. Comparative anatomy. Anatomy, Comparative. THE UROGENITAL SYSTEM 427 tion of cells beginning in the basal layers. During this process a reductional or maturation division takes place previous to the meta- morphosis of the cells into mature spermatozoa. All transitional stages in the conversion of epithelial cells into spermatozoa may be seen in a cross section of the seminiferous tubules. The Sertoli cells which occur among the germ-cells are usually assumed to have a nutritive function. As the spermatozoa lose connexion with the epithelium, they pass into the lumen of the tubules, and thus
. Comparative anatomy. Anatomy, Comparative. THE UROGENITAL SYSTEM 427 tion of cells beginning in the basal layers. During this process a reductional or maturation division takes place previous to the meta- morphosis of the cells into mature spermatozoa. All transitional stages in the conversion of epithelial cells into spermatozoa may be seen in a cross section of the seminiferous tubules. The Sertoli cells which occur among the germ-cells are usually assumed to have a nutritive function. As the spermatozoa lose connexion with the epithelium, they pass into the lumen of the tubules, and thus find their way to the epididymis, in which they may be retained for some time. They are contained in a mucous alkaline liquid, also secreted by the epithelium of the seminifer-. SPERMATIC- CORD. PUBIC SYMPHYSIS CORPUS CAVERNOSUM PENIS. CORPUS- CAVERNOSUM URETHRAE UROGENITAL "DIAPHRAGM. •BULBOURETHRAL GLAND. BULBUS. •RECTUM- EXTERNAL -SPHINCTER MUSCLE. -ANUS. Fig. 352.—The urogenital system—male. The glandular complications of the male urogenital system appear to be in part an adaptation to the double function of the urethra—excretory and reproductive. The alkaline secretions of the glands serve to neutralize the acidity of the urethra caused by the acid urine. (Sobotta.) ous tubules. Diminution in the activity of the tubules is seen in old age, and may begin as early as thirty-five years. The interstitial tissue between the seminiferous tubules is believed to have an endocrinal function and to influence the development of secondary sex traits and the vigor of the individual. Also associated with the testes are certain rudimentary organs, ductuli aberrantes, paradidymis, hydatid of Morgagni, the significance of which will be better understood after the description of their develop- ment. Each testis is attached to the scrotum by a connective tissue cord, the gubemaculum. Ductus Deferens. By the efferent ducts of the testis, sperm is carried to the ductus epididymi
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