Effects of human chorionic gonadotropin on echotextural attributes of the original corpus luteum in Morada Nova ewes

This study evaluated whether human chorionic gonadotropin (hCG) affects biometric, echotextural, and signs color Doppler variables of the original corpus luteum (oCL) in Morada Nova ewes. Sixty-four ewes underwent estrus synchronization with intravaginal sponges impregnated with 60 mg of medroxyprogesterone acetate for six days, with an intramuscular injection of 37.5 µg of d-cloprostenol and 200 IU of equine chorionic gonadotropin thirty-six hours before sponge removal. The ewes were subjected to natural mating and subsequently allocated to receive 300 IU of hCG (hCG group; n = 34) or 1 mL of saline solution (Control group; n = 30) intramuscularly 7.5 days after sponge removal. Biometric variables of the corpus luteum (diameter, area, volume), echotextural variables (numerical pixels values ​​and heterogeneity), and color Doppler signals (color Doppler area, color Doppler volume, and percentage of perfusion) were evaluated on days 7.5, 10.5, 13.5, and 21.5 after sponge removal. The oCL showed no differences in biometric or color Doppler signals between the hCG and control groups (P > 0.05). However, hCG increased the echotextural variables, with oCL exhibiting higher numerical pixel values ​​(88.8 ± 4.7a vs. 70.0 ± 0.8b; P = 0.0001) and heterogeneity (14.3 ± 0.6a vs. 11.5 ± 0.2b 38; P < 0.0001) compared to the control 39 oCL, respectively. Furthermore, this increased echotextural variables was also observed in pregnant females with oCL hCG when compared to pregnant females with oCL control (P < 0.05). These findings indicate that hCG enhances echotextural attributes of the oCL, suggesting functional improvement rather than structural or vascular changes during the early luteal phase.