In the proximal one-third of the aesthetasc antennular region, virtually no labeling is evoked by any of the single odorants. The localization of the aesthetasc sensilla containing taurine-like immunoreactive cells in the proximal antennular region is similar to that of new sensilla and their neurons which are added during the previous molt. This suggests that newly differentiated aesthetasc chemoreceptor neurons have relatively low odor sensitivity. We can test this idea with double labeling with activity-dependent labels and BrdU labeling. We are studying how the olfactory receptor neurons in aesthetascs change during growth.
Spiny lobsters show indeterminate growth during their lives.
Associated with this growth is an addition of new sensilla, including aesthetascs, to the olfactory organ. We have shown that there is continuous turnover, including both neurogenesis and death, of aesthetascs and their ORNs, along most os the antennule. However, neurogenesis occurs mainly in the proximal part of the antennule, and cell death occurs in the more distal regions. We have used activity labeling to show that new ORNs take several weeks to months to functionally mature and become responsive to odors. Sex pheromones are known to be intraspecific communication signals in decapod crustaceans, despite there being no obvious sexual differences in the anatomy of their peripheral and central olfactory systems.