Fig. 1From: Mammalian organogenesis in deep time: tools for teaching and outreachSelected human embryos from the “Normentafel” of Keibel and Elze (1908). Approximate age of embryos based on O’Rahilly and Müller (1987): a 22 days, b 24 days, c 25 days, d 26 days, e 28 days, f 32 days, g 33 days, h–l 37–41 days, m–p around 44 days, q 47 days, r 50 days, s 52 days, t 56 days. Embryos not to scaleBack to article page