In this section we'll look at the reproductive organs, first in the male, then in the female.
In the male, we'll look first at the testes where spermatozoa are formed, then at the pathway by which they reach the urethra, then at the penis.
The testes are contained in the scrotum, the pendulous sac that keeps them at the low temperature needed for spermatogenesis. The thin skin of the scrotum is continuous with the skin of the lower abdominal wall, the upper thigh, and the perineum.
The scrotal skin, which we'll divide, is more or less wrinkled, and the whole scrotum is more or less compact, depending on the action of a fine layer of muscle, the dartos muscle, that lies just beneath the skin. To see the contents of the scrotum, we'll further divide the skin and subcutaneous tissue, along this line.
Here's the testis, protected by a number of covering layers. Here's the spermatic cord. The spermatic cord passes upwards, then laterally to enter the inguinal canal, which is here.
To see the testis and its surrounding layers more clearly, we'll take everything else out of the picture. The testis is surrounded by a thick layer of loose connective tissue, the spermatic fascia, that's formed by the fusion of two developmentally distinct layers, the internal and external spermatic fasciae, that are derived from different layers of the abdominal wall. We'll draw the spermatic fascia aside. Inside it is an inner membranous envelope, the tunica vaginalis, which we've already opened. This is the surface of the testis itself.
The tunica vaginalis creates a fluid-filled envelope around the testis. It's a remnant of peritoneum. Like peritoneum, it has an outer parietal layer, and an inner visceral layer that covers the testis itself.
We'll go to another specimen, to see more of the testis. This is the testis. Here behind it, partly hidden, is the epididymis, through which spermatozoa pass to reach the ductus deferens. The testis, which we've divided longitudinally here, has a tough fibrous coat, the tunica albuginea.
Spermatazoa are formed throughout the testis in the seminiferous tubules, which are just visible here. The seminiferous tubules pass upwards and backwards to converge on this fibrous area, the mediastinum of the testis, where they join to form a network of tubules, the rete testis, that's not visible here.
From the rete testis there emerge between four and twelve efferent ducts or vasa efferentia, which leave the testis, and pass into the upper part of the epididymis.
The epididymis is loosely attached to the posterior aspect of the testis. Here it is, more fully dissected. The epididymis has a head, a body and a tail. In the head of the epididymis the efferent ducts unite to form one tube, the duct of the epididymis. The duct, which is extremely convoluted, makes up almost all the bulk of the epididymis. Spermatozoa mature as they pass along it.
Here at the tail of the epididymis the convolutions of the duct are quite visible. The tail of the epididymis curls around, and becomes continuous with the ductus deferens, which passes upwards to enter the spermatic cord.