Immunohistochemical Strept Avidin Biotin-Peroxidase Complex (SABC) three-step method was used to investigate the distribution patterns and developmental changes of GnRH and GnRHR immunopositive (GnRH-ip and GnRHR-ip) cells in the pituitary of Ji Ning Gray goats during 0-180 days of age. The results showed that GnRH-ip and GnRHR-ip cells were detected only in the pars distalis of adenohypophysis. There were no positive cells in the pars intermedia and neurohypophysis. GnRH-ip and GnRHR-ip cells were not observed in the anterior pituitary at birth day and 30 days of age. At 60 days, a number of GnRH-ip and GnRHR-ip cells were found in the anterior pituitary. GnRH-ip cells were pale brown which scattered or clustered around the sinusoid capillary; GnRHR-ip cells were brown and the cytomembrane was darker. The size and percentage of GnRH-ip and GnRHR-ip cells increased with the age growth. The numbers of GnRH-ip and GnRHR-ip cells after sexual maturity were significantly bigger than that before sexual maturity. The results above suggested that GnRH and GnRHR in the pituitary of Ji Ning Gray goats play a pivotal role in the sexual development and sexual maturity.

Key words: GnRH, GnRHR, Immunohistochemistry, Ji Ning Gray goat, Pituitary