Induction of agenesis of the corpus callosum by the destruction of anlage of the olfactory bulb using fetal laser surgery exo utero in mice.

It has long been discussed why some congenital anomalies were often involved with abnormalities in other organs, for example, brain anomalies accompanied by limb anomalies or cleft palate. The mechanism of combined abnormalities has been mysterious, and usually explained as pleiotropism. A combination between agenesis of the olfactory bulb and agenesis of the corpus callosum has been reported. In the present experiments, it has been suggested that non-attachment of the olfactory nerve to the rostro-ventral tip of the telencephalon blocked the induction of the olfactory bulbs from the telencephalon in genetic arhinencephalic mouse embryos. It was shown that the destruction of the olfactory bulb anlage using fetal laser surgery exo utero becomes a trigger of agenesis of the corpus callosum and irregular connection of the anterior commissure in later morphogenesis of the mouse brain. We believe that a fetal surgical experiment like this will make clear the morphogenetic mechanism of the combined abnormalities that have been previously explained as pleiotropism.