Time course of cerebellar morphological development in postnatal ferrets: Ontogenetic and comparative perspectives

Abstract

We provide the first systematic description of the morphological ontogenesis of the ferret cerebellum and compare its relative time-course to that of the rat cerebellum. Overall cerebellar size, foliation, and thickness of cortical layers were quantified and Purkinje cell morphology was characterized at 24 timepoints in ferrets from postnatal day (P)1 to P63. The ferret cerebellum was substantially larger than that of the rat and had a much longer developmental period. In ferrets, Purkinje cells were dispersed into a monolayer by P9, the formation of folia declined abruptly around P20, and the external granular layer peaked in thickness around P22 and disappeared by P56. Timepoints of corresponding relative developmental maturity of the quantified architectural features of rat and ferret cerebella were determined and their relationship was analyzed by linear regression. The time-conversion equation derived, describing the relationship between cerebellar morphogenesis in the two species, had a determination coefficient (r2) of 0.95. Conspicuously, the equation predicted with high accuracy the timing of structural changes in individual Purkinje cells in the ferret cerebellum. The conversion equation should be useful for precise quantitative translation of data between studies of ferret and rat cerebellum and for comparisons between development of motor and sensory structures and functions in ferrets. The degree of similarity in the time-courses of cerebellar development in two distantly related mammals makes explicit in quantitative terms how remarkably conserved the cerebellum is in phylogenesis. Therefore, the methodology should be applicable to precise quantitative conversions of cerebellar developmental time-courses also between other species.

A unifying model for timing of walking onset in humans and other mammals

“…In support of this notion, recent studies indicate that the relative time courses of motor development in two mammalian species may be very closely related to the relative time courses of their cerebellar development (15,16). Because the brains of different mammals appear to develop at similar rates (17), it may be assumed that the time during which the brain develops in a given species will be reflected in its adult brain mass.…”

Comparative analysis of cadherin expression and connectivity patterns in the cerebellar system of ferret and mouse

“…For example, in ferrets, postnatal cerebellar development takes notably longer than in rodents such as the rat (Clancy et al, 2001;Christensson et al, 2007), although pups are born at similar stages of cerebellar neurogenesis (Clancy et al, 2001). In carnivores and rodents, cerebellar development occurs mainly postnatally.…”

“…Labeling of the images and schematic drawings was done with Photoshop and Illustrator (Adobe Systems). With the nomenclature by Larsell (1952Larsell ( , 1953, the cerebellar lobules of ferret and mouse were numbered by roman numerals I-X (Altman and Bayer, 1997;Christensson et al, 2007). Generally, the neuroanatomical terminology of Paxinos and Watson (1998) was used.…”

A preliminary study of sleep ontogenesis in the ferret (Mustela putorius furo)

“…precocial species) [60]. Ferrets are in fact among the most altricial of placental mammals based on comparative measures of gestation [9] and neural development [9,25,37].…”