[Stereological studies on the brain development of fetuses in cretinism endemic region after supplement of iodized salt for 10 years].

ABSTRACT

Epidemiologic reports indicated that in the cretinism endemic regions the incidence of cretinism decreased obviously after supplement of iodized salt but there still existed many cretinoid cases accompanied with mild impairment of intelligence and retardation of somatic development. This suggests that some factors other than iodine deficiency might also play an important role in the pathogenesis of cretinism. 21 brains of therapeutically aborted fetuses from cretinism endemic region after a supplement of iodized salt for ten years were studied under both light and electron microscopes. Serum T3, T4 and TSH of the fetuses and their mothers were coincidentally assayed. The brain development of fetuses from the endemic region was noticed to be still retarded as compared with those from the non-endemic region, despite that the serum hormones of the fetuses and their mothers in the endemic region showed no more significant difference from those in the non-endemic region. The retardation of the brain development could be evidenced by the increase of cellular density, decrease of the average volume of neurocytes, increase of the volume ratio between nucleus and cytoplasma per neuron, as well as decrease in number and average surface area of the mitochondria, and all of these were obtained in the cerebral cortex, hippocampus and the layer of Purkinje's cells of the cerebellum.