Vertebral histology in four teleostean species having different modes of axial swimming

Abstract

Histologically specific attributes of the vertebrae from fishes with four different swimming modes (i.e., anguilliform, subcarangiform, carangiform and thunniform) were studied using microradiography, natural and polarized light. Young eels (anguilliform) are structurally peculiar having 5 trabeculae in their anterior vertebae. Dorso‐central trabeculae with lateral cartilage are lacking posteriorly. Eel bone is lamellar, non‐vascular periosteal tissue and the osteocytes are arranged in rows. Other trabeculae are spongious. Anterior vertebrae in adults are also spongious. Trout (subcarangiform) have thick trabeculae peripherally. These bones are spongious and cavities are formed due to osteoclastic resorption. Secondary osteones indicate remodeling). Horse makerel (carangiform) have vertebrae that are generally spongiose, surrounded by compact bone peripherally. The vertebral cortex is parallel‐fibred, acellular bone. Vascular canals are present, apparently without orientation. Spongiosa are vascularized. Vascular primary bone are replaced by osteones. Bone remodeling gives peculiar aspect to sections. Fishes showing hyperosteosis possess compact bone rich in canals and are deprived of spongiosa. Remodeling occurred not much. Bonito showed diversity in design. Compact periphery surrounds spongious medulla. Compact bone are traversed by longitudinal and radiated canals and has osteocytes. Spongiosa has erosion bays. Remodeling confirm elevated metabolism. A distinct design for each species is clear.

Key words:

• Vertebrae ground sections
• Design
• Bone
• Zonation
• Mechanical constraints