Ontogeny of LH receptor gene expression in the pig reproductive tract

In view of the recently documented expression of the LH receptor gene in se veral nongonadal reproductive tissues, the aim of this study was to analyse further the ontogeny of expression of this gene in the pig reproductive tr act in fetal and neonatal life. RT-PCR was used to investigate the expressi on of the extracellular and transmembrane receptor domains, and to identify the time of onset of transcription of the full-length LH receptor mRNA and its shorter splice variants. Expression of the LH receptor gene was first detected around day 30 of fetal life in both ovary and testis, coinciding w ith morphological differentiation. The pattern of expression of LH receptor splice variants did not change during postnatal gonadal maturation. Expres sion of the LH receptor gene in the pig non-gonadal reproductive tract star ted during fetal life and continued during sexual maturation. A novel pig L H receptor spliced variant, lacking exon 10, was detected for the first tim e. The transmembrane receptor domain was expressed in fetal tissues, but no t in neonatal control tissues. On the basis of the transmembrane domain of the LH receptor mRNA, it is concluded that the ovary and extragonadal tissu es of the pig reproductive tract, like the pig testis, synthesize functiona l LH receptors during fetal life. The presence of LH receptor mRNA in extra gonadal reproductive tissues indicates that LH is involved in the control a nd regulation of reproductive tract maturation.