Duration of synthesis of only alphakeratin of skin-rapid cell turnover (the renewal phase) in Sphenodon & all lizards & snakes so far studied

Value 14 days
Organism Reptiles
Reference Alibardi L. Adaptation to the land: The skin of reptiles in comparison to that of amphibians and endotherm amniotes. J Exp Zool B Mol Dev Evol. 2003 Aug 15 298(1):12-41. DOI: 10.1002/jez.b.24 p.21 left column top paragraphPubMed ID12949767
Comments P.21 left column top paragraph: "Differently from the previous reptilian groups, in lepidosaurians (Sphenodon, lizards, and snakes), the deposition of beta-keratin over alpha-keratin is cyclical and seasonal (Maderson et al., ’98 Alibardi and Maderson, 2003a). The corneous layer is composed by a thin beta-layer (hard keratin) followed by an alpha-keratin layer (soft keratin). This composite stratum corneum confers deformable characteristics to the pliable skin, typical of these agile and light reptiles. Betakeratin is deposited over alpha-keratin in only three to seven layers of (beta) cells, after which its synthesis stops and only the synthesis of alphakeratin continues. This phase of rapid cell turnover (the renewal phase) occupies 14 days in all species so far studied, after which the external epidermis (i.e., outer epidermal generation) separates from the inner portion (i.e., inner epidermal generation)."
Entered by Uri M
ID 113170