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Tanycytes: Morphology and Functions: A Review

1985; Elsevier BV; Linguagem: Inglês

10.1016/s0074-7696(08)60596-3

2163-5854

J Flament-Durand, Jean‐Pierre Brion,

Neonatal and fetal brain pathology

The chapter presents a review of the morphology and functions of tanycytes. The name "tanycyte," derived from the Greek word "tanus," which means "elongated," was chosen to stress the shape of these bipolar cells, in relation at their apical pole with the infundibular recess of the third ventricle and, at their distal pole, with the portal vessels of the median eminence and the floor of the brain. The morphology of tanycytes has been thoroughly explored by means of photonic observations as well as by transmission (TEM) and scanning (SEM) electron microscopy. The review of the chapter will be restricted to the tanycytes lining the ventral region of the third ventricle in mammals, thus, excluding the study of similar cells lining the circumventricular organs (subfornical organ, subcommissural organ, organum vasculosum of the lamina terminalis), the aqueduct, and the floor of the fourth ventricle. The possible functions of the tanycytes will also be reviewed. The Golgi impregnation has been used by several authors to study the morphology of the tanycytes in mammals. Because of the thickness of the sections impregnated by this method, it is possible in favorable incidences to follow the entire length of these elongated cells, allowing a dissection in situ. This method demonstrates two main types of tanycytes according to their location and their morphology. The ventral tanycytes are located on the floor and lower third of the infundibular recess. Dorsal tanycytes have a longer tail process, starting from the base of the tanycyte and arching ventrolaterally in the neuropil of the arcuate nucleus. Glycerophosphate dehydrogenase (GPDH), lactic dehydrogenase (LDH), and glucosed-phosphate dehydrogenase (G6PD) are more active in the perikaryons of β tanycytes as compared to α.