Table 3.

Efficiency of chimera formation and germline colonization by ES cell lines

Source	Strain	Sex	No. of lines giving chimerism/ no. tested	Range in % of chimeras among liveborn young	No. of lines giving germline colonization/no. tested	Range in % of chimeras that transmitted	Strain of host blastocysts
Fourth-day intact blastocyst	129	Male	2/2	38–44	2/2	25–75	PO
	129	Female	2/2	10–36	1/1	100†	PO
Single-cell suspension of 5th-day epiblast	129	Male	4/4	9–24	1/4	50†	PO
			2/2	71–100	2/2	75–100	C57BL/6
Epiblast from delayed-implanting blastocyst	129	ND	5/7	40–75	3/4	33–100	MF1
Epiblast from delayed-implanting blastocyst	PO	ND	1/3	13	1/1	100	C57BL/6
Epiblast from delayed-implanting blastocyst	C57BL/6	Male	1/1	46	?/1*		MF1
Epiblast from delayed-implanting blastocyst	CBA/Ca	Male	2/4	21–33	2/2	25–50	C57BL/6
			5/5	15–100	0/2		MF1
			3/3	31–70	3/3	20–50	PO

^*Test breeding in progress. 

^†These were female chimeras; all other chimeras tested were male.