The morphology of the mouse cerebellum.

In this description of the morphology of the mouse cerebellum, the main landmarks for subdivision were the discontinuities of the cortical sheet. In certain cerebellar sulci in the posterior lobe, the cortex is absent. Within the paramedian sulcus the cortex is interrupted rostral and caudal to the copula pyramidis. Rostrally, this discontinuity between vermis and hemisphere occupies a position corresponding to the intercrural sulcus of the ansiform lobule of other mammals. A subdivision into the simple lobule (VI and HVI), ansiform and paramedian lobule (HVII) and vermal lobule VII is proposed for this region, which accounts for the position of this cortexless area in the intercrural sulcus. Caudal to the copula pyramidis is the cortex is interrupted at the bottom of the paramedian sulcus between lobules X, IX and caudal VIII medially, and the paraflocculus and flocculus laterally. In most mammals, this area, devoid of cortex, extends much farther in the interparafloccular sulcus between the dorsal paraflocculus and the flocculus with the ventral paraflocculus. From the medullary surface of the cerebellar peduncles an area without cortex extends in between the ansiform lobule and the paraflocculus onto the copula pyramidis and the paramedian lobule. The nomenclature of the distal, foliated part of the paraflocculus in mouse, rat and rabbit is discussed.