Developmental Abnormalities of Dendrites of the Cerebral Cortical Neurons in Mental Retardation*

Abstract

Abstract This paper of Golgi studies describes abnormal dendritic structure and development assessed by camera lucida representation, quantitation of dendritic spines, and dendritic branch measurement in metabolic and chromosomal diseases with mental retardation, reviewing the literatures of Golgi study.Neuronal lipid storage diseases with progressive mental and motor deterioration show characteristic meganeurites between the soma and origin of the axon, and all dendrites have fewer number of branches, shorter total basal dendritic length and marked reduction of spines. Phenylketonuria and Lesch‐Nyhan syndrome also present decreased number of spines.On the other hand, children and adults with Down's syndrome show poor dendritic spine density and dendritic branchings as well as structural irregularity of spines. This poor' development of dendrites suggesting postnatal poor synaptogenesis may be related to mental retardation in children. These postnatal dendritic abnormalities may be based on genetic factors such as diminished number of cortical granular cells and extrinsic factors which include poor perception of external stimuli as noted in sensory deprivation.Thus, dendritic spine abnormalities may be correlated with mental retardation. However, we need better staining method and more sytemic study.