This investigation was carried out on 106 gilts and sows of Fengjing Pigs at different ages in Jinshan County,shanghai.The relative growth rate of the genital organs of the gilts was very high before 90 days of age.The average length of uterine horns of 8-month-old gilts was 108.8 ±22.4cm. Primary follicles were found in the ovaries of the gilts at birth. Multi-lagered follicles were found at 30 days of age.The first swelling and reddened appearance of vulvae in the young gilts appeared at 77.7 (48—89)days ...