Materials / Reagents Required :

            10 % Neutral Buffered Formalin (NBF), Davidson’s fluid (1 litre), Modified Davidson’s fluid (1 litre), Normal saline (10 litre), 70 % Ethanol (1 litre), different sizes of scissors, forceps, scalpel, spatula, bone cutter, cardboard paper, etc.

Safety Precautions :

            Protective equipments including laboratory coats, gloves, apron, etc., should be worn during euthanasia, necropsy as well as during the preparation of the solutions.

Anatomy :

• The brain and spinal cord are covered by the meninges.  In the skull, the outermost meningeal layer, the dura mater, is doubled and forms both the periosteum of the skull and a protective covering that follows the contours of the brain surface.
• On the convex surface of the brain, the paired rostral olfactory bulbs and the smooth cerebral hemispheres separated by the deep longitudinal sagittal fissure are found. The cerebellum has folia and is divided into lateral hemispheres and a central vermis. Beneath the cerebellum are the brainstem and pons which taper into the medulla oblongata and then into the spinal cord.
• On the ventral surface of the brain, the optic chiasma is rostral to the tuber cinereum of the hypothalamus. The infundibular process by which the neurohypophysis of the pituitary gland attaches to the hypothalamus is usually disrupted when the brain is removed from the skull.
• The mammillary bodies are posterior and lateral to the tuber cinerum and rostral to the pons. The ventricular system of the brain includes the two lateral ventricles, the central third ventricle, and the caudal fourth ventricle.
• The pineal gland lies in a space between the cerebrum and the caudal colliculus. The pineal is closely apposed to the dura mater and usually remains attached to the skull when the brain is removed.

Collection of brain :

• After induction of anaesthesia/euthanasia, the fur of the animal shall be moistened with alcohol to prevent the fur from getting adhered into the tissue samples. Normal saline shall be kept ready during the necropsy to keep the lungs moist.
• The brain shall be then exteriorized by removing the calvarium. Shallow cuts shall be made with the bone cutting forceps to circumscribe the calvarium so as to prevent damage to the brain tissue. The brain shall be removed using a small blunt spatula.