course 

 and actually appear externally in the form of projecting vesicular 

 bodies, the diameter of which varies between 2 and 15 mm. The outer 

 wall of these vesicles is thin and nearly bloodless (stigma), while their 

 remaining investment is really more vascular than previously. At 

 this time, therefore, the projecting Graafian follicle consists of a 



FIG. 537. GRAAFIAN FOLLICLE OF MAMMALIAN OVARY. 



ov, Ovum; dp, discus proligerus; Iq.f, liquor folliculi; ch, theca; gr. membrana granu- 

 losa. (Prenant and Bouin.) 



connective tissue investment, or theca follicula, an epithelial covering, 

 or membrana granulosa, the ovum, and the liquor folliculi. The ovum 

 itself now measures 0.2 mm. in diameter, as against 48 to 69 n when 

 first formed, and contains large numbers of irregularly shaped and 

 highly refractive granules, the so-called deuteroplasm. Its nucleus 

 or germinal vesicle presents a well differentiated nucleolus, or germinal 

 spot. It is also of interest to note that the connective tissue stroma 

 gives rise at this time to a peculiar type of cells which contain a yel- 

 lowish pigment and are destined to play an important role later on 

 in the formation of the corpus luteum. 



