Portion of tissue is a posterior to the developing notochord during tailbud extension.[TAO]

uberon

Although there is mounting evidence showing the comparability of events and formation of different nascent tissue types during gastrulation and tail development, recent work also suggests the presence of an ongoing stem cell population capable of contributing to multiple tissue types in the tail of several different vertebrates, situated in the chordoneural hinge region of the tail bud. It would seem likely that secondary signaling centers regulate the fate to be adopted by such pluripotent progenitors.[well established][VHOG]

UBERON:0007097

In mouse and chick, the derivative of the NSB (with a minor contribution from the CLE), the `chordo-neural-hinge'(CNH) (Cambray and Wilson, 2007; Catala et al., 1995; Charrier et al., 1999), contains progenitors for the ventral neural tube, somites and notochord (Cambray and Wilson, 2002; McGrew et al., 2008). The CNH is continuous with the most recently formed neural tube and notochord. By contrast, the tissue immediately caudal to the CNH exclusively produces somites in mouse and chick (McGrew et al., 2008).