96 _ ANATOMY OF THE RABBIT. 
with the coelomic cavity (Fig. 51 B). Their ciliated internal 
openings, termed nephrostomes, are not developed in specialized 
kidneys, but may be seen, even in the adult condition, in some 
lampreys, where they communicate with that portion of the body 
cavity enclosing the heart. 
In the rabbit, as in all mammals, the male gonad or testis (Fig. 55), 
in which the male germ cells, 
spermatozoa, are matured, 
is connected with the peri- 
pheral duct system (Fig. 52) 
by means of the epididymis 
and the ductus deferens, 
parts of the mesonephric 
connections of the embryo. 
While the ductus deferens is a 
single tube, the epididymis 
THE consists of an ag- 
TESTIS gregation of small 
AND _ tubules, lying chiefly 
IT'S toward the anterior 
puck end of the testis, 
but with the tubules not 
individually discernible. The 
testis is formed in the embryo 
Fic. 53. Thefemale urinogenital system: a, all vertebrates a associa- 
aorta: as, internal spermatic artery; au, umbilical tion with the dorsal abdo- 
artery; c, clitoris; gp, perineal gland; gr, rectal 4 * 
gland; h, hydatid of uterine tube; hr, middle minal wall, but in many 
hemorrhoidal artery; i, inferior caval vein; lo, 
ovarian ligament; It, round ligament; lu, umbilical mammals moves backward to 
ligament; ms, mesosalpinx; mt, mesometrium; SIN . 
0, Ovary; ot, ostium tube; r, rectum; rp, peritoneal a scrotal position, either 
recess (rudimentary vaginal process); cu, uterine f i 
ie es AG Meat We artes re ees peciodically ge penn cary 
in the course of development. 
This change, known as the descent of the testis, is brought about 
through the agency of a muscular cord, the gubernaculum, the 
connections of which in the rabbit, are retained in the adult condi- 
tion. The migration of the organ determines a number of peculiar- 
ities in the relations of its bloodvessels and peritoneal connections. 
The female gonad or ovary (Fig. 53) lies on the dorsal wall of the 
abdominal cavity, thus retaining to a large extent the primitive 

