The present study characterized the sexual dimorphism of the cerebellum in young adult ferretsby MRI-based volumetry. Ex vivo short TR/TE MRI (typical T1-weighted parameter setting for conventional MRI) with high spatial resolution at 7-tesla were acquired from fixed cerebella of 90-day-old male (n = 5) and female (n = 5) ferrets. The cerebellar cortex, subcortical white matter and there subdivision of deep cerebellar nucleus (i.e., medial, interposed and lateral nuclei) were segmented. The cerebellar cortex further divided into the anterior vermis (lobules I-V), posterior vermis (lobules VI-VIII), caudal vermis (lobules IX and X), crus of ansiform lobule, paramedian lobule, paraflocculus and flocculus The 3D morphology and topology of those cerebellar structures were reproduced well by volume-rendered images obtained from MRI images. Volume of the whole cerebellum was significantly larger in males than in female. Within the cerebellar cortex, region-specific greater volumes in males than in females were detected in both sides of the anterior vermis, paramedian lobule and paraflocculus, and the left side of posterior vermis by two-way ANOVA and post-hoc testing. Notably, a leftward volume asymmetry was detected in the posterior vermis and paramedian lobule of males and in the flocculus of both sexes by a paired t-test. By asymmetry quotient analysis, the leftward torque asymmetry of the cerebellum was revealed in males, but not in females. The present results suggest that sexual dimorphism of the ferret cerebellum is characterized by region-related male-prominent greater volumes of the cerebellar cortex. In particular, a left-lateralized development of the posterior vermis and paramedian lobule may be involved in the leftward torque asymmetry of the male ferret cerebellum.
Ethics: approved by the Institutional Animal Care and Use Committee of Tsukuba International University.
Grant: supported by JSPS KAKENHI (23590223).