07. The Effects of Polypeptide Growth Factors on Oviductal Growth in the Ovariectomized Mediterranean Gecko, Hemidactylus turcicus

Abstract

Estrogens are essential for normal growth and differentiation of the vertebrate oviduct. The observation that estradiol-17β (E2) initiated little or no response in isolated mammalian uterine cells has led to the hypothesis that paracrine growth factors mediate E2-induced proliferation and differentiation of uterine cells. Several polypeptide growth factors including insulin-like growth factor I (IGF-1) and epidermal growth factor (EGF) have been implicated in this process. In a preliminary study, Mediterranean geckos, Hemidactylus turcicus, were ovariectomized. Following ovariectomy, animals were implanted with E2, IGF-1, or control pellets. After a fourteen-day treatment period oviducts were removed, fixed, embedded in paraffin, and mounted on slides. The purpose of this study is to examine the effects of E2 and growth factors, specifically IGF-1 and EGF on endometrial gland growth in these reptiles. We stained tissues from the preliminary study with hematoxylin and eosin. The glands were measured using Fiji-ImageJ software and analyzed using one-way ANOVA and Tukey post-hoc comparisons. Results indicated a significantly higher endometrial gland circumference in both E2- and IGF-1-treated animals compared to the control animals, but no significant difference was found between EGF-treated animals and control animals. In this novel research, we found that IGF-1 appears to mediate E2-induced changes in the reptilian oviduct; however, other growth factors or hormones must be involved in the process since IGF-1 alone did not elicit a full estrogenic response. Future studies will investigate additional growth factors in an attempt to construct a more complete model of the hormonal control of reptilian oviductal development.