Henry Gray (18251861). Anatomy of the Human Body. 1918.
the fact that their cytoplasm has no affinity for ordinary stains, but assumes a brownish tinge when treated by osmic acid. The path along which they travel into the embryo is a very definite one, viz., from the yolk sac upward between the splanchnopleure and gut in the hinder portion of the embryo. This pathway, named by Beard the germinal path, leads them directly to the position which they ought finally to take up in the `germinal ridge' or nidus. A considerable number apparently never reach their proper destination, since vagrant germ cells are found in all sorts of places, but more particularly on the mesentery. Some of these may possibly find their way into the germinal ridge; some probably undergo atrophy, while others may persist and become the seat of dermoid tumors.
The Testis.The testis is developed in much the same way as the ovary. Like the ovary, in its earliest stages it consists of a central mass of epithelium covered by a surface epithelium. In the central mass a series of cords appear (Fig. 1114), and the periphery of the mass is converted into the tunica albuginea, thus excluding the surface epithelium from any part in the formation of the tissue of the testis. The cords of the central mass run together toward the future hilus and form a network which ultimately becomes the rete testis. From the cords the seminiferous tubules are developed, and between them connective-tissue septa extend. The seminiferous tubules become connected with outgrowths from the Wolffian body, which, as before mentioned, form the efferent ducts of the testis.
FIG. 1114 Section of a genital cord of the testis of a human embryo 3.5 cm. long. (Felix and Bühler.) (See enlarged image)
Descent of the Testes.The testes, at an early period of fetal life, are placed at the back part of the abdominal cavity, behind the peritoneum, and each is attached by a peritoneal fold, the mesorchium, to the mesonephros. From the front of the mesonephros a fold of peritoneum termed the inguinal fold grows forward to meet and fuse with a peritoneal fold, the inguinal crest, which grows backward from the