title: Breakthroughs and blind ends.
abstract: Evolution of a through gut with an oral and an anal opening conceivably marked a breakthrough in early animal history, as basal animals have a blind ending gut with only one opening. How this occurred, and whether a through gut evolved only once or several times is a matter of debate. Perhaps the different modes by which guts develop in animal embryos that are used for the classification of animals can shed some light on this question.
authors.forename: Florian
authors.initials: F
authors.lastname: Maderspacher
mesh_terms: D000818:Animals; D005075:Biological Evolution; D041981:Gastrointestinal Tract / Q000033:anatomy & histology / Q000502:physiology; D009024:Morphogenesis