This study has been done on evolution and morphology of hindbrain structure, during larvae life from 1 to 54 dph onHuso huso.It was concentrated on significant cerebellum and medulla oblongata. The cerebellum occupied the rostral part of dorsal wall offourth ventricle. The fourth ventricle was visible on 1 day old and by aging was majorly. The fourth ventricle lied on the caudallyand continued into central canal (cc) in spinal cord. Cortex of cerebellum had three layers, which were visible from 6 days old.Granular layer of corpus cerebelli, eminentia granularis, and less valvula cerebelli contained Golgi type II, and purkinje cells andobserved from 6 days old clearly. Three sulci recognized in cerebellum on 15 days old. Medulla oblongata located at the caudalpart of cerebellum and observed from 1 day old and contained eminentia granulares and crista cerebellares. Nucleuses of facialand vagal nerves were in ventral thick part of medulla oblongata. This structure, similar to cerebellum had columns of columnarcells in its gray matter. The white and gray matter, in hindbrain was visible on 1 and 3 days old, and from 6 days old the rate ofwhite matter increased. Stereological results showed that there were significantly distinctive regional differences in the volume ofdifferent parts of hindbrain represented a correlation and wasP< 0.05. Generally, inH. husolarvae from 1 to 54 days old, thevolume of hindbrain had a significant increased such that it had the largest volume in fish brain compare to other parts.

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