Table 2.

Three hypothetical sources of influence, reconciling the H19 methylation data on EG cells derived from 11.5 dpc PGCs (4) with the data on 15.5 and 16.5 dpc PGCs from the present article (Table 1)

Cells	Phenotype	Chromosome constitution	Tissue environment	X chromosome	Y chromosome	Resultant
PGCs	Males	XX	↑	↓	↑	Methylation
		XY	↑	↓↓		Less methylation
	Females	XY	↓	↓	↑	Hypomethylation
		XX	↓	↓↓		Hypomethylation
EG cells	Males	XY		↓	↑	Methylation
		XX		↓↓		Hypomethylation
	Females	XY		↓	↑	Methylation
		XX		↓↓		Hypomethylation

Upward and downward arrows indicate positive and negative influences, respectively, on site-specific methylation.