Ontogenetic variation in the stratum granulosum of the epidermis of Chaetophractus vellerosus (Xenarthra, Dasypodidae) in relation to the development of cornified scales.

KRMPOTIC CM; CARLINI AA; GALLIARI F; PHAVARON P; MIGLINO MA; SCARANO AC; BARBEITO CG

ZOOLOGY

ELSEVIER GMBH

Año: 2014 vol. 117 p. 392 - 397

0944-2006

The epidermis of mammals is characterized by having a stratum granulosum that produces an orthokeratotic stratum corneum, different from the typica reptilian parakeratotic stratum. Nonetheless, some mammals show distinct degrees of parakeratosis in epidermal regions with few or no pilose follicles (e.g. the area subjacent to the cornified scales). With respect to the epidermis and the development of cornified scales in the dasypodids, previous studies support the presence of a continuous stratum granulosum without variations during ontogeny. This condition, in which the cornified scales develop without the loss of the stratum granulosum, was interpreted as primitive for eutherians. The present contribution expands knowledge of the epidermis of Chaetophractus vellerosus in distinct ontogenetic stages in order to determine whether the cornified scales show the same developmental pattern as other eutherians. The presence of a stratum granulosum in C. vellerosus neonates and its production in more advance ontogenetic stages, in direct relationship with cornified scale development, supports the hypothesis that the partial parakeratosis in the xenarthran integument is secondary, as in other eutherians, and can be interpreted as a derived character state.