Identification of specific relaxin-binding cells in the cervix, mammary glands, nipples, small intestine, and skin of pregnant pigs. Biol Reprod

We previously demonstrated that relaxin promotes growth and softening of the cervix and development of the mammary glands in the pregnant pig. An important aspect of understand-ing relaxin's mechanism of action in these tissues is to identify the specific cell type(s) that contains relaxin receptors, that is, to identify those cells that initiate relaxin's effects. The objective of the present study was to identify relaxin-binding cells in tis-sues known to respond to relaxin (cervix and mammary gland) as well as in tissues suspected of being responsive to relaxin (nipple, small intestine, and skin) in the pregnant pig. To accom-plish that objective we developed an in vitro modification of an immunohistochemical technique recently developed for identi-fication of relaxin-binding cells. Two groups of pregnant gilts were used: intact control (group C) and ovariectomized proges