Application of Gyrification Stages of Primates to Gyrencephalic Non-primate Mammal, Ferret (Mustela putorius)

My colleagues and I have proposed four stages of the gyrification processes in primates on bases of cerebral growth and gyrification: Stage 1. Emergence of the primary sulci demarcating cerebral lobes and limbic cortex; Stage 2. Emergence of the primary sulci demarcating neocortical gyri; Stage 3. Appearance of small sulci recognized as secondary and tertiary sulci; and Stage 4. Sulcal growth. In this paper, we sought to apply our gyrification stages to the gyrencephalic non-primate mammal, ferret. The ferret cerebrum experiences the emergence of the primary sulci demarcating limbic cortex and a rough demarcation of the neocortical cortex during postnatal days 4 to 10. The gyral delineation occurs during postnatal days 10 to 21, and then, small sulci, which are not related to the gyral demarcation, emerge during postnatal days 21 to 42. I concluded that the gyrification stages in primates could be applied to the ferret cerebrum: postnatal days 4-10, 10-21, and 21-42 might be equivalent to Stage 1, 2 and 3, respectively.