128 



ANATOMY OF THE RABBIT 



that the primary connections of the kid- 

 ney tubules are with the coelomic cavity 

 (Fig. 73, B). 



The Testis and its Duct 



The male gonad, or testis (Fig. 81), 

 is composed mainly of convoluted semini- 

 ferous tubules, held together by layers of 

 connective tissue, and in the walls of these 

 tubules the male germ cells, the sperma- 

 tozoa, are developed. In a transverse sec- 

 tion of a tubule, cells with dark nuclei 

 appear in the outer or basal row (Fig. 76). 

 These, krown as spermatogonia, produce 

 cells (spermatocytes) which are transformed 

 through several intermediate steps into 

 spermatozoa the latter then passing from 

 the tubules to the epididymis. In the rab- 

 bit, as in all mam.mals, the testis is con- 

 nected with the peripheral duct system 

 (Fig. 75) by means of the epididymis and 

 the ductus deferens, which are parts of 

 the mesonephric connections of the em- 

 bryo. While the ductus deferens is a 



Fig. 76. Small part of a section of the testis of a 

 rabbit showing two seminiferous tubules, sc. 

 spermatocytes; sg, .spermatogonia; sz. heads of 

 newly formed spermatozoa. 



Fig. 75. The male urino- 

 genital ducts and related 

 structures viewed from the 

 lateral surface: a, anal aper- 

 ture; b, bulbourethral gland; 

 c, end of crus penis cut from 

 its attachment to the ischium; 

 dd, ductus deferens; gi, brown 

 portion of inguinal gland; gr, 

 rectal gland; i, white portion 

 of inguinal gland; 1, pars 

 libera penis; mi, ischiocaver- 

 nosus muscle; p, paraprostatic 

 glands; pr, prostate gland; r, 

 rectum; s, inguinal space; u, 

 urethra (membranous por- 

 tion); ur, ureter (these 

 stumps should be directed 

 more backward, to pass under 

 the deferent ducts) ; v, vesi- 

 cular gland; vs, seminal 

 vesicle; vu, urinary bladder. 



single tube, the epididymis 

 consists of an aggregation 

 of small tubules, lying chief- 

 ly toward the anterior end 

 of the testis, but with the 

 tubules not individually 

 discernible. In the embryo 



