Ricardo Olivares P-M.; Paulina Riveros H.; Gustavo Farías R.; Julio Larenas H. & Diego Elgueda G.

The Corpus Callosum (CC) is the largest white matter commissure in the brain of placental mammals, consisting of numerous transverse fiber bundles that connect cortical areas of both cerebral hemispheres. On the other hand, stress is defined as a general response of the organism to external or internal demands, initially threatening, which consists of mobilizing physiological and psychological resources to be able to face them. Given the importance of CC in cortico-cortical connections, the aim of the present study, was to evaluate the effect of chronic prenatal immobilization stress on the macroscopic anatomy of CC in rats. Six 250g pregnant rats of the Wistar strain were used, of which three were subjected, starting on the eighth post-conception day, to movement restriction for ten days (2h/day). Subsequently, the mothers continued their gestation, delivery and lactation. At birth, litters were adjusted to six male offspring per mother (n=36), which were weaned at 21 days and slaughtered at 45-52 days of age. The brains were fixed, and later sectioned through the interhemispheric fissure and both hemispheres photographed by their medial aspect. The images were digitized and analyzed using the Scion Image® program, for the measurement of the total area, partial area (ante- rior, middle and posterior thirds, as well as posterior fifth) and callosal perimeter. Thus, prenatal stress due to immobilization significantly affected (p<0.01), the macroscopic morphology of the CC. Evidence shows a decrease in the total area, partial areas and callosal perimeter in the animals subjected to prenatal restraint, as compared to normal animals. Establishing a direct relationship between number of axons and callosal area and an inverse relationship between diameter and axonal density, what was observed may have an impact on interhemispheric transfer.

OLIVARES, P-M. R.; RIVEROS, H. P.; FARÍAS, R. G.; LARENAS, H. J. & ELGUEDA, G. D. Anatomy of corpus callosum in rats submitted to chronic prenatal stress. Int. J. Morphol., 40(2):343-347, 2022.