Figures 3–7.

Epidermolysis bullosa simplex, integument, stillborn rhesus macaque, case 1. Figure 3. Intraepidermal clefting that transitions to complete loss of epithelium. Hematoxylin and eosin (HE). Figure 4. Cleavage sites with low numbers of basilar keratinocytes attached to the subjacent basement membrane zone. HE. Figure 5. Intraepidermal clefts with basilar keratinocytes adherent to the base of the cleft. Inset: Basilar keratinocytes adjacent to regions of cleavage have cytoplasmic vacuolation. HE. Figure 6. The intraepidermal cleft is present above the basement membrane, which stains magenta with periodic acid-Schiff reaction. Figure 7. Immunohistochemistry for cytokeratin 5. In a KRT5 insertion variant homozygous macaque (case 2), keratinocytes lack cytoplasmic immunoreactivity. Inset: Positive control (macaque lacking KRT5 mutation). Basilar keratinocytes exhibit strong, diffuse cytoplasmic immunoreactivity.