Ultrastructural observations on the platelets of the Arabian tahr (Hemitragus jayakari)

A study of platelets in the armadillochaetophractus villosus(xenarthra, dasypodidae)

Nothing is known about haemostasis in Xenarthra, a widely distributed Order of American mammalians. Chaetophractus villosus, a member of the Dasypodidae family of this group, which is easily adapted to captivity, is of growing interest for biomedical research. In this work, we studied platelet number, MPV, ultrastructure of the platelets by SEM and TEM, and aggregation responses to ADP and ristocetin in this species. Blood samples were obtained by cardiac puncture in 20 anaesthetised animals. Platelet count and MPV were evaluated at the beginning and at the end of a 3-year experimental period, to detect possible variations related to time of captivity. SEM and TEM were done by routine methods adapted to the material, and aggregation response to ADP and ristocetin were evaluated by the Born method. The parameters studied did not show any sex-related differences, nor did the platelet count change during captivity. Nevertheless, MPV decreased during this period. Platelets were ultrastructurally similar to those of other mammals and human beings and responded to proven agonists. Data provided in this study will contribute to the understanding of the haemostatic process in this species.