ORGANS OF THE BODY. 



541 



mass of vessels. The interstitial tissue is extremely scanty, consisting 

 merely of intersecting bands of fusiform cells, which turn off from the 

 middle muscular tunic of the arteries. Intimately united to this interstitial 

 substance are to be found the venous walls which gape on being cut through. 



For this reason the whole tissue of this so-called hilus stroma has been 

 regarded as composed of the modified walls of vessels, themselves traversed 

 again by smaller vessels (His), recalling to mind the structure of the 

 corpora cavernosa (Rouget). From this 

 it would appear that the spindle cells of 

 the medullary substance are muscular 

 elements ( 163, p. 283), in keeping with 

 which view the fresh stroma of the ovary 

 has been observed to possess the power of 

 contractility by both His and myself. 



Further, numerous pencils of vessels 

 are seen to penetrate from the periphery 

 of the stroma of the hilus between the 

 internal follicles towards the surface of 

 the organ. In this course they supply 

 follicles, as mentioned above, with a 

 dense network of vessels. Prolongations 

 of the latter, however, penetrate still 

 further towards the zone of cortical cells, 

 doubling on themselves, for the greater 

 part, before their arrival in the latter, 

 which remains almost entirely devoid of 

 vascularity. 



But besides being very rich in blood- 

 vessels, the whole stroma of the hilus 

 possesses numerous lymphatics. In the 

 latter, which are similar in their arrange- 

 ment to the veins, the characteristic vas- 

 cular cells of these passages may be every- 

 where rendered visible by treatment with nitrate of silver. 



Their relation to the follicles is of special interest, however. The latter 

 having attained a large size, and having pressed forwards towards the sur- 

 face, may be seen in this position to be surrounded by a dense network of 

 lymphatics, situated principally in the external lamina of the wall of the 

 follicle. According to His the apex of the latter is completely destitute 

 of lymphatics, as also of blood-vessels. Smaller follicles also, as soon as 

 their internal tunic has been developed, are found to present an investing 

 network of lymph canals, even long before they have reached the surface 

 of the organ. 



The numerous nerves of the ovary springing, for the most part, from the 

 genital ganglia, as has been shown by Frankenliailser ( 279), contain 

 medullated and non-medullated fibres, and enter the organ with the 

 arteries. Their ultimate distribution is still obscure. 



Lying between the ovaries and Fallopian tubes a trace of the Wolffian 

 bodies may be seen on either side of the uterus, in the form of a few 

 small tortuous canals, situated in the ala ve-spertilionum. To this the 

 name of the parovarium has been given. The tubules are composed of 

 a fibrous wall, epithelial lining, and transparent contents. 



The chemical composition of the ovary still awaits accurate investiga- 



Fig. 533. Egg of a mammal, 1, one in 

 which a rent lias been made in thezona 

 pellucida (a), allowing the escape (6*) of 

 a portion of the yelk, 6*; c, the pre- 

 germinal vesicle with germinal spot, d ; 

 '2, mature ovum covered with radiating 

 epithelial cells, c; with the chorion, a; 

 and yelk, b. 



