Megalospermatozyten: Degeneration von Spermatozyten I im alternden Hoden des Menschen

Megalospermatocytes in the human testis exhibit asynapsis of chromosomes

Testis biopsies of three infertile patients were identified, which showed a predomination of megalospermatocytes in the seminiferous tubules. Megalospermatocytes are very large primary spermatocytes indicating a spermatogenic arrest. Because of the high percentage of these germ cells it was possible to apply a whole-mount spreading technique to investigate the chromosomal pairing behaviour in prophase I of meiosis. It could be shown that most of the megalospermatocytes exhibited extensive chromosomal asynapsis, suggesting that a characteristic meiotic disorder may give rise to reduced fertility, or even infertility.

Intercellular bridges between megalospermatocytes in the human testis

The occurrence of intercellular bridges connecting megalospermatocytes in the human testis has been documented by means of light and electron microscopy. Thereby, the clonal character of this special form of male germ cell degeneration has been substantiated. In the course of the cellular degeneration, the intercellular bridges themselves enter a degenerative process. This process, involving the invagination and subsequent internalization of the bridge into the cytoplasm of one of the megalospermatocytes concerned, finally leads to disconnection of the cells and thus to the termination of the former clonal condition. Several clones of megalospermatocytes include additional cells which, while being bridge-connected to typical megalospermatocytes, exhibit a considerably different but likewise degenerative morphology. The cause of this occasionally occurring intraclonal heterogeneity of the megalospermatocyte morphology is discussed.