THORAX AND ABDOMEN OF THE HORSE 139 



obliterated by the formation of a yellow body, the corpus luteum. The 

 superficial part of the ovary of the mare is more vascular than the rest : 

 in this respect there is a departure from the usual mammalian arrange- 

 ment in which the most vascular part of the organ (zona vasculosa) is 

 most deep seated, while the superficial stratum (zona parenchymatosa) 

 contains the ovarian follicles. 



The uterine tube.— The uterine tube (of Fallopius) affords a 

 means by which the ova pass from the ovary to the uterus, though there 

 is no anatomical continuity between the tube and the gonad. Each tube 

 is from 25 to 30 cm. long and pursues a very wavy course, especially in 

 that part of it that is in the neighbourhood of the ovary. The first part 

 of the tube, the ampidla} is relatively wide, but the diameter 

 diminishes in that portion, the isthmus, which approaches the uterus. 

 Here, too, the tube becomes straighter. The cranial or ovarian end 

 po.ssesses an ostium - ahdominale tubce that is in direct communication 

 with the peritoneal cavity. The peritoneal cavity of the female, there- 

 fore, differs from serous cavities in general, inasmuch as it communicates 

 (indirectly) with the exterior. The margin of the abdominal ostium is 

 fringed with irregular processes, the fi'mbria' ^ tubce, a few of which, the 

 ovarian Jimbricc (fimbria^ ovaricse), are attached to the cranial lip 

 of the ovulation fossa of the ovary. That portion of the tube formed by 

 the fimbriae is generally designated the infundihulum,^ from its shape. 



The uterine end of the tube (pars uterina tuba?) pi'ojects into the 

 cavity of the cornu as a small, firm papilla, on the summit of which is the 

 small uterine ostium (ostium uterinum tubae). 



The uterine tube is included within a double peritoneal fold, the 

 mesosalpinx, connected with the lateral face of the broad ligament. 

 The mesosalpinx and the proper ligament of the ovary bound a long 

 slit-like opening, ventral in aspect, which leads into the ovarian bursa 

 (bursa ovarii), into which the lateral surface of the ovary projects. 



In young animals a blind, coiled tube, the paroophoron,^ may 

 generally be found in the mesosalpinx between the free border of the 

 ovary and the uterine tube. This is the remains of the embryonic 

 mesonephros. 



If the dissection-subject is a male, the distribution of the con- 



1 Amjndla [L.], a globular vessel, a flask. 



- Ostium, dim. of os [L.], a mouth or orifice, any kind of entrance or exit. 

 ^ Fimbrue (pi. only) [L.], a border, edge, or fringe. 

 * Infundibulnm [L.], a tunnel. 



" -irdpa (para) [Gr.], near, about ; wo<t>6pos (oophoros) [Gr. <^bv (oon), egg -I- 

 ^ipnv (pherein), to bear], the ovary. 



