THE REPRODUCTIVE SYSTEM 369 



Of the large number of ova — estimated at seventy-two thousand in 

 the human ovaries — only comparatively few, according to Henle 

 about four hundred, reach maturity. The majority undergo, to- 

 gether with their follicles, retrogressive changes known as atresia 

 of the follicle. The nucleus of the ovum, as well as the nuclei of 

 the follicular cells, passes through a series of chromatolytic changes, 

 or in some cases apparently simply atrophies. The cell bodies un- 

 dergo fatty or albuminous degeneration and the cells become reduced 

 to a homogeneous mass, which is fmally absorbed, leaving in its 

 place a connective-tissue scar, probably the remains of the theca 

 folliculi. 



Blood-vessels. — The arteries, branches of the ovarian and uterine, 

 enter the ovary at the hilum and ramify in the medulla. From these 

 are given off branches which pass to the cortex and end in a capillary 

 network in the tunica albuginea. In the outer layer of the theca 

 folliculi the capillaries form a wide-meshed network, which gives 

 rise to a fine-meshed network of capillaries in the inner layer of the 

 theca. From the capillaries veins arise which form a plexus in the 

 medulla and leave the ovary at the hilum. 



Lymphatics.^ — These begin as small lymph spaces in the cortex, 

 which communicate with more definite lymph vessels in the medulla, 

 the latter leaving the organ at the hilum. 



Nerves. — INIeduUated and non-medullated fibres enter the ovary 

 at the hilum and follow the course taken by the blood-vessels. Many 

 of the fibres end in the vessel walls; others form plexuses around the 

 follicle and end in the theca foUicuH. Some describe fibres as 

 passing through the theca and ending in the follicular epithelium. 

 Others claim that nerve fibres do not enter the follicle proper. 

 Groups of sympathetic ganglion cells occur in the medulla near the 

 hilum. 



As is the case with the testicle, certain rudimentary organs, the 

 remains of foetal structures, are found connected with the ovary. 



The parobpJwron consists of a number of cords or tubules of epi- 

 theHal cells, sometimes ciliated, sometimes non-ciliated. It is found 

 in the medulla, or, more commonly, in the connective tissue of the 

 hilum. 



The epobpJioron is a similar structure found in the folds of the 

 broad Kgament. Its tubules open into a duct known as Gartner's 

 duct. In man this duct ends blindly. In some of the lower animals 

 it opens into the vagina. Both paroophoron and epoophoron are 



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