Autoradiographic study of neurogenesis in the duck olfactory bulb

Neurogenesis was studied in the duck olfactory bulb by injection of tritiated thymidine into the eggs at 53 h and at the 3rd, 5th, 8th, 10th, 12th, 14th and 18th days of incubation. The large neurons appear before the small ones: the mitral cells arise between embryonic day 3 (E3) and E5, the tufted cells between E5 and E8 and the granular cells between E12 and E14. The periglomerular cells could be formed after E18. The order of appearance of this 4 main neurons of the duck olfactory bulb is the same as that in the mouse. All the neurons, except maybe for the periglomerular cells, are principally formed before the hatching of the duckling and the olfactory sense seems to have acquired most of its principal functional aptitudes at this moment.