Prevention of lesioning-induced precocious puberty in female rats by neonatal implantation of fetal preoptic tissue.

Damage to the medial preoptic area (MPOA) was produced in one-day-old female rats by bilateral electrolytic lesions or by aspiration of preoptic tissue. Both procedures resulted in similar advancement of vaginal opening and the first ovulation. A further group of rats was lesioned or aspirated in the MPOA and immediately bilaterally implanted with medial preoptic tissue collected by the puncture method from 17-19-day-old female rat fetuses. After autopsy, tissue destruction and implants located in the MPOA could be identified in 5 females that showed significantly later onset of puberty than both the lesioned or aspirated and the untreated controls. The findings suggest that the elimination of neurones and not a stimulatory effect of electrolytic lesions on GnRH secretion is responsible for the acceleration of sexual maturation recorded after lesioning of the MPOA. Possible reasons for the failure to identify the grafts in most of the implanted females are discussed.