The present investigation evaluates the long-term effects of programming by neonatal hypothyroidism (HPOT) on adult ovarian functions, ovarian histoarchitechture and, serum hormone profiles in the Charles foster strain of rats. Hypothyroidism was induced in neonates through lactating mothers by feeding 0.1% 6-propyl 2-thiouracil in drinking water from day 0 to day 21. The animals were screened at 22, 45 and 90 days of age in terms of body and ovary weights, ovarian histometry and serum titres of T3, T4, estradiol and progesterone. There was significant decrease in adult body and ovary weights in HPOT animals and significant decrease in ovarian volume and number of follicles. The number of antral follicles showed a significant decrement and the number of atretic follicles were high. From these findings, it can be concluded that neonatal HPOT programming has a long-term deleterious effect on adult ovarian functions in terms of growth, maturation and folliculogenesis and, alters serum titres of estradiol and progesterone as developmental plasticity changes
