186 EQUINE ANATOMY. 



with the transversalis fascia, it forms the most com- 

 plete covering of the serous parietal layer of the tuni- 

 ca vaginalis, to which it is closely adherent. 



Tunica vaginalis. — Diverticulum of the abdomi- 

 nal cavity, and lined by the peritoneum. Its interior 

 forms a serous sac, which is elongated downwards, in- 

 wards and backwards, and is divided into a parietal 

 layer which lines the inside of the fibrous tunic, and a 

 visceral layer covering the testicle and the spermatic 

 cord. These two layers are made continuous by a pos- 

 terior frgenum. The tunica vaginalis contains usually 

 a certain quantity of serous fluid. 



Testicles. — External conformation : oval, flattened 

 sideways and suspended at the extremity of the sper- 

 matic cord. It has two faces, smooth and round, an in- 

 ferior border convex and free, and a superior border 

 related to the epididymis. It is hanging in the tunica 

 vaginalis, through the testicular or spermatic cord, 

 formed by the spermatic vessels and the vas deferens. 

 Structure : 1 — A fibrous covering or tunica albuginea, 

 which is thicker towards the inner border of the organ 

 where it forms the corpus Higmori ; this membrane is 

 dense and inelastic ; 2 — A tissue proper, greyish yellow 

 pulp contained in the fibrous envelope. It presents the 

 tubuli seminiferi, in the axis of wliich are perceived 

 the spermatozoa and the remains of the spermatic cells. 



