CONTROL OF TERMINAL FOLLICULAR DEVELOPMENT AND MATURATION IN DOMESTICMAMMALS

Terminal follicular maturation in the ovine and the bovine species inv olves growth and differentiation processes in follicles between 1-2 mm diameter and the preovulatory stage. During this maturation, the foll icle acquires the ability to ovulate and the oocyte becomes able to be fertilized and to develop after fertilization. Selection of ovulatory follicles results from the integration of different parameters such a s the circulating levels of gonadotropins, the structure of follicular populations and the sensitivity of the hypothalamo-pituitaly axis to ovanan hormones. Differences between follicles for FSH and LH responsi veness can be amplified by paracrine intrafollicular regulations. Thes e mechanisms are probably determinant for selection of ovulatory folli cles.