Krmpotic Cecilia M, Carlini Alfredo A, Galliari Fernando C, Favaron Phelipe, Miglino María A, Scarano Alejo C, Barbeito Claudio G
Consejo Nacional de Investigaciones Científicas y Técnicas, Av. Rivadavia 1917, C1033AAJ, Buenos Aires, Argentina; División Paleontología de Vertebrados, Museo de La Plata, Paseo del Bosque S/N, 1900 La Plata, Buenos Aires, Argentina.
Consejo Nacional de Investigaciones Científicas y Técnicas, Av. Rivadavia 1917, C1033AAJ, Buenos Aires, Argentina; División Paleontología de Vertebrados, Museo de La Plata, Paseo del Bosque S/N, 1900 La Plata, Buenos Aires, Argentina.
Zoology (Jena). 2014 Dec;117(6):392-7. doi: 10.1016/j.zool.2014.06.003. Epub 2014 Aug 23.
The epidermis of mammals is characterized by having a stratum granulosum that produces an orthokeratotic stratum corneum, different from the typical reptilian parakeratotic stratum. Nonetheless, some mammals 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 scales in the Dasypodidae, previous studies have supported the presence of a continuous stratum granulosum without any variations during ontogeny. This condition, in which the cornified scales develop without a loss of the stratum granulosum, was interpreted as primitive for eutherians. The present contribution expands the knowledge on the epidermis of Chaetophractus vellerosus in distinct ontogenetic stages in order to determine whether the cornified scales show the same developmental pattern as in other eutherians. The presence of a stratum granulosum in C. vellerosus neonates and its reduction in more advanced 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.
哺乳动物的表皮特征在于具有颗粒层，该颗粒层产生正角化的角质层，这与典型的爬行动物的不全角化层不同。尽管如此，一些哺乳动物在毛囊稀少或没有毛囊的表皮区域（例如，角质化鳞片下方的区域）表现出不同程度的不全角化。关于犰狳科动物的表皮和角质化鳞片的发育，先前的研究支持存在连续的颗粒层，在个体发育过程中没有任何变化。这种角质化鳞片发育时颗粒层不消失的情况被解释为真兽类的原始特征。本研究扩展了对不同个体发育阶段的绒毛犰狳表皮的认识，以确定角质化鳞片是否显示出与其他真兽类相同的发育模式。绒毛犰狳新生儿颗粒层的存在及其在更高级个体发育阶段的减少，与角质化鳞片的发育直接相关，支持了这样的假设，即贫齿目动物体表的部分不全角化与其他真兽类一样是次生的，并且可以被解释为一种衍生的特征状态。
