Post-implantation development of red-rumped agouti (Dasyprocta leporina Linnaeus, 1758)

Fourteen pregnant agouti (Dasyprocta leporina Linnaeus, 1758) females at gestational ages of 30-100days and two at gestational ages of 55-100days, were studied, including 24 embryos/fetuses and two neonates (single offspring from two females). Females were euthanized and embryos/fetuses were examined, measured, and photographed. Embryos at 30days post-copulation were "C-shaped," with paddle-shaped limb buds and 10.75±0.11mm crown-rump length (CRL). In embryos at 35days post-copulation, paddle-shaped forelimbs, fin-shaped pelvic limbs, and a liver bud were evident, with 15.6±0.16mm CRL; at 45days, mouth and nostrils were evident, lower incisors were emerging, and tactile hairs could be seen near the nostrils, with 40.8±0.4mm CRL; at 55days, cranial sutures had fused, digits were totally separated and claws formation was beginning, with 58.8±0.1mm CRL; at 65days, the genital bud had differentiated, with 83±0.08mm CRL; at 85days, the body was covered with short hair, with 127.7±0.6mm CRL; and at 100days, the mature fetus had fully formed teeth and claws and an open external acoustic meatus, with 164.3±10.4mm CRL. Neonates had bristly hair and open eyes, with 179.1±0.5mm CRL. In conclusion, characteristics of the embryo/fetus during pregnancy can be used to estimate gestational age, and can be used as parameters during ultrasound examinations to help identify developmental pathologies and to test effects of nutrition, drugs, and pollution on pregnancy.