The purpose of the present study is to investigate the catfish brain morphology by gross anatomy, morphometric analysis in addition to light microscopy. A total of twenty African catfish (Clarias gariepinus), 30-80 cm long, with body mass 300-900gm, were used in this study. Anatomically, the brain of catfish is divided into five parts: telencephalon, mesencephalon, diencephalon, myelencephalon   and metencephalon. The most prominent parts of catfish brain are optic tectum, telencephalon, and cerebellum. The morphometric analysis of the brain of catfish revealed a large optic tectum in the mesencephalon, whilst telencephalon and the cerebellum are of medium size. The brain occupies the caudal part of the cranial cavity. The brain is slightly elongated and narrow, slightly wider in the middle portion near the mesencephalon (optic tectum), eminentia granularis and the diencephalon. The telencephalon (cerebral hemispheres) single layer formed from various neuirons which are supported by neuroglia. The optic tectum consisted of five layers stratum marginale; stratum opticum; stratum album centrale; stratum griseum centrale and stratum periventriculare. The cerebellum histologically, formed from three different layers molecular, purkinje cell and inner granular layers. The optic nerve in catfish appeared large and thick.

The present study had been established to deliver an anatomical atlas for all veterinary anatomists where various structures of the rat brain through all views are shown clearly. On the other hand, the effect of both aging and sex were put into consideration through the current study. Thirty-four apparently healthy rats of both sexes (19 males and 15 females) were used in the study. The animals were classified into four groups according to their age. Cross sections of the brain were performed to document the cerebral dimensions including the cerebral length, width, and height in addition to the transverse diameter of the thalami and the thickness of the corpus callosum. Ageing would result in a negative impact on some brain structures. However, some others had not been affected as much. Furthermore, sex of the animal presented an important role as a variant where male rats of each age group demonstrated different results than their analogous female rats. Findings of this work might be used as a tool for studying the gross morphometric changes that occurred in the rat brains due to normal aging process in either sex.