Ultrasound evaluation of fetal bone development in the collared (Pecari tajacu) and white-lipped peccary (Tayassu pecari).

The study of fetal development allows for evaluating the different strategies adopted by mammal species to maximize neonatal survival. Autonomous locomotion is fundamental for newborns to perform foraging activities and increases newborn survival from predation. In this study, we assess the gestational bone development of 53 collared (CP, Pecari tajacu) and 61 white-lipped (WLP, Tayassu pecari) peccaries, collected through the collaboration of subsistence hunters in the Amazon. The bone mineralization and biometry of the axial and appendicular skeleton were assessed by ultrasound examinations, and the timing of the main bone developmental events was calculated in relation to the total dorsal length (TDL) and the percentage of the total gestational period (GP). The first US signs of mineralization of the axial skeleton in CP and WLP were observed in fetuses with 3.4 cm (42 gestation days, 30% GPCP ) and 5.1 cm (51 gestation days, 32% GPWLP ). The early development of the appendicular skeleton was observed by the synchronic appearance of the mineralized scapula, humerus, radius, ulna, ilium, ischium, femur, tibia, and fibula at 36% GPCP (50 gestation days), and 35% GPWLP (56 gestation days). The pubis was mineralized in fetuses at 55% GPCP (75 gestation days) and 59% GPWLP (94 gestation days). The mineralization was observed in all autopod bones at 79% GPCP (109 gestation days) and 67% GPWLP (106 gestation days). All primary ossification centers in long bones of thoracic and pelvic limbs were mineralized in advanced fetuses (GPCP and GPWLP ≥75%). The mineralized patella was not observed in advanced fetuses in either species. Secondary ossification centers first appeared at the distal epiphysis of the femur in the CP (99 gestation days, 72% GPCP ) and the distal epiphysis of the radius, femur, and tibia in the WLP (106 gestation days, 67% GPWLP ). Advanced fetuses of CP and WLP presented 60% (15/25) and 68% (17/25) of the total secondary ossification centers observed present in the adult domestic pig, while newborns from the domestic pig presented 52% (13/25). The early intrauterine development of the skeletal system in both peccary species suggests a precocial development strategy, which likely correlates with neonatal ability to escape predators and reduces the dependence on parental care.

Fetal bone development in the lowland paca (Cuniculus paca, Rodentia, Cuniculidae) determined using ultrasonography.

Studying the timing of the main events of embryonic and fetal development may clarify the strategies adopted by species to maximize neonatal survival and the consequences of these events for their life history. This study describes bone development during the fetal phase of the lowland paca (Cuniculus paca), comparing it with other precocial or altricial species, and its relationship with the species' adaptive strategies. A total of 102 embryos/fetuses obtained over the course of 17 years through collaboration with local subsistence hunters in the Amazon were analyzed. Measurements of mineralization of the axial and appendicular skeletons were performed by ultrasonography using a 10-18-MHz linear transducer. The chronological order of occurrence of mineralization in relation to the total dorsal length (TDL) was: skull (TDL = 4.1 cm); vertebral bodies (TDL = 4.6 cm); scapula, humerus, radius, ulna, ilium, ischium, femur, tibia, and fibula (TDL = 6.7 cm); ribs (TDL = 7.8 cm); clavicle (TDL = 8.5 cm); metacarpi/metatarsi (TDL = 11 cm); phalanges (TDL = 15 cm); tarsus (TDL = 18 cm); patella (TDL = 23 cm); and carpus (TDL = 27.2 cm). Secondary ossification centers first appeared in the femoral distal epiphysis (TDL = 16.6 cm) and tibial proximal epiphysis (TDL = 18.4 cm). Advanced fetuses (TDL > 30 cm, 97% gestational period) presented mineralization in all primary and most secondary centers. Compared to other species, paca neonates have a well-developed skeletal system at birth, which is important for their independent postnatal locomotion. Our results may contribute to the monitoring of bone development in other wild species, helping us to understand their life history, and serving as parameters for comparisons between precocial and altricial mammals.

Functional morphology of the female genital organs in the peruvian red uakari monkey (Cacajao calvus ucayalii).

Functional morphology may provide important information that could improve methodologies for the diagnosis of the reproductive phase of females, and develop assisted breeding techniques for wildlife. This study examined features of genital organs in 19 Peruvian red uakari monkey (Cacajao calvus ucayalii) females in different reproductive stages, collected from wild animals hunted for food by rural communities in the North-eastern Peruvian Amazon, in order to provide knowledge on the reproductive physiology of this species. The observed mean ovulation rate was 1.4 follicles, and the observed maximal follicle diameter was 0.8 cm. After ovulation, the matured follicle luteinizes resulting in functional CL. In case of oocyte fertilization, the pregnancy CL grows to a maximum of 1.2 cm in diameter, and luteal volume per female decreases related to the advance of pregnancy. Pregnant females also present follicular activity until late pregnancy, but non-ovulated follicles do not undergo atretic processes and apparently transform to accessory CL, resulting in a contribution of 30% of the total luteal volume. All pregnant females delivered a single fetus at term, resulting in a rate of reproductive wastage of 20% of oocytes or embryos. The endometrium and the endometrial glands in non-pregnant females in the follicular phase show a significant increase related to the follicular growth, reaching a high proliferation in non-pregnant females in the luteal phase. The red uakari monkey showed different vaginal epithelium features in accordance with the reproductive state of the female, suggesting that vaginal cytology could be a successful methodology with which to characterize the estrous cycle of this species. The present reproductive evaluation of the Peruvian red uakari monkey provides important information that could improve the development of assisted reproductive techniques in non-human primates.

Anatomicohistological characteristics of the tubular genital organs of the female woolly monkey (Lagothrix poeppigii).

Functional morphology of the reproductive organs is a key component for the better understanding of reproductive patterns as well to maximize reproductive efficiency and to develop assisted breeding techniques adapted to wildlife. This study examined anatomical and histological characteristics of genital organs of 60 Poeppig's woolly monkey females in the wild in different reproductive stages, collected by rural hunters in the northeastern Peruvian Amazon. The endometrium, the endometrial glands, and the myometrium showed a significant increase in size related to the follicular growth. In nonpregnant females in the follicular phase, the endometrium, the endometrial glands, and the myometrium showed a significant increase related to the follicular growth. Nonpregnant females in the luteal phase had a thicker endometrium, a greater proliferation of endometrial glands, and a thicker myometrium, compared to females in the follicular phase. Nonpregnant females with small antral follicles presented high amounts of collagen beneath the endometrial epithelium, a sign of endometrial regeneration after menstruation that could be useful for the diagnosis of the reproductive phase in this species. A larger proportion of secreting cervical glands was observed in pregnant females compared to other females. The cervical mucous secretion occupied the lumen of the endocervical canal, assuring that no material could enter the uterus during gestation. The Poeppig's woolly monkey showed different vaginal epithelium features in accordance with the reproductive state of the female, suggesting that vaginal cytology could be a successful methodology with which to characterize the estrous cycle of wild primates. The present reproductive evaluation of Poeppig's woolly monkey provides important information that could improve the methodologies for the diagnosis of the reproductive phase of females, the assisted reproductive techniques in non-human primates, and could also give us opportunity for comparative studies and an insight into the evolution of animal reproductive biology, including humans.