The skull is opened here to reveal the "semilobar" form of holoprosencephaly, because there is a small cleft representing an attempt to separate the hemispheres. There is no gyral pattern here because this stillborn fetus was under 20 weeks gestation. Holoprosencephaly is a grave condition with little or no brain function. Holoprosencephaly can be associated with chromosomal anomalies (such as trisomy 13), with maternal diabetes mellitus, and can be seen sporadically.