"DEVELOPMENTAL STUDIES ON THE SKULL OF THE TIELEOST FISH"CTENOPHARYNGODON IDELLA

Abstract

In the present work the development of the skull of the teleost fish

Ctenopharyngodon idella is described in six developmental stages (4, 5,

6, 7, 8, 1 0total length) and compared with other bony fishes.

The study was based on graphical reconstruction from stained transverse sections through the head region of the studied developmental stages.

The chondrocranium is composed, as in . all bony fishes of the

•' neurocranium and viscerocranium. The study of the development ofthe chondrocranium of Ctenopharyngodon idella has shown that the chondral neurocranium of "tropitrabic type".

In the morphological description attention has been given to the shape, position and relative size of the different constituents of the chondral skull during ontogeny. The relation of the chondral skull with the brain and main sensory organs are also considered. 1. The neurocranium is originally represented by two trab culae cranii,

parachordals, and auditory capsules. The . auditory capsule arise indpendently. The trabecula cranii appears from the beginning m continuity with the parachordals. All these elements ppears m procartilaginous state in 4mm stage. 2. The trabecula communis is formed by the fusion of the trabeculae cranii in the 5 mm larval stage where the neurocranium has chondrified. In 6 mm larval stage, the t'rabecula communis extends