Embryonic and fetal development of the white-lipped peccary (Tayassu pecari).

The white-lipped peccary (Tayassu pecari) is an endangered large-sized Neotropical ungulate that is one of the most hunted mammals in the Amazon. Here, we used two embryos and 102 white-lipped peccary fetuses originated from animals hunted for subsistence in the Peruvian and Brazilian Amazon to describe the intrauterine development of external and internal morphology of this Neotropical ungulate. Logistic regressions were used to estimate the probability of occurrence of main external characteristics in relation to the total dorsal length (TDL), while multiple linear and non-linear regressions were conducted to assess the relationship between external and visceral biometry with TDL. External characteristics appeared in the following chronological order: limbs, differentiated genitalia and opened eyelids (≥5.1 cm TDL), fused eyelids (≥6.2 cm TDL), hooves and outer ear (≥7.9 cm TDL), dorsal gland (≥9.4 cm TDL), skin (≥11.5 cm TDL); tactile pelage (≥13.8 cm TDL), covering pelage (≥20.9 cm TDL), tooth eruption (≥26.4 cm TDL) and opened eyelids (≥27.8 cm TDL). The formula of fetal age was ∛W = 0.084 (t - 31.80), with a high linear relationship between TDL and gestational age. All external biometric parameters and absolute volume of visceral organs showed strong positive relationship with TDL. Except for the liver, we found differences in the relative volume of most visceral organs between advanced fetuses (≥34.2 cm TDL) and adults. The most important events during the intrauterine development in the white-lipped peccary show that, in contrast with the domestic pig, it is a highly precocial species producing newborns with a high fetal growth velocity which allows newborns to achieve an early autonomous functionality. Our results are relevant to improve imaging techniques and assist the reproductive and clinical management for the white-lipped peccary both in captivity and in the wild.

Fetal development of the Poeppig's woolly monkey (Lagothrix poeppigii).

The intrauterine development is an evolutionary strategy that prepares the neonate for extra-uterine life, thus providing important information on the life history of species. In this study, we described the external and internal morphology of 25 fetuses of Poeppig's woolly monkeys (Lagothrix poeppigii) by taking advantage of a 10-year participatory collection of biological samples originated from animals hunted for subsistence purposes in the Peruvian Amazon. Logistic regressions estimated the probability of occurrence of each external morphological characteristic in relation to the crown-rump length (CRL). The presence of nails, closed eyelids, differentiated genitalia and formed limbs with separation of the digits were observed in all analyzed fetuses (≥4.2 cm CRL). The other characteristics appeared in the following order: skin with epidermal pigmentation, oral and nasal mucosal pigmentation, tactile pelage and covering pelage. Although advanced fetuses (>15.8 cm CRL) showed most fetal external characteristics, they were not fully developed and no specimen showed tooth eruption or opened eyelids. The growth formula used to determine fetal age was ∛W = 0.042 (t - 45), with a high linear relationship between CRL and gestational age. All associations between the external biometry, absolute volume of internal organs and the CRL had a high coefficient of determination. Advanced fetuses and adults showed similar relative volume of thoracic and abdominal organs, except for thymus and the liver with a higher and lower relative volume, respectively. The relative volume of the tubular gastrointestinal tract and the thymus had a constant increase along fetal development, and the liver showed a significant decrease. This study describes important morphological events for understanding the gestational development in the Lagothrix genus. In addition, these results may be useful to improve imaging techniques, contributing to the in situ and ex situ reproductive management of this highly hunted species in the Amazon.

Caracterización de estadios del desarrollo embrio-fetal, vesícula coriónica y de placenta en la gata doméstica (Felis catus) mediante método ecográfico / Characterization of stages of embrio-fetal, chorionic vesicle and placenta development in the domestic cat (Felis catus) by ultrasonography

La ecografía es uno de los métodos de diagnóstico gestacional más utilizados, que permite confirmar una gestación temprana y realizar seguimientos del desarrollo embrio-fetal. En este estudio se emplearon 10 gatas gestantes, entre 10 meses a 6 años de edad, con fecha de cruza conocida. Se realizaron exámenes ecográficos seriados en los días 15 (estadio 1), 18 (estadio 2), 21 (estadio 3), 38 (estadio 4), y 45 (estadio 5) de gestación para medir parámetros biométricos. Vesícula coriónica: diámetro transversal (DTVC), diámetro longitudinal (DLVC); Placenta: grosor (GP); Feto: longitud céfalo-caudal (LCC), diámetro toraco-abdominal (DTA), diámetro cefálico (DC), tomándose un registro fotográfico de cada estadio. En el estadio 1, no se logró visualizar el embrión. En el estadio 2, el embrión se observó cercano a la pared midiendo en promedio 4,7 milímetros de LCC, el tubo endocárdico se observó funcional. En el estadio 3, se observó el cordón umbilical, pero resultó difícil distinguir los diferentes órganos, excepto el corazón, debido al movimiento causado por sus latidos. En el estadio 4, el feto adquiere movimientos, se observó órganos como el encéfalo, pulmones, el tabicamiento del corazón, diafragma, hígado, estómago, asas intestinales, vejiga y la osificación de huesos. Se observó la flexión de los miembros. En los miembros anteriores se visualizaron los dedos separados, con garras y cojinetes plantares. En el estadio 5, además de las características observadas en el estadio anterior, los riñones muestran la corteza y médula, las cámaras del corazón se visualizaron claramente. Se realizó una correlación lineal entre los parámetros biométricos estudiados y los resultados dieron valor significativo (p<0,0001) para la mayoría de éstos. Se logró caracterizar los estadios gestacionales estudiados. Siete de las diez gatas presentaron una gestación normal, mientras que una de ellas presentó en uno de sus fetos una malformación congénita y en las otras dos gatas se presentó muerte embrio-fetal.

Ultrasound is one of the most widely used methods for gestational diagnosis, allowing the detection of early pregnancy and evaluation of fetal growth and development. Ten pregnant cats (aged 10 months to-6 years) were used in this study, with known dates of mating. Serial ultrasound testings were performed on days 15th (stage 1), 18th (stage 2), 21st (stage 3), 38th (stage 4) and 45th (stage 5) of gestation, to measure biometric parameters (Chorionic vesicle: transverse diameter (DTVC), longitudinal diameter (DLVC); Placenta: thickness (GP); Fetus: cephalocaudal length (LCC), thoraco-abdominal diameter (DTA), cephalic diameter (DC). Photographic records were made at each stage. In stage 1, it was impossible to visualize the embryo. In stage 2, the embryo was observed near the wall measuring 4.7 mm on average LCC, and the endocardial tube was functioning. In stage 3, the umbilical cord was observed, but it was difficult to distinguish different organs, with the exception of the heart, which was detected by heartbeat movements. In stage 4, the fetus begins to move. Organs, such as the brain, lungs, heart septation, diaphragm, liver, stomach, bowel, bladder and bone ossification were observed. In the forelimbs, fingers apart with claws and footpads were visualized. In stage 5, in addition to the features observed in the previous stage, the kidneys show the cortex and medulla, and the heart chambers are clearly visualize. A linear correlation analysis among the biometric parameters was performed. Results were statistically significant for most parameters studied (p<0.0001). We characterized the gestational stages studied. Out of the ten cats studied, seven cats had a normal pregnancy. One cat showed one congenitally malformed fetus, and one fetal death occurred in the other two cats.