Fig. 1
From: Advances in intranasal application of stem cells in the treatment of central nervous system diseases
Possible brain-entry routes of substances by INA (in rodents as an example). After intranasal injection into the nasal cavity of rodents, drugs or cells are transported via the intracellular and/or paracellular pathways, and pass through the olfactory epithelium and reach the olfactory bulb along the olfactory nerve, or pass through the respiratory epithelium to reach the olfactory bulb/brainstem along the ophthalmic or maxillary branches of the trigeminal nerve. After reaching the CNS, drugs or cells are further distributed in the brain through the cerebrospinal fluid and/or perivascular spaces