OVIDUCTAL STRUCTURE IN A VIVIPAROUS NEW-ZEALAND GECKO, HOPLODACTYLUS-MACULATUS

Oviductal structure is described in New Zealand's common gecko, Hoplod actylus maculatus, over four reproductive stages (early/mid-vitellogen esis, late vitellogenesis, early pregnancy, late pregnancy), using lig ht, scanning electron, and transmission electron microscopy. Five regi ons of the oviduct are recognized: infundibulum, uterine tube, isthmus , uterus, and vagina. Up to three cell types make up the luminal epith elium of the oviduct: ciliated, nonciliated, and bleb cells. The funct ion of bleb cells (seen in the infundibulum only) is unknown, but obse rvation of these cells using transmission electron microscopy suggests that they are involved in secretory activity. Mucosal glands in the u terine tube possess large numbers of secretory granules of varying ele ctron densities. Additionally, these glands appear to function as sper m storage tubules. Numerous sperm are seen in the glands during late v itellogenesis and early pregnancy. Very few uterine mucosal (shell) gl ands are seen during vitellogenesis, which is consistent with the obse rvation that only a fine shell membrane covers the egg during early pr egnancy. By late pregnancy, extraembryonic membranes lie adjacent to t he uterus allowing the formation of the omphalo- and chorioallantoic p lacentas. Maximum cell height in the luminal epithelium is seen during vitellogenesis. The maximum percentage of ciliated cells making up th e epithelial layer is seen during pregnancy. The low number of uterine mucosal glands seen in H. maculatus is a feature typical of other viv iparous reptiles described, despite independent evolutions of vivipari ty. Although oviductal structure has been described in the literature for various reptiles, several ultrastructural features seen in this st udy highlight the lack of detailed understanding of this tissue. (C) 1 997 Wiley-Liss, Inc.