Brain growth in man.

25 male brains meeting the criteria for normativity and available in serial sections suitable for morphometric studies were selected from the Yakovlev Collection. Growth parameters were calculated based on the generalized logistic function. The ideal weight is 1,313 g (SD = 41), with a half value time of 387 (SD = 26) ontogenetic days and a growth factor of 4.0 (SD = 0.5). Comparison of growth parameters derived from a sample of 161 normative male brains collected at the Department of Neuroanatomy of the Medical School in Hannover revealed an ideal weight of 1,353 g (SD = 14), a half value time of 401 (SD = 10) ontogenetic days and a growth factor of 4.0 (SD = 0.2). The minor discrepancies in the corresponding parameters reflect the small sample size and a considerable lack of developmental data of the three first postnatal decades in the material derived from the Yakovlev Collection. It was, therefore, deemed necessary to analyze these data in combination with data derived from other sources of human material. A comparison of human with animal growth parameters derived from mice, cats and tree shrews reveals differences in brain development. Histological shrinkage of the 25 male brains of the Yakovlev Collection related to fixation, embedding, and staining was assessed. Fetal brains shrank by about 75%, and adult brains by about 50%. The degree of shrinkage was inversely proportional to the age of the brain and was also characterized by individual variations of up to 20%. Therefore, shrinkage had to be corrected on an individual basis in order to determine the true growth of brain regions as reflected by morphometric analysis of histological serial sections.