title: Origin of the notochord in the rat embryo tail.
abstract: The origin of the notochord in the rat tail was investigated on transverse serial semi-thin and ultra-thin sections of 12- and 13-day embryo tails. It was found that the notochord develops from a mass of condensed mesenchymal cells which is located ventrally to the secondary neural tube, and which subsequently splits into a) a thin cord which becomes notochord and b) a thick portion which gives rise to the tail gut. By analogy with the secondary neurulation and the secondary gut formation, one might therefore speak of a secondary notochord formation in the tail. It occurs in close relationship with the formation of the tail gut.
authors.affiliation: Institute of Histology and Embryology, Faculty of Medicine, University of Zagreb, Yugoslavia.
authors.forename: S
authors.initials: S
authors.lastname: Gajović
authors.forename: L
authors.initials: L
authors.lastname: Kostović-Knezević
authors.forename: A
authors.initials: A
authors.lastname: Svajger
mesh_terms: D000818:Animals; D004622:Embryo, Mammalian / Q000502:physiology*; D008854:Microscopy, Electron; D009672:Notochord / Q000502:physiology* / Q000648:ultrastructure; D051381:Rats; D013623:Tail / Q000196:embryology* / Q000648:ultrastructure