The Rhox cluster of genes (reproductive homeobox 5, Pem) was expressed predominantly from the
paternally inherited X
chromosome in mouse 8 cell embryos, morulas and blastocysts (note: the paternally-inherited allele
is usually inactivated at this stage). In contrast, expression was predominantly from the
maternally-derived allele in 7.5 dpc embryos (Kobayashi
S et al, 2006).
Maclean JA et al (2011) reported maternal
expression of Rhox1, Rhox4, Rhox5, Rhox6, Rhox9, Rhox10, Rhox12, Rhox13 in placenta and ES cells
consistent with the expected paternal inactivation of X in these tissues.