Embryonic and fetal morphology in the lowland paca (Cuniculus paca): A precocial hystricomorph rodent

作者：El Bizri Hani Rocha^*; Barros Monteiro Frederico Ozanan; de Andrade Rafael dos Santos; Valsecchi Joao; de Araujo Guimaraes Diva Anelie; Mayor Pedro

来源：Theriogenology, 2017, 104: 7-17.

DOI：10.1016/j.theriogenology.2017.08.004

• Reproduction
• Fetal development
• Mammals
• Survival
• Rodentia
• Amazon

In mammals, the embryonic and fetal development of a species has evolved to maximize neonatal survival. In this study, we use a sample of 132 embryos fetuses of wild lowland paca (Cuniculus paca), obtained over a period of 15 years through collaborative methods with local hunters in the Amazon to describe the intrauterine development of external and internal morphology of this Neotropical rodent. We also compare the newborn survival strategy in this species with other rodents. The crown-rump length (CRL) ranged between 0.6 and 24.6 cm. External features appeared in the following chronological order: limbs, eyelid buds, fusioried eyelids, genitalia, outer ear, tactile pelage, claws, skin, skin spots, covering pelage, teeth and open eyelids. Fetuses with CRL >19.5 cm presented all external features fully developed. The growth formula of fetal age was calculated as (3)root W = 0.082 (t - 37.25), and age was accurately associated with CRL. We described the relationship between CRL and external and internal biometry. The liver declined in proportion within the internal cavity, while the relative volume of tubular gastrointestinal organs increased significantly along the embryo/fetal development. All organs, except the heart and the thymus, had similar relative volumes in advanced fetuses and adults. Our comparison of the intrauterine development in several rodent species indicates that the paca's reproductive strategy is comparable to species that are subject to low natural predation. Given that C paca is perhaps the most hunted animal in Latin America, sustainable hunting throughout its range must take into account its relative reproductive performance.

• 出版日期2017-12