The superior and inferior occipital sulci separates the three occipital gyri. Microlissencephaly is microcephaly combined with lissencephaly (smooth brain surface due to absent sulci and gyri). The lateral sulcus is one of the earliest-developing sulci of the human brain. It is generally surrounded by one or more sulci (depressions or furrows; sg. "sulcus"). Lateral to these rootlets and the anterolateral sulci are the olives. The larger sulci are usually called fissures. Emerging from the anterolateral sulci are the CN XII (hypoglossal nerve) rootlets. However, unlike alcoholics, sedative hypnotic abusers showed no evidence of widened cortical sulci. Between the labia majora and labia minora are the interlabial sulci. In some specimens lateral line sulci are retained. The serrations have no inderdenticle sulci, or grooves, in between them. First, they had lateral lines formed by the sensory sulci. Eye morphogenesis begins with the evagination, or outgrowth, of the optic grooves or sulci. Many temnospondyls also have canal-like grooves in their skulls called sensory sulci. Two prominent grooves, or sulci, run along its length.