 These pockets, or "incisures", can subdivide the myelinated axon into irregular portions.These staggered clefts also provide communication channels between layers by connecting the outer collar of cytoplasm of the Schwann cell to the deepest layer of myelin sheath.Primary incisures appear "ab initio" in myelination and always extend across the whole radial thickness of the myelin sheath but initially around only part of its circumference.