Ultrastructural Studies on the Chromatin Fibers during Spermiogenesis in the Cockroach, Blattella germanica

Abstract

Spermiogenesis in Blattella germanica was examined by electron microscopy with conventional fixation methods and PTA-staining.
Spermiogenesis was studied morphologically over the peroid of replacement of nuclear basic protein of somatic histone by sperm-specific arginine-rich protein. Before this time, 30nm chromatin fibers uncoil forming 10nm chromatin filaments. After the replacement, the chromatin recoils into 30nm chromatin fibers. The recoiled chromatin fibers are straight, unlike those before replacement of basic protein which are wavy. This difference in appearance may be due to the replacement of nuclear basic protein of somatic histone by arginine-rich protein or protamine, and differences in localization of these basic proteins in chromatin fibers.