Immunofluorescent study on prolactin (PRL) synthesis in human fetal adenohypophysis

The synthesis and release of prolactin (PRL) in human fetal adenohypophysis was investigated by means of the fluorescent antibody technique. Human fetuses, ranging from the 6th to the 19th week of gestation, were collected either at hysterectomy or by legal abortion from pregnant patients with illnesses that did not affect the intrauterine development of the fetuses. Their size was measured by crown-rump length to confirm the agreement of fetal development with their gestational ages. Histologic sections of the fetal adenohypophyses were examined by differential staining methods and by an immunofluorescent procedure. In a 6-week-old fetus, PRL was observed solely on the vascular wall. However, in fetuses older than the 8th week of gestation, PRL was observed by either diffuse or granular distribution of fluorescence in the cytoplasm of both acidophilic and chromophobe cells in the adenohypophysis. Intracytoplasmic modulation of granular and diffuse fluorescence suggests the mechanism of synthesis and release of PRL in the cell which actually produces it.