Developmental abnormalities of the olfactory bulb: a comparative teratological and experimental study of the pig and...

We collected newborn pigs with facial dysmorphy. In ten animals complete unilateral or bilateral hare lip was found to be associated with agenesis, aplasia, or hypoplasia of the olfactory bulbs. In order to get insight into a possible pathomorphogenetic relation between these types of clefts, malformations of the olfactory bulbs, and the role of the derivatives of the olfactory placode, the right olfactory placode was extirpated in 180 chick embryos at stage 17-18 according to Hamburger and Hamilton. Forty of the 78 surviving embryos showed shortening and deviation of the upper bill to the right, absence of the right nasal ostium, and agenesis of the right olfactory bulb. These results provide experimental evidence that the olfactory placode induces the outgrowth of the olfactory bulb. The further suggest an involvement of the olfactory placode in the normal development of the face.