“…Hereby, it is suggested that besides active migration promoting the cell distribution within the brain, a complex of tools such as bulk flow, vessel pulsation when the cells move along perivascular spaces, as well as nose-to-brain interconnection of lymphatic and cerebrospinal fluid systems contribute to their rapid entry into the brain and further distribution to different brain areas [ 43 , 44 ]. Moreover, the comparison of the cribriform plate's anatomy in humans and rodents, which is the first rigid mechanical barrier for cells on the way from the nasal epithelium to the brain [47] , [48] , [49] , allow us to suggest that the larger area and size of the cribriform plate foramina in humans would facilitate the migration of cells through these narrow openings when compared to that of rodents. Another issue that may impact transnasal delivery of cells to the brain is their long persistence, i.e.…”