Functional morphology of the genital organs in the wild paca (Cuniculus paca) female.

Functional morphology of the genital organs is a key knowledge component for enhanced understanding of physiological patterns and for the determination of the reproductive performance in wild species. This study examines the morphology of genital organs of 133 paca females in the wild. Estimated conceptions and parturitions were mostly (83.7% and 75.5%, respectively) localized in the wet season. The pregnancy rate between 57.1% and 61.4% suggests an estimated yearly production of 1.37-1.48 parturitions and a long estimated farrowing interval of 247-266 days. Although large antral follicles were observed in all females, pregnant females had a greater number of antral follicles than females in the luteal phase. The average litter size was 1.03 foetuses per pregnant female, and mean ovulation rate was 1.33 follicles, resulting in a rate of reproductive wastage of 28.7%. The constituent active luteal tissues of the ovary were oestrous cyclic, pregnancy and accessory CL. The 50% of pregnant females in the late pregnancy stage lacked pregnancy CL, suggesting that placenta may become the mean source of progesterone during late stages of pregnancy. Results of the present study suggest that the observation of the vaginal closure membrane should not be an accurate tool for diagnosing oestrus in the paca female.