PARENT SESSION

(101) TEMPORAL AND SPATIAL EXPRESSION PATTERNS OF ANDROGEN AND HEDGEHOG SIGNALLING COMPONENTS IN MOUSE WOLFFIAN DUCT DIFFERNTIATION.

Joseph, Avenel¹, Aardema , Jorie¹, Hess, Rex¹, Yao, Humphrey¹, ¹ University of Illinois at Urbana-Champaign, Urbana, IL

ABSTRACT- The Wolffian duct (WD) is the progenitor for the male internal reproductive tract, which undergoes morphological differentiation from a simple tube-like structure into the epididymis, efferent ductules, and vas deferens. Initial formation of the WD is independent of the sex of the gonad or hormones produced in the gonads; however, later development of the WD requires Leydig cell-derived androgens, whose mechanisms of action remains unknown. In this study, we set out to identify possible signaling molecules, in addition to androgens, that could have roles in formation and maintenance of the WD in mouse embryos. Starting at embryonic day 11.5 (E11.5), when the WD undergoes morphogenesis, we found a juxtaposed pattern of sonic hedgehog (Shh), expressed in the epithelium of the WD, and its receptor Patched 1 (Ptch1), in the mesenchyme surrounding the epithelium. This expression pattern was identical in both male and female embryos, indicating a potential epithelium/mesenchymal interaction in initial formation of the WD. It is known that maintenance of the WD is dependent on androgens whose actions are mediated via the androgen receptor (AR). Consequently, we determined the normal expression pattern of AR in the WD duct and found that at E13.5, when androgen production reached its peak, nuclei of the WD epithelium became strongly positive for AR. Twenty four hours later, at E14.5, AR was found expressed in both the WD epithelium and the mesenchymal cells surrounding the WD epithelium, indicating that androgens act on both of these cell compartments. These data together demonstrated that activation of the Shh pathway preceded AR expression and Shh might be responsible for initial patterning of the WD as well as induction of the AR pathway. To investigate this plausible interaction we cultured mesonephri in the presence of cyclopamine, a potent hedgehog inhibitor, to determine its effect on AR expression in the WD. After 24 and 48 hours of culture, the hedgehog pathway indicated by Ptch1 expression was completely eradiated. However, no difference in AR expression in the mesonephros was observed. Based on these results, we propose that Shh and androgens act as two parallel pathways that play distinct roles at different stages of WD duct development. (Supported by NIEHS Toxicology Training Program Fellowship).

KEY WORDS: Wolffian duct, hedgehog, androgen receptor