Studies on the tadpole tail. I. Structure and organization of the notochord and its covering layers in Rana catesbeiana.

Abstract

AbstractThis paper presents a detailed description of the notochord and its covering layers in the tail of the premetamorphic bullfrog (Rana catesbeiana) tadpole.In general, the notochord is a tapered, rod‐like structure composed of large vacuolated cells. It is covered by a thin basement membrane and by several thicker layers of connective tissue whose organization around the notochord differs along the length of the tail. In the proximal half of the tail the notochord and its basement membrane are followed consecutively by the notochord sheath, the elastica externa and the outer connective tissue sheath. In the distal part, however, the basement membrane is followed by the elastica interna, the notochord sheath and the outer connective tissue sheath. Toward the tip of the tail the connective tissue layers gradually become thinner and finally disappear leaving the tip of the notochord with its basement membrane lying in loose mesenchymal tissue.