Intrauterine growth restriction disrupts folliculogenesis in gilts: Insights into reproductive health.

Intrauterine growth restriction (IUGR) is defined as a condition in which the fetus does not reach its full growth potential with serious consequences later in life. This study evaluated, by means of histomorphometrical analysis, the follicular development in normal weight (NW) and IUGR gilts along postnatal development. Fifty pairs of littermate gilts were selected at birth and allocated into two experimental groups according to birthweight: IUGR (0.8-1.0 kg) and NW (1.4-1.7 kg). Euthanasia was performed at three stages: birth, 100 days, and 150 days of age, when body and organ weights were measured, and the ovaries fixed and processed for histomorphometrical evaluation. Follicle area of tertiary follicles from 150-day-old animals were obtained and classified according to size. IUGR newborn females presented lighter liver and brain, as well as a higher brain/liver weight ratio (P < 0.05), confirming that these females suffered intrauterine growth restriction. Moreover, IUGR gilts showed lower body weights at 100 and 150 days of age (P < 0.05), demonstrating impaired body development compared to their NW littermates. IUGR animals presented higher number of primordial follicles at 100 days and lower number of atretic follicles at 150 days (P < 0.05). IUGR females also showed a slight reduction in the number of mature follicles measuring 0.31-0.6 mm2 (P = 0.07). Collectively, IUGR impacts folliculogenesis due to the reduction in follicular recruitment and selection, suggesting that these animals may have poor reproductive performance later in life and should not be selected to enter the breeding herd.