Literary Synopsis

Abstract

The investigation of animal spermatozoa and of their development began about 1840 when, as a result of the newly founded theory on cells, the “small sperm animal” came to be recognized as a cellular element. Based on Kölliker’s fundamental observation on invertebrate animals (1841), similar studies were soon being carried out among all classes of animals, particularly the vertebrates. Schweigger-Seidel (1865) gave a pioneer description of the sperm corpuscle (Samenkörperchen) found in amphibians, birds and mammals. He was the first to ascertain that a sperm comprises a whole cell. He contradicted Kölliker’s idea, which was that spermatozoa were nuclear structures formed in other cells. Schweigger-Seidel had previously observed that in the case of birds and mammals two sorts of cells were produced in the seminiferous tubules, of which only one type developed further to become spermatozoa. From his studies of the domestic cock and the chaffinch, Fringilla coelebs, which confirmed observations made by Leuckart (1853), he was able to state that in the avian class two types of spermatozoa are to be distinguished, either being straight and rod-shaped or, as in the case of the songbirds, having a corkscrew-type spiralled head. A somewhat more exact differentiation of the individual segments of avian spermatozoa was given by von Brunn (1884) in his studies of the house sparrow. Like Schweigger-Seidel, he distinguished two sections in the head, as well as a connecting piece, a main piece and an end piece of the tail. Whereas Schweigger-Seidel thought that the connecting piece, which he called middle piece, was part of the head, von Brunn thought it belonged to the tail and therefore recognized the homologous relationship with mammalian spermatozoa.