The Rhinencephalon of Ungulates: Gross Morphology

This chapter examines a series of ungulate brains that show a well-developed rhinencephalon in all forms, and the sense of olfaction is important to all of them, although it may be of relatively less importance in those animals with the best developed brains, as there is not a proportionate increase in therhinencephalic areas.

Abstract

This chapter examines a series of ungulate brains that show a well-developed rhinencephalon in all forms. The sense of olfaction is important to all of them, although it may be of relatively less importance in those animals with the best developed brains, as there is not a proportionate increase in the rhinencephalic areas. The olfactory bulb and stalk is generally short and stocky, although in the bovine brain there is an elongation of both. Both medial and lateral olfactory tracts can be easily identified on the ventral surface, and what appears to be an intermediate olfactory tract is present in the elephant. The lateral olfactory gyrus, or prepiriform cortex, is quite prominent in all forms. With growth in the size of the brain and an increase in fissuration of the cortex, there is a corresponding increase in the fissures present in the lateral olfactory gyrus and in the hippocampal gyrus and the uncus. The wild goats and the springbuck show the least fissuration, the elephant the most. Increases in the total size of the brain are accompanied by an increase in the thickness of the cortex of the hippocampal gyrus overlying the inferior horn of the lateral ventricle and the hippocampal formation.