Abstract
Double-walled coated invaginations (DWCIs) of the axolemma, containing oligodendroglial cytoplasm and presumably giving rise to double-walled coated vesicles (DWCVs), are observed in the central nervous system (CNS) of adult monkey and mouse. By means of serial sections, DWCIs are clearly distinguishable from the also observable adaxonal invaginations of oligodendroglial cytoplasm. DWCIs range in diameter from 60 to 190 nm with a circular or oval cross section. Their incidence in different regions of the CNS has been determined and evidence is adduced that DWCIs occur randomly along the axolemma.