FIGURE 2.
Insertion depth of the neonatal catheter and procedure of olfactory region-specific intranasal delivery in a C57Bl6 mouse cadaver. (A) Individual insertion depths of a neonatal catheter in the murine nose for the intranasal application at the olfactory region. The correlation between the insertion depth of the neonatal catheter and the weight of the individual animals was significant (***p < 0.0009, r 2 = 0.77, n = 10). (B–F) Sequence of the refined region-specific intranasal delivery targeting the olfactory region. (B) The mouse is kept in a supine position while the head is gently fixed with one hand. The nostril must be accessible (arrowhead) and the prepared catheter (arrowhead) kept in the other hand. (C) Note the colored pattern at the tip of the catheter as indicator of how far the catheter is inserted. (D) The catheter is carefully inserted into the nostril with a minimal angle of 20° to target the correct meatus. (E) During insertion the catheter must be rotated gently to advance it through the tight nasal cavity. (F) Once the catheter reaches the ethmoid turbinates (olfactory region) it cannot be advanced gently anymore. The colored part of the catheter is now completely introduced into the nasal cavity (arrowhead).