P39.-Revealing the long-range three-dimensional organization of tanycyte processes within the basal hypothalamus of mice

PAULA REGGIANI; NICOLAS DE FRANCESCO; TOMAS CRESPO; RODOLFO GOYA; MAIA URIARTE; MARIO PERELLO

Villa Carlos Paz, Córdoba, Argentina

Congreso; XXXIV Reunión Anual SAN 2019; 2019

Hypothalamic tanycytes are specialized ependymal cells that line the ventral part of the third ventricle and emit processes into the basal hypothalamus. These cells are involved in a host of functions, including energy homeostasis, nutrient sensing, and hormonal transport and regulation. Here, we present a novel approach to study the anatomical distribution and fine architecture of the processes of the hypothalamic tanycytes in mice. The ependymal walls were labeled, including tanycytes and their processes, using an intra-cerebroventricular injection of an adenoviral vector expressing GFP (RAd-GFP). Then, consecutive brain slices were obtained using a standard cryotome and sequentially mounted for fluorescence volume imaging. Tanycyte morphology with fine structural detail was readily labeled and observable in the z-stacks obtained. Continuous volume reconstructions spanning several hundreds of microns were achieved using a software tool that we developed for the open source package Fiji. This elastic alignment technique was able to overcome the deformation introduced by sample slicing, by matching corresponding features in adjacent slices. With this procedure, we were able to map the distribution and orientation of tanycytic processes throughout the sampled volume, as well as to identify and map their contacts with the hypothalamic vasculature. This approach provides a valuable tool to study the complex relationship of hypothalamic tanycytes and their surrounding parenchyma.