The increase in uterine oxytocin receptor (OTR)concentrations over the late luteal phase of the estrous cycle in sheep is thought to play an important role in the regulation of the cycle length by facilitating the effect of oxytocin on uterine prostaglandin release. At the end of pregnancy, a dramatic increase in the number of OTR also indicates the importance for OTR in the process of labor. In order to study the mechanisms underlying the resolution of OTR expression, the aim of this study was to obtain and
characterise OTR cDNA and OTR gene transcripts, to determine the OTR gene expression level in different tissue types, to investigate the role of exogenous steroids in
the regulation of OTR gene expression, and to develop a gene expression system for OTR protein.