These are merged digital images of sections from the pons of a P29 Gjb1−/Y//Gjc2−/− mouse and a littermate control (Gjb1+/Y//Gjc2+/−), immunostained for CD3 and CD72, T- and B-cell markers, respectively. Because the Egfp gene was “knocked into” the Gjc2- null allele, oligodendrocytes are EGFP-positive in both genotypes, T- and B-cells are present in the pons of Gjb1−/Y//Gjc2−/−(lower panels) but not in control mice (upper panels). Scale bars: 10 µm.