Distribution of P2X receptor subtypes in the rat female reproductive tractat late pro-oestrus/early oestrus

Using immunohistochemistry techniques, we have examined the female reproduc tive organs of the rat in late pro-oestrus/early oestrus for the presence o f purine nucleotide P2X(1-7) receptors. In contrast to the male genital org ans and the urinary tract, P2X(1) receptors were present weakly, if at all, on smooth muscle membranes, except in blood vessels, whereas P2X(2) immuno reactivity in smooth muscle was present in ovary and uterus as well as in b lood vessels. Neither P2X(1) nor P2X(2) receptors were present in fallopian tubes. P2X(5) receptors were seen in the differentiating cell layers of th e stratified squamous vaginal epithelium and also in the very early stages of ovarian follicular development; P2X(6) receptors were present in seconda ry follicles. P2X(7) receptors, markers for programmed cell death, were pre sent in the keratinised vaginal epithelium and also in the exfoliating supe rficial endometrial cells. The possible biological significance of these si gnalling molecules in the female reproductive tract is discussed.