. 2013 Apr 26;8(4):e62019. doi: 10.1371/journal.pone.0062019

Table 1. Inoculation of ES cells.

# of ES Cells	# of MEC's	# LacZ+ mammary outgrowths/# inoculations	# Teratomas/# inoculations
50,000	0	0/5	5/5
10,000	50,000	5/13	3/13
10,000	0	0/4	4/4
1,000	50,000	8/13	1/13
1,000	0	0/4	4/4
2^nd generation	NA	6/10	0/10

ES cells are transplanted with or without MEC's. Teratomas were produced when ES cells were inoculated alone in all cases. When ES cells were mixed with MEC's normal growth is achieved for both 10 K and 1 K ES cells, and tumor incidence was reduced. These chimeric populations grew in second transplant generations with contributions by ES cells.