Electron Microscope Study on Sperm Differentiation in Perinereis brevicirris (Polychaeta)

Publisher Website
Google Scholar
Abstract
Differentiation of P. brevicirris spermatozoa was examined by EM for the mode of intercellular communication at different stages of synchronized germ cell differentiation. Spermatogonia in large clusters were framed by a thin cytoplasmic envelope and appeared divided into several blocks by cytoplasmic processes. Spermatogonia in 1 block were connected to each other by desmosomes and intercellular bridges. At the spermatocyte stage, the blocks in large clusters became independent small clusters from which cells detached by meiotic divisions. These cells showed neither connection with the cytoplasmic central mass nor cytoplasmic communications, except for desmosomes, and accordingly no synchrony was observed in cell differentiation. In spermatids, the smallest group was composed of 4 cells connected by a cytoplasmic bridge. During spermiogenesis, a filamentous acrosomal rod extended through the nucleus, and nuclear condensation followed. In spermatozoa a dense material was observed in the intranuclear space near the central axis on the condensed chromatin. Mg2+-ATPase activity was found on the dense material. The functional significance of ATPase is discussed.