Toe-pad morphology in White's tree frog, Litoria caerulea (Family Hylidae)

Abstract

The aim of this study was to find any structural differences between the digital pads of forelimbs and hind limbs as well as more careful investigation of the internal and external structures of the toe-pad. In this study, pad morphology and cytology in Litoria caerulea is described using SEM, TEM and light microscopy. At the gross anatomical level, toe-pads in hind limbs were subdivided into medial and lateral parts by two large grooves. Semi-thin sections also showed that the toe-pad epidermis in hind limbs consisted of four layers with a cuboidal outermost layer, while the epidermis of forelimbs consisted of 3 layers with a columnar outermost layer. SEM study revealed two basic shapes of epidermal cells arranged very regularly across the surface of the pad: pentagonal and hexagonal. The pentagonal mainly occupied the most distal part of the toe. Three types of mucous-secreting pores were also seen in between the epithelial cells.