Revealing the long-range three-dimensional organization of tanycyte processes within the basal hypothalamus of mice

CRESPO, TOMÁS; URIARTE, MAIA; REGGIANI, PAULA; GOYA, RODOLFO G.; PERELLÓ, MARIO; DE FRANCESCO, PABLO NICOLÁS

Villa Carlos Paz, Córdoba, Argentina

Congreso; XXXIV Reunión Anual SAN 2019; 2019

Sociedad Argentina de Investigación en Neurociencias

Hypothalamictanycytes are specialized ependymal cells that line the ventral part of thethird ventricle and emit processes into the basal hypothalamus. These cells areinvolved in a host of functions, including energy homeostasis, nutrientsensing, and hormonal transport and regulation. Here, we present a novelapproach to study the anatomical distribution and fine architecture of theprocesses of the hypothalamic tanycytes in mice. The ependymal walls werelabeled, including tanycytes and their processes, using anintra-cerebroventricular injection of an adenoviral vector expressing GFP(RAd-GFP). Then, consecutive brain slices were obtained using a standard cryotomeand sequentially mounted for fluorescence volume imaging. Tanycyte morphologywith fine structural detail was readily labeled and observable in the z-stacks obtained.Continuous volume reconstructions spanning several hundreds of microns were achievedusing a software tool that we developed for the opensource package Fiji. This elastic alignment technique was able to overcome the deformationintroduced by sample slicing, by matching corresponding features in adjacentslices. With this procedure, we were able to map the distribution andorientation of tanycytic processes throughout the sampled volume, as well as toidentify and map their contacts with the hypothalamic vasculature. Thisapproach provides a valuable tool to study the complex relationship of hypothalamictanycytes and their surrounding parenchyma.