Avaliação ultrassonográfica do desenvolvimento ósseo fetal de caititu (Pecari tajacu, Artiodactyla, Tayassuidae).

Abstract

Ultrasonography has been presented as a useful tool for the study of fetal development and allows to evaluate the different strategies adopted by early and altricial species to maximize survival after birth. The purpose of the study was to evaluate the gestational bone development of the caititu (Pecari tajacu), to relate with adaptive strategies of the species and the consequences on its life history. Initially, the total dorsal length (TDL) and body mass of seven embryos and 46 subsistence hunting fetuses were measured. Then, the ultrasound examination was performed to identify bone mineralization and measurement of axial and appendicular skeleton bones. The skull bones (occipital, frontal and parietal) were the first to mineralize, being observed in fetuses with TDL ≥ 5.3 cm (35% of gestational period). The cervical, thoracic, lumbar and sacral spine was observed together with the ribs in fetuses with TDL ≥ 5.8 cm while the coccygeal portion was mineralized in fetuses with TDL ≥ 8.1 cm. The first bones of the appendicular skeleton were identified in fetuses with TDL ≥ 5.7 cm (36% of gestational period), in which it was possible to observe mineralization in the humeral and femur diaphysis. Mineralization of the scapula, radius, ulna, ilium, ischium, tibia and fibula was observed in fetuses with TDL ≥ 5.8 cm and metacarpal and metatarsal in fetuses with TDL ≥ 9.7 cm. The proximal, middle and distal phalanges of the thoracic and pelvic limbs were identified in fetuses with TDL ≥ 13 cm, followed by the pubis and calcaneal TDL ≥ 13.1 cm and the talus with TDL ≥ 17.8 cm. The last bones to mineralize were the carpal and distal tarsal bones with TDL ≥ 22.8 cm (79% of gestational period). Regarding epiphyseal ossification nuclei, the distal femoral nucleus was the first to be seen, appearing in fetuses from 20 cm TDL (72% of gestational period), followed by the proximal radius nucleus in fetuses from 22.4 cm and distal epiphyses of the radius and humerus from 22.8 cm TDL. In fetuses with 24.1 cm TDL it was possible to observe the proximal and distal tibial nuclei. Finally, the proximal humeral nucleus and proximal phalanges of the thoracic and pelvic limbs and distal nucleus of the ulna, metacarpal, fibula, metatarsus in TDL ≥ 29.3 cm (95% of gestation time) were observed. The other secondary ossification nuclei were not identified in the studied fetuses. Based on the results obtained, this study provides data related to intrauterine bone development of collared peccary and assists in monitoring pregnancy and estimating gestational age.