DEVELOPMENT OF SKELETAL SYSTEM OF MEGALOBRAMA AMBLYCEPHALA(PISCES: CYPRINIDAE)

The present paper deals with the development of skeletal system of Megalobrama amblycephala, including the development of neurocranium, splanchnocranium, vertebrae, Weberian apparatus and appendicular skeleton. The skeletal development was observed with transparented and stained samples. The morphological characters and process of the skeletal development were described and drawn.The total length is 4.0 mm when the larva has just hatched. The prelarvae stage, from just hatched to yolk sac completely absorbed(4.0-7.0 mm), has a few cartilages. The postlarvae stage, from yolk sac completely absorbed to the occurrence of pterygiophores of ventral fin(7-24 mm), is the important period in skeletal development, for many of the skull and appendicular skeletons are ossified and the vertebrae are completely formed. The juvenile stage, from the ossification of fin rays of ventral fin to the appearance of scales on both sides of the body(24-38 mm), is characterized by most of the skull cartilages being ossified. The young stage, from scales covering the entire body to the period before maturity(above 38 ram), has the skeleton all developed so that the characters of skeletal system is the same as the adult.Weberian apparatus is formed from the specialization of part of the first three vertebrae.There are five to six interspines found between fourth and" ninth neural spines.According to the different process of skeletal development, each bone can be determined whether it is dermal bone or cartilaginous bone.