Histological study of annual cycle of gonad and germ cell development of Whitmania pigra

Abstract

The reproductive system and gonad development and germ cell occurrence of Whitmania pigra have been studied by using tissue section electron microscope techniques. W. pigra has completely independent male and female reproduction system, which lasts 11 months. The development of spermary started before the development of ovary. When egg cell is only a primordial germ cell, sperm has an initially complete form. Meanwhile, sperm cells and egg cells orderly development and synchronously mature. According to the development of sperm cells and egg cells, the development of cycle of the spermary could be divided into 6 stages: proliferating stage (1-3 months of age), growing stage (4-5 months of age), resting stage (6-8 months of age), maturing stage (9 months of age), spawning stage (10 months of age) and degradation stage (11 months of age). The development of cycle of the ovary could be divided into 6 stages: forming stage (1-2 months of age), proliferating stage (3-4 months of age), growing stage (5-8 months of age), maturing stage (9 months of age), spawning stage (10 months of age) and resting stage (11 months of age). W. pigra is a synchronous hermaphrodite animal, the development of cycle of the spermary and ovary each has six stages, sperm cells and egg cells orderly development and synchronously mature.