The structure and development of the digital lamellae of lizards

Abstract

The epidermal setae and the spinules of the digital lamellae of anoline and gekkonid lizards are shed periodically along with the rest of the outer layer of the skin. These structures are developed within the lamellae prior to ecdysis. The setae are larger and more complicated than the spinules and begin their development first. The setae of Anolis start as aggregations of tonofibrils beneath the plasma membrane of the presumptive Obel-hautchen cells. These cells are arranged in rows parallel to the surface, several cell layers beneath the alpha layer of the skin. The developing setae protrude into the clear layer cells as finger-like projections, with the tonofibrils longitudinally oriented in the direction of growth. About 100 setae are formed by each Oberhautchen cells in Anolis. In late development, the clear layer

Distribution of Specific Keratin‐Associated Beta‐Proteins (Beta‐Keratins) in the Epidermis of the Lizard Anolis carolinensis Helps to Clarify the Process of Cornification in Lepidosaurians

“…The present, qualitative observation is supported by the high expression of HgGC10 in the setae of A. carolinensis (Dalla Valle et al, ) and other cysteine‐rich proteins in adhesive setae of the Tokay gecko (Hallahan et al, ). Specifically, HgGC10 and much less HgGC3 are present in the darker part of the horny material making the setae, including that of the terminal spatula, the microstructure responsible for the mechanism of adhesion (Ruibal and Ernst, ; Ernst and Ruibal, ; Autumn and Peattie, ). HgGC10 (LiAc25) is a 108 amino acid long protein with a deduced pI at 5.9, and contains lower levels of both glycine (about 13%) and cysteine (14.5%) than HgGC3.…”

“…These proteins contain a central region mostly conformed as beta‐pleated sheets (the core‐box, Alibardi and Toni, ) for which the name beta‐keratins was originally used. Forty genes and related proteins are present in A. carolinensis , and they participate to the formation of all types of scales, claws, and the climbing pad lamellae that allow this lizard to stick and climb vertical surfaces (Ruibal and Ernst, ; Ernst and Ruibal, ; Lillywhite and Maderson, ). The presence of so many proteins in the genome of this lizard indicates that different KAβPs have specialized roles in various regions of the skin.…”

Review: mapping epidermal beta-protein distribution in the lizard Anolis carolinensis shows a specific localization for the formation of scales, pads, and claws

“…Despite that their chemical-physical properties are unknown, these two proteins may impart some flexibility to the narrow beta-layer of the pad lamellae (Fig. 8c), favoring the attachment of the sticky setae to their substrate (Ruibal and Ernst 1965;Ernst and Ruibal 1966). The pad lamellae possibly contain most of the 16 glycine-cysteine-rich beta-protein detected in A. carolinensis, identified by the HGGC10 antibody (Fig.…”

“…2a). The surface of the oberhautchen forms long setae in the adhesive pad lamellae where the remaining layers are roughly similar than in the other scales (Ruibal and Ernst 1965;Ernst and Ruibal 1966). In claws, no distinction between the beta-and alpha-layers can be done, but the unguis (dorsal part) is made of a thicker corneous layer that resembles more a beta-than an alpha-layer Fig.…”

“…1i). The latter specialized scales allow to stick to the substrate, and this adhesion is utilized for climbing vertical and even upside-down surfaces (Ruibal and Ernst 1965;Ernst and Ruibal 1966;Maderson 1970).…”