Intrauterine growth retardation (IUGR), both in human and experimental animals, can be produced by two types of factors : intrinsic and extrinsic. Intrinsic growth failure may result from congenital and/or genetic alterations. Two main categories of extrinsic growth failure have been described: a) produced by interfering with placental blood flow to fetuses; and b) produced by maternal dietary restriction. In both types, alterations of neurological functions are observed, mainly related to learning and memory.In various models of IUGR, the cerebellum is more affected than the other structures of the central nervous system,according to biochemical studies carried out by different authors.For the present work, IUGR was produced in Sprague Dawley rats according to Wigglesworth's method by ligation of one uterine artery at the 15th gestational day. The products and placentas were obtained by cæsarean section at the 21st gestational day to be weighed and studied with the light and electron microscope. The data here presented correspond to the ultrastructural study of cerebellar cortex of neonates perfused intravascularly with 2.5% buffered-glutaraldehyde, postfixed with buffered osmium tetroxide and processed for transmission electron microscopy.
