TY - JOUR TI - A Methodology for the Enzymatic Isolation of Embryonic Hypothalamus Tissue and Its Acute or Post-Culture Analysis by Multiplex Hybridisation Chain Reaction AU - Chinnaiya, Kavitha AU - Placzek, Marysia VL - 13 IS - 23 PY - 2023 DA - 2023/12/05 SP - e4898 C1 - Bio-protocol 2023;13:e4898 DO - 10.21769/BioProtoc.4898 UR - https://doi.org/10.21769/BioProtoc.4898 AB - The hypothalamus is an evolutionarily ancient part of the vertebrate ventral forebrain that integrates the dialogue between environment, peripheral body, and brain to centrally govern an array of physiologies and behaviours. Characterizing the mechanisms that control hypothalamic development illuminates both hypothalamic organization and function. Critical to the ability to unravel such mechanisms is the skill to isolate hypothalamic tissue, enabling both its acute analysis and its analysis after explant and culture. Tissue explants, in which cells develop in a manner analogous to their in vivo counterparts, are a highly effective tool to investigate the extrinsic signals and tissue-intrinsic self-organising features that drive hypothalamic development. The hypothalamus, however, is induced and patterned at neural tube stages of development, when the tissue is difficult to isolate, and its resident cells complex to define. No single molecular marker distinguishes early hypothalamic progenitor subsets from other cell types in the neural tube, and so their accurate dissection requires the simultaneous analysis of multiple proteins or mRNAs, techniques that were previously limited by antibody availability or were arduous to perform. Here, we overcome these challenges. We describe methodologies to precisely isolate early hypothalamic tissue from the embryonic chick at three distinct patterning stages and to culture hypothalamic explants in three-dimensional gels. We then describe optimised protocols for the analysis of embryos, isolated embryonic tissue, or cultured hypothalamic explants by multiplex hybridisation chain reaction. These methods can be applied to other vertebrates, including mouse, and to other tissue types.Key features• Detailed protocols for enzymatic isolation of embryonic chick hypothalamus at three patterning stages; methods can be extended to other vertebrates and tissues.• Brief methodologies for three-dimensional culture of hypothalamic tissue explants.• Optimised protocols for multiplex hybridisation chain reaction for analysis of embryos, isolated embryonic tissues, or explants.Graphical overview KW - Embryonic hypothalamus dissection KW - Enzymatic tissue dissection KW - Explant culture KW - Multiplex hybridisation chain reaction (HCR) KW - Stripping and re-probing protocol for HCR JF - Bio-protocol SN - 2331-8325 PB - Bio-protocol LLC. BIO101 - False