Dasypus hybridus and Chaetophractus vellerosus, and asynchronous events with respect to the postcranium.

KRMPOTIC CM; GALLIARI F; BARBEITO CG; CARLINI AA

MAMMALIAN BIOLOGY

ELSEVIER GMBH

Año: 2012 vol. 77 p. 314 - 326

1616-5047

The integument of extant armadillos (Xenarthra, Cingulata) is a unique organ in which complex glandularsystems are associated with pilose follicles, dermal ossifications, and cornified scales. Up to date, papershave focused on neither comparative morphology of the skin (dorsal and ventral) nor chronology ofthe development of interspecific homolog structures. In order to clarify the way in which events occurduring development of the integument structures, maturity of other tissues (e.g. skeletal tissues) shouldbe considered. Therefore, we will be able to identify events that have been pre- or post-displaced duringontogenetic development. The aim of this paper is to describe in a developmental and comparativeframework the integumentary system of neonates of Dasypus hybridus and Chaetophractus vellerosus. Inorder to understand the morphology of the different integumentary structures serial histological sectionswere prepared. Staining techniques included H?E, Masson Trichrome, PAS, orcein and reticulin. To studyossification of postcranial elements, the specimens were cleared and double-stained with alcian blueand alizarin red. Determinations of ossification centers and their progress were recorded through theearly uptake of alizarin. The dorsal dermis of neonates from D. hybridus is clearly differentiated into asuperficial and deep layer, as in fetuses of Dasypus novemcinctus. In C. vellerosus, however, these layerscould not be identified. This suggests a less connective tissue differentiation in the latter species at thisstage. Osteoderms in D. hybridus are well differentiated unlike C. vellerosus where no condensations ofosteoprogenitory cells are observed. Conversely, pilose follicles and glandular tissues are less developedin D. hybridus. Regarding postcranial elements, ossification centers are less advanced in C. vellerosus thanD. hybridus, this is particularly notorious for the vertebral column, sternal, and pelvic girdle elements.Asynchronies between neonates of both species observed on integumentary and postcranial skeletaltissues could match with specific adaptive strategies related to distribution in different environments,and/or different postnatal care.