THE PRODUCTION OF SEMEN.
Their first de velopment from the embryonal sexual glands, as well as their external differences from the ovaries, have already been described when speaking of the physiology of the latter. The internal differences from the ovaries are brought about in the following way: While in the ovaries, the epithe limn, covering the surface, grows and sends processes into the interior of the organ, which later on develop into ova and follicles, the same cover ing of the testicles remains passive; but here the canals of the neighbor ing Wolffian bodies penetrate the testicles and there give off the foundation of the permanent seminal canaliculi. The latter, in adults, form the principal part of the organ to which is allotted the task of preparing the semen. In respect of the latter function there exists a marked difference between the ovaries and testicles. The ova, the product of the first of these organs, are found in the embryonal rudiments nearly perfect, and when developed remain here until ovulation, so that the ovary appe,ars less a place of production tlusn a receptacle for the ova. It is different in the testicles. Until puberty, a product of the organ cannot be recognized, and only with sexual maturity do the spermatic cells appear in the semi nal canaliculi. A further important difference is found in the following condition: It is not improbable that all of the ova for the whole period of sexual activity are contained in the primitive layer and that a new pro daction does not occur in post-Retal life; in the testicles there is a con stant new formation of spermatozoa during the same period of life. This difference has a great signific,ance in relation to sterility. The seminal canaliculi (the more exact description of which is here omitted) display as their contents in adults two kinds of cells: the so-called testicular cells, which have no characteristic markings, and which line the inner wall of the canals in childhood only. At puberty are added the so-called sper matic cells, also called spermatoblasts, which show altogether irregular forms, are held together by the formation of net-works, the meshes of which are quite small and contain the above-mentioned testicular cells and also the freed contents of the spermatic cells. As to the genetic re
lation of these two kinds of cells to each other, and even as t,o their phy siological significance, there is no universally accepted belief. The differ ent cell-forms, in all probability, indicate only different degrees of devel opment of originally identical formations. Only this much is certain, that the spermatozoa are formed in cells. But -whether these cells which produce spermatozoa are identical with the above-mentioned spermatic cells, or whether they are descendants of these and the latter only repre sent a kind of supporting tissue, is as yet uncertain. The formation of the semen seems to occur in the following manner: On the above-mentioned cells, the spermatoblasts, which project in a lobular way from the walls into the lumen of the duct, thread-like out growths are formed, while in the cells themselves a vigorous nuclear seg mentation takes place. These nuclear divisions develop into the head of the spermatozoa, which, by the formation of a central portion, are united to the thread-like outgrowths of the cells. The latter become elongated, project from the surface of the cell and are light-refracting; they are the caudal filaments of the spermatozoa. Finally the cell is destroyed and the spermatozoa are free. They are still united in bundles, or are, per haps, to be seen separated in the interstices of the cellular net-work of the seminal canaliculi. These cell-derivatives, which we must discuss more fully, do not indeed alone form the semen, but they have added to them in their migratiou through the male passages the secretions of a number of glands. This secretion is furnished by the gland at the end of the vas deferens, the prostatic glands, the seminal vesicles and Cowper's glands. From the commingling of the spermatozoa and the secretions a fluid is formed, which is colorless, somewhat viscid, ropy, easily coagu lable, imparts a peculiar odor, and is of an alkaline reaction; it is soluble in water and in acids, but is coagulated by alcohol.