Macro-microscopic study on the toepad of ostrich (Struthio camelus).

The ostrich foot has four toepads, two on the 3rd digit, one on the 4th digit and one at metatarso-phalangeal joint. Previous studies have not detailed the histo-morphological structure of these toepads. In this study, we have described the macroscopic and microscopic structures of the toepad of ostrich (Struthio camelus). Numerous papillae with different direction, length and thickness have been observed grossly on the ventral surface of each toepad. Histological examinations have revealed that the epidermis of the ostrich toepad, similar to other digitigrades, consists of an outer stratum corneum and an inner stratum germinativum (which is subdivided into basal, intermediate and transitional layers). The stratum corneum has several layers of flattened horny cells. The nuclei of basal cells have several mitotic figures. The cytoplasm of the stratum germinativum cells has multiple lipid droplets and multigranular bodies (in transitional cells only). Scanning electron microscopic examination revealed presence of collagen fibers in mid and deep dermis of each toepad. These fibers run parallel and connect to each other by very thin fibrils which are branched, crossed with each other in an oblique direction. Such arrangement of these collagen fibers, thin fibrils and presence of digital cushion are likely to be responsible for the protection of the underlying soft tissues and absorption of concussion.