Kieselalge. Bildung von vier oder acht beschalten Spermatogonien durch zwei oder drei Differenzierungsteilungen in der Mutterzelle, Bildung von vierkernigen Spermatozyten durch zwei meiotische Teilungen (keine Zytokinese), Differenzierung der eingeißeligen, plastidenfreien Spermien. Mit Zeitraffung.

The formation of male gametes of the Stephanopyxis turris is initiated by two or three differentiating divisions. From this, four or eight spermatogoni with shells emerge, enclosed in the mother cell. These enter into meiosis as spermatocytes. Since there is no cytocinesis, thw two meiotic divisions yield spermatocytes with four nuclei. Sperms with one flagellum and without plastides are formed. The main part of the plasma of the spermatocytes as well as all plastides are left behind in residual bodies.