MKI67 and hydrops fetalis: The decrease in apoptosis in HF matrix cells with attached DPS suggests that some secreted components (“papilla morphogens”) [20] suppress hair matrix keratinocyte apoptosis under assay conditions; however, attached DPS did not prevent the complete loss of Ki67 + cells in the HS matrix, indicating that the secretory activity of DPS and the chosen assay conditions does not sufficiently support the extremely high proliferative activity of matrix keratinocytes.