250 SPECIAL HISTOLOGY. 



body of the embryo, consists of a certain number of canals, 

 0*15 — 0*2' " in diameter, diverging from the hilus ovarii into 

 the ' bat's wing/ which in Man neither open into the ovarium 

 nor are connected with any other parts, and contain nothing 

 but a little clear fluid. The tubes are formed of a fibrous 

 membrane, 0*020 — 024'" thick, and of a single layer of pale, 

 cylindrical, probably ciliated cells, and are of interest only as 

 the remains of an embryonic structure. 



The arteries of the ovary, derived from the aa. spermatica 

 and uterina, and forming numerous minute trunks between 

 the lamelke of the broad ligaments, enter from the inferior 

 border of the ovary, run in a serpentine course in the internal 

 portion of the stroma, and terminate partly in the stroma 

 itself and in the /. albuginea, but chiefly in the walls of 

 the Graafian follicles, where they form an exterior more 

 coarse, and an inner finer plexus, which extends as far as the 

 membrana granulosa. The veins arise in the same situation, 

 are in Man, for the most part very beautifully displayed in 

 the walls of the larger follicles, and terminate in the uterine 

 and internal spermatic veins. A few lymphatic vessels come 

 out from the hilus ovarii, and proceed, in company with the 

 blood-vessels, to the lumbar, and pelvic glands. And with 

 respect to the nerves, they arise from the spermatic plexus, 

 enter as minute trunks with fine fibres, and " fibres of Remak," 

 together with the arteries, into the ovary; but as respects 

 their ultimate condition, they have not yet been investigated. 



§ 205. 



Detachment and re-formation of the ova, — corpora lutea. 

 From the commencement of puberty up to the period of invo- 

 lution, the ovaries are the seat of a continual detachment of the 

 ova by dehiscence of the Graafian vesicles, which, independently 

 of sexual congress, takes place in women and virgins, above all 

 at the menstrual period, although it may and does frequently 

 occur at other times, under conditions not yet accurately deter- 

 mined. In animals the same process is exhibited at the time 

 of " heat," although sexual congress appears to afford a neces- 

 sary impetus to its completion ; and in them the anatomical 

 processes may be more completely traced, whilst, in Man, the 

 opportunity for such observations is much more rarely afforded. 



