Comparing Neurogenesis Timing Across Species
Budgie composite
Based on our morphometric analysis, we hypothesize that the telencephalon is larger in budgerigars than in quail because telencephalic neurogenesis is selectively delayed in budgerigars (telencephalic precursor cells divide more often before they differentiate). We do not yet know if this hypothesis is correct. However, it is quite obvious that the budgerigar brain, especially the budgerigar telencephalon, grows substantially after hatching (see figure; the telencephalon is to the left). Bobwhite quail brains, in contrast, grow much less after hatching. Of course, this comparison is not quite fair, because quail hatch after 23-24 days of incubation, whereas budgerigars hatch after 17-18 days (and are much less mature than quail upon hatching). Even so, preliminary data indicate that the telencephalon contains more proliferating cells in budgerigars 1 week after hatching than in quail at hatching.