The female genital system of Ooperipatellus decoratus (Onychophora, Peripatopsidae): An ultrastructural study

The female genital system of the oviparous peripatopsid Opperipatellus deco ratus consists of an ovary, oviducts equipped with receptacula seminis and additional pouches, uteri, and a vagina. It is examined using transmission and scanning electron microscopy. The ovary is made up of paired ovarian tu bes united anteriorly and posteriorly and differentiated into a sterile dor sal part and a fertile ventral part with exogenous oocytes. Fertilization p resumably occurs in the oviducts once the oocytes pass the receptaculum sem inis. Although the receptacula seminis have been reported to occur in juven ile. O. decoratus females only, the present study reveals that they are pre sent in adult females as well. Their wall consists of a cuboidal epithelium covered with a thin collagen-muscle layer. The additional pouches are proj ections of the oviducts facing the receptacula seminis. They are distally c losed to the haemocoel by a flattened epithelium and lack external muscle c ells. A thin collagen layer is only found proximally. The uteri are charact erized by a columnar epithelium with folded cell membranes allowing extensi on of the uteri, thus facilitating the passage of the large uterine eggs to wards the vagina. Another dominating feature of the uteri is a distally inc reasing secretory production, which probably contributes to chorion develop ment. Cilia occurring along the entire length of the uteri are considered t o assist in the transport of eggs towards the vagina. J. Morphol. 249:77-88 , 2001. (C) 2001 Wiley-Liss, Inc.