Figure 1.

Is tanycyte subtype classification obsolete? (A) Tanycytes are polarized ependymoglial cells lining the basal part of the third ventricle (3V), visualized by vimentin immunostaining (white). (B) Tanycytes have been classified in four subtypes (β1, β2, α1, and α2). (C) Tanycytes (light gray) are morphologically distinguished from classical multiciliated cuboidal ependymal cells (dark gray). They send a single long radial process into the mediobasal hypothalamus including the median eminence (ME), the arcuate nucleus (ARH), the ventromedial nucleus (VMH), and the dorsomedial nucleus (DMH). Tanycytes lining the ME and vmARH are uniciliated cells, contact fenestrated vessels (red) and carry blood/brain barrier (green), whereas tanycytes lining the dmARH, the VMH and the DMH are biciliated cells, and contact neurons and blood/brain barrier vessels (pink/green). In the vmARH, vessels are permeable or not according to the energy status of the individual (red/green dashes). (D) Many genes exhibite a gradient, rather than a clear-cut distribution across tanycyte subpopulations.