Table 1.

Generation of Chimeras Using mESCs and Mouse Blastocysts

Developmental Time	Total Mice (n)	Nkx2-1+/+		Nkx2-1+/−		Nkx2-1−/−
		Mice (n)	High-Contribution Chimeras [n (%)]	Mice (n)	High-Contribution Chimeras [n (%)]	Mice (n)	High-Contribution Chimeras [n (%)]
E13.5	33	7	3 (42.86)	17	6 (35.29)	9	8 (88.89)
E17.5	53	13	6 (46.15)	26	13 (50.00)	14	13 (92.86)
P0/P1	21	4	2 (50.00)	7	3 (42.86)	10*	9 (90.00)

Definition of abbreviations: E13.5 = Embryonic Day 13.5; E17.5 = Embryonic Day 17.5; mESC = mouse embryonic stem cell; P0/P1 = 0–24 hours after birth.

Blastocysts were obtained from crosses between Nkx2-1^+/− mice. High-contribution chimeras exhibited >10% of mESC-derived cells in the lung tissue, whereas low-contribution chimeras exhibited <10% of mESC-derived pulmonary cells.

^*All Nkx2-1^−/− chimeras died at birth.