Ontogenetic variation in the stratum granulosum of the epidermis ofChaetophractus vellerosus (Xenarthra, Dasypodidae) in relation to thedevelopment of cornified scales

CECILIA M. KRMPOTIC; ALFREDO A. CARLINI; FERNANDO C. GALLIARI; FAVARON PHELIPE; MIGLINO MARÍA ANGÉLICA; ALEJO C. SCARANO; CLAUDIO G. BARBEITO

ZOOLOGY

ELSEVIER GMBH

Año: 2014 vol. 117 p. 392 - 397

0944-2006

tThe epidermis of mammals is characterized by having a stratum granulosum that produces an orthok-eratotic stratum corneum, different from the typical reptilian parakeratotic stratum. Nonetheless, somemammals show distinct degrees of parakeratosis in epidermal regions with few or no pilose follicles (e.g.,areas subjacent to cornified scales). With respect to the epidermis and the development of cornified scalesin the Dasypodidae, previous studies have supported the presence of a continuous stratum granulosumwithout any variations during ontogeny. This condition, in which the cornified scales develop withouta loss of the stratum granulosum, was interpreted as primitive for eutherians. The present contributionexpands the knowledge on the epidermis of Chaetophractus vellerosus in distinct ontogenetic stages inorder to determine whether the cornified scales show the same developmental pattern as in other euthe-rians. The presence of a stratum granulosum in C. vellerosus neonates and its reduction in more advancedontogenetic stages, in direct relationship with cornified scale development, supports the hypothesis thatthe partial parakeratosis in the xenarthran integument is secondary, as in other eutherians, and can beinterpreted as a derived character state.