Studies of the macroscopic and microscopic morphology (hippocampus) of brain in Vencobb broiler

The aim of this study was to study the anatomy of different parts of brain and histology of hippocampus of Vencobb broiler chicken.

A 12 adult experimental birds were sacrificed by cervical dislocation. After separation of the brain, gross anatomy features were studied. Brain tissue was fixed in 10% buffered neutral formalin for 2-3 days, and then routine dehydration process in ascending grades of ethyl alcohol was done. After xylene cleaning, paraffin impregnation was prepared. Paraffin blocks were cut, and slides were stained by Harris hematoxylin and eosin. Photography was carried out both under lower (×10) and higher (×40) magnifications.

The brain structure (dorsal view) of Vencobb bird resembled the outline of a playing card symbol of a "spade." The brain subdivisions are cerebrum, cerebellum, and medulla oblongata. Cerebrum was devoid of usual convolutions (elevations), gyri, depressions (grooves), and sulci. The cerebral hemispheres were tightly apposed along a median sulcus called interhemispheric fissure and cerebrum and cerebellum were separated by a small transverse fissure. The olfactory bulb was small structures, and the pineal body was clearly visible. The optic lobes were partially hidden under cerebral hemispheres, but laterally, it was large, prominent rounded or spherical bodies of the midbrain. The hippocampal area appeared as dorso-medial protrusion. Different types of neurons were distinguished in the hippocampus were pyramidal neurons, pyramidal-like neurons, and multipolar neurons, etc. There was rich vascularization in the form of blood capillaries throughout the hippocampus.

Cerebrum was pear shaped and largest part of the brain. Cerebrum hemisphere was smooth devoid of convolutions, gyri, and depressions, but in the surface of cerebellum, there was the presence of a number of transverse depression (grooves) and sulci subdividing into many folds. Olfactory bulb was poorly developed, whereas optic lobes were rounded and large. The exact boundary line of the hippocampus was not discernable. In hippocampus histology, two categories of neuron local circuit neurons and projection neurons, high vascularization and epididymal lining of lateral ventricle were observed. Hippocampal neurons were comparatively larger without any distinct layers. The afferent neurons projected to the medium septum.