Transient hypothyroidism during lactation alters the development of the corpus callosum in rats. An in vivo magnetic resonance image and electron microscopy study

Magnetic resonance imaging (MRI) data of children with late diagnosed congenital hypothyroidism and cognitive alterations such as abnormal verbal memory processing suggest altered telencephalic commissural connections. The corpus callosum (CC) is the major inter-hemispheric commissure that contra-laterally connects neocortical areas. However, in late diagnosed neonates with congenital hypothyroidism, the possible effect of early transient and chronic postnatal hypothyroidism still remains unknown. We have studied the development of the anterior, middle and posterior CC, using in vivo MRI and electron microscopy in hypothyroid and control male rats. Four groups of methimazole (MMI) treated r…