The dense layer of small dark blue cells seen here below the ependyma of the lateral ventricle is the germinal matrix. The germinal matrix is a highly cellular and highly vascularized region from which cells migrate out during brain development, mainly between 22 and 30 weeks gestation. This area is highly vulnerable to birth injury and changes in blood pressure following birth. If severe and if survival occurs, the hemorrhage may organize and lead to obstructive hydrocephalus. A germinal matrix hemorrhage is shown below.