Comparative morphologic placental types in dasypodidae (Chaetophractus villosus, Cabassous chacoensis, Tolypeutes matacus and Dasypus hybridus)

Information about the morphology of placentas in armadillos is scarce, exce pt for D. novemcinctus. A comparative study of morphologic placental types in armadillos is important in order to have a comprehensive view of the pec uliar reproductive physiology in this family. The aim of this paper is to p erform a comparative analysis of the morphological features of the placenta in Chaetophractus villosus, Cabassous chacoensis, Tolypeutes matacus and D asypus hybridus in order to classify them in accordance with Grosser (1909) . The placentas were studied macroscopically and histologically (light micr oscopy in 1 mum thick sections and electron microscopy for fine structure). The macroscopic study in the 4 studied species showed a similar pear-shape d placenta homogeneously villosus in almost all the surface. The histologic al analysis showed that the 4 studied species had a hemochorial type of pla centa. This type of placenta was also found in D. novemcinctus (Dasypodidae ), but it is different from those described for other xenarthrans. Hemochor ial types of placenta have also been described in more modern mammals. Desp ite the many primitive features of the armadillos and the different anatomi cal and physiological features between the genuses of dasypodids, all the s tudied species share this structural type of placenta.