Development of External Surfaces of Human Cerebell

Authors: Marta NowakowskaKotas Alicja Kędzia Krzysztof Dudek

Publish Date: 2014/05/16

Volume: 13, Issue: 5, Pages: 541-548

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Abstract

In the fetal period development of cerebellar lobes may proceed dissimilarly due to possible differentiated origins of the cells and diversified times of their migration to certain cerebellum regions This can cause various growth trajectories for the external surfaces of cerebellar lobes The goal of the study was to describe the development of the external surface of cerebellum lobes and fissures delineating them in the fetal period The material consisted of 101 fetuses 48 males and 53 females—crown rump length 89–229 mm corresponding to 15–28 weeks of fetal life The methods were based on anthropometric measurements and preparation techniques combined with elicited image computer analysis At the largest values of the cerebellum posterior lobe surface the most dynamic growth rate was observed in the case of the anterior lobe Among the cerebellar lobes proportional change was observed as well as a gradual increase in anterior lobe surface area and a simultaneous decrease in the surface area of the flocculonodular lobe part of the cerebellum total external surface This paper presents the different growth trajectories of cerebellar lobes and demonstrates the importance of the primary fissure as a delineating mark for two regions with different dynamics of developmentThe mechanisms of cerebellar development in the embryogenesis period are increasingly wellrecognized mainly at cellular and molecular levels Its cells originate from two proliferative zones and their migration continues until the end of the first year of life 1 Development of the cerebellum occurs with some delay in relation to the cerebrum This delay in cerebellum linear size growth is observed until the fifth month of gestation with a subsequent doubling of mass between the 19th and 35–37th weeks of fetal life 2 3 4 5 Later the cerebellum continues to develop dynamically and doubles its mass in relation to the cerebrum mass from 125 at the moment of birth up to 110–115 in adult individuals The cerebellum development rate is determined by the external granular layer cell proliferation rate This layer surface undergoes considerable augmentation due to the process of cortex enfoldment 6 7 accompanied by the development of gyruses the amount of which is estimated at 400–600 within the cerebellum external surface and in its fissures 8 The first fissures appear on the external surface in the 12th week of fetal life At first they are most distinct within the cerebellar vermis Intravital techniques ultrasound examination and MRI enable fissure visualisation with some delay in the 27th–30th and 24th–32nd week respectively 9 10 11Two fissures are especially significant because they delineate the individual lobes The primary fissure separates the anterior from the posterior lobe and the posteriolateral fissure separates the posterior lobe from the flocculonodular lobe On the basis of the literature discussing the origin of cerebellar cells it has been suggested that the primary fissure could be the boundary separating the two regions’ cells originating from the mesencephalon and from metencephalon 12 13 14 15 review in 16 Both the dynamic of development of the cerebellar lobes and the fissures in the fetal period seem to be areas of great interestDespite recent improvements in fetal MRI processing the anatomical approach to the examination of cerebellum still offers a more adequate estimation of the external surface and fissures 9 10 11 Here we investigate by means of anatomical and computerenhanced methods the external surface development of cerebellar lobes as well as the geometry of fissures delineating them in the fetal period We hypothesized that cerebellar regions would show distinct growth curves and that the shape of the fissures would change

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