THE OVARIES. 



1993 



FIG. 1692. 



The veins follow the general arrangement of the arteries within the cortex and 

 medulla ; the pairs of parallel veins, however, do not unite into single stems, but 

 emerge from the hilum as independent tortuous trunks. Within the mesovarium they 

 are interwoven with the bundles of involuntary muscle, and when distended present 

 a conspicuous venous complex {bulbus ovarii). The veins proceeding from the 

 ovary (vv. ovaricce proprice] become tributary to both the uterine and the ovarian 

 (pampiniform) plexus. 



The lymphatics begin in the cortex as net-works within the thecae surrounding 

 the Graafian follicles and as lymphatic clefts within the ovarian stroma. From these 

 radicles the larger and irregular channels enter the medulla, where they form con- 

 verging stems that follow the blood-vessels and leave the hilum of the ovary usu- 

 ally as nine larger trunks (Polano) that pass upward along the free border of the 

 suspensory ligament and empty into the lumbar lymph-nodes surrounding the aorta. 

 Occasionally, but by no means constantly, the 

 ovarian lymphatics communicate with those 

 from the fundus of the uterus and the oviduct. 



The nerves supplying the ovary are de- 

 rived from the sympathetic plexus surrounding 

 the ovarian artery (plexus arteriae ovaricse), 

 which, in turn, is formed by contributions from 

 the renal and aortic plexuses and corresponds 

 to the spermatic plexus in the male. The 

 small nerve-trunks, composed for the most 

 part of non-medullated fibres, accompany the 

 arteries through the hilum into the ovary, 

 where they are distributed chiefly to the walls 

 of the blood-vessels, around the larger of which 

 terminal plexuses are formed. From the fairly 

 close plexus within the cortex, additional mi- 

 nute twigs pass to the periphery, to end in 

 close relation with the surface (germinal) epi- 

 thelium, and others to the follicles. The ulti- 

 mate relation between the latter and the sur- 

 rounding net-works is uncertain, but it is probable that the nerve-fibrillae end in the 

 walls of the follicular blood-vessels and do not penetrate beyond the inner tunic of 

 the theca, the terminations within the follicular epithelium described by some ob- 

 servers needing confirmation. Sensory fibres are probably contained within the 

 cortical branches. The claimed existence of minute, true, sympathetic ganglia within 

 the medulla, has not been established. 



Development. The primary development proceeds from the indifferent 

 germinal ridge which is early formed on the median surface of the Wolffian body 

 (page 2038). Whether, as usually accepted, the ova in common with the follicular 

 epithelium are directly derived from the modified mesothelium (germinal epithelium) 

 covering the sexual ridge, or are the descendants of germ-cells early set apart from 

 the somatic cells for the special role of reproduction, remains to be decided, al- 

 though evidence in support of this latter hypothesis the continuity of the germ- 

 cells is accumulating from observations on the lower animals, in which the origin of 

 the primordial sex-cells is less obscured. 



In human embryos of 12 mm. in length, among the cells of the germinal ridge, 

 certain elements are already distinguished by their exceptional size and large, clear 

 nuclei. These are the primary sexual cells, the primordial ova (Fig. 1717), usually 

 regarded as originating from the transformation of the germinal epithelium. At 

 first the latter and the subjacent stroma of the Wolffian body are well differentiated 

 from each other. This demarcation is soon lost in consequence of the active inter- 

 growth which takes place between the proliferating germinal epithelium and the in- 

 growing vascular connective tissue of the Wolffian body the two chief factors in 

 the histogenesis of the ovary. 



As the mass of epithelial elements increases, it becomes broken up by the con- 

 nective-tissue strands into large tracts, composed of the primary ova surrounded by 



Arteria propria 



Ovarian artery 



Ovarian 

 veins 



Diagram illustrating arrangement of blood- 

 vessels of ovary. (Cfttrk.) 



