cauda epididymidis behind. The latter expands posteriorly and curves down around the posterior end of the testis. The ductus deferens is the conspicuous tube which passes forward from the median side of the cauda epididymidis, through the inguinal canal into the abdominal cavity.
The epididymis and ductus deferens are both attached to a mesentery which extends from the dorsal side of the testis to the dorsal wall of the scrotal cavity. Anteriorly this mesentery also incloses the blood vessels which carry blood to and away from the testis. Fat accumulates in consider- able quantity in front of the epididymis and within ventral prolongations of the mesentery which extend through the inguinal canal into the abdominal cavity.
The mammalian scrotal cavity, like the abdominal cavity from which it is derived, is lined with peritoneum, the tunica vaginalis. The testis, like the intestine, is almost completely invested with peritoneum and is suspended in the scrotal cavity by the mesentery, which is covered on both sides by the peritoneal layer. The wall of the testis is a very tough, fibrous, transparent membrane, the tunica albuginea. This incloses a mass of convoluted seminiferous tubules, readily seen through the tunic. Slit the latter lengthwise of the testis and with a needle tease out some of the tubules, noting their convolutions. These tubules produce the spermatozoa.
The epididymis is covered by a tough transparent membrane similar to the tunica albuginea of the testis. Through the membrane may be seen tubular convolutions. The ductus deferens becomes coiled when it enters the cauda epididymidis. Verify this by a careful dissection.
In man the spermatozoa, produced by the epithelial lining of the seminiferous tubules, pass through efferent ducts, the ductuli efferentes testis, to the caput epididymidis, where they are collected into a single duct, the duct of the
