Embryonic lethality is not sufficient to explain hourglass-like conservation of vertebrate embryos

Table 2 Developmental stages at which perturbations were initiated

	Earliest	←	→	Latest	Evaluation of rate of lethal phenotypes
Zebrafish	Sphere	30%-epiboly	24 hpf	48 hpf	hatch
African clawed frog	st. 8	st. 11	st. 28	st. 40	st. 45
Chicken	HH5		HH16	HH20	HH25

The pharyngula periods of zebrafish, African clawed frog, and chicken are 24 hpf (hours post-fertilization), st. 28 (stage 28), and HH16 (Hamburger Hamilton stage 16), respectively

ISSN: 2041-9139