IMMUNOHISTOCHEMICAL DETECTION OF MYELIN BASIC-PROTEIN IS A SENSITIVE MARKER OF MYELINATION IN 2ND TRIMESTER HUMAN FETAL SPINAL-CORD

The Luxol fast blue (LFB) technique is widely used for the assessment of myelination. Lectin histochemistry using peanut agglutinin (PNA) ha s also been employed for this purpose. Recently, immunohistochemical m ethods using antibodies to several myelin-related proteins have been a dopted to study myelination in humans. However, the relative sensitivi ties of these different methods for the detection of early myelination in the human fetal central nervous system have not been determined. V ibratome sections of cervical spinal cord from 15 human abortuses rang ing in age from 15 to 24 gestational weeks (GW) were probed with immun ohistochemical methods using antibodies to myelin basic protein (MBP), 2',3'-cyclic nucleotide 3'-phosphodiesterase (CNPase), and myelin-ass ociated glycoprotein (MAG). In addition, LFB and PNA histochemistry wa s employed. The degree of myelination observed in immunohistochemicall y stained sections was compared to that found in corresponding LFB- an d PNA-stained paraffin-embedded tissues. The intensity of myelination was graded by two observers on a scale of 0 (none), + 1 (mild), + 2 (m oderate), and + 3 (marked). At all ages examined, the MBP immunohistoc hemical method revealed more myelin than LFB or MAG staining. CNPase c ould not be reliably detected until after 18 GW. Peanut agglutinin sta ined myelin, but subpial astrocytes and the intervening neuropil were also stained. These results suggest that MBP is a more sensitive marke r for early human fetal myelination than CNPase, MAG, PNA or LFB.