Immunohistochemical localization of prolactin cells of the pars distalis in the fetal and neonatal hamster: a light and electron microscopy study.

Using the immunoperoxidase technique, a small number of prolactin cells were first detected in the pars distalis of the hamster near developing sinusoids at 13 1/2 days gestation. Little change in number or distribution of immunoreactive cells was noted until the first few days after birth when a dramatic increase in number of immunoreactive cells was demonstrated throughout the pars distalis. Electron microscopy revealed cells in the fetal and neonatal anterior pituitary which had immunoreactive granules smaller in diameter than those seen in adult pituitary cells.