Agenesis of olfactory bulbs in 22-week fetus

Ventral view of the base of the frontal and temporal lobes of a 22-week female fetus showing agenesis of the olfactory bulbs, without even a remnant of the olfactory tracts and absence of the longitudinal olfactory grooves on either side of the midline interhemispheric fissure. The leptomeninges are well preserved, apart from an artifactual tear over the left frontal base. Microscopic examination of the entorhinal cortex (not shown) showed a deficiency of neurons (hypoplasia) and disruption of the architecture of the cortical plate. The brain was otherwise normal without other malformations. She did, however, have a complex cardiac malformation that was the cause of fetal demise, unrelated to the CNS. Karyotype was normal 46XX. (Contributed by Dr. Harvey B Sarnat.)