Absence Of Myelin Research Articles

Long-term cultivation of dissociated neurons from embryonic chick dorsal root ganglia in the rose chamber

1. 1. A technique is described which enables the cultivation of dissociated neurons and glial cells from embryonic chick dorsal root ganglia in Rose chambers. 2. 2. Cultivated cells rapidly develop a system of communicating fibers. Neuronal perikarya are well differentiated. 3. 3. The mixed neural and non-neural cell populations undergo changes during the 2-month period of cultivation, which is divided into three stages. In the first stage (until 6–8 days), rounded neurons produce new processes. In the second stage (1–4 weeks), there is an extensive proliferation of non-neural elements and Schwann cells coinciding with a reduction of neurons. The last stage (4 weeks and older) is characterized by degeneration of fibroblasts and other elements which previously were dominant and the presence of residual neurons, often connected by nerve processes. 4. 4. Dissociated neurons were maintained in Rose chambers for more than two months. Most neurons were bipolar or multipolar. 5. 5. There was an absence of myelination despite the association of Schwann cells with axons. Peculiar phase-dense bulbs which stain for lipid were detected on axons.

LOSS OF AXIS-CYLINDERS IN SCLEROTIC PLAQUES AND SIMILAR LESIONS

CHARCOT1was apparently the first to point out the essential histologic features of sclerotic plaques: the absence of myelin, the presence of axis-cylinders, the fibrous gliosis and the perivascular infiltration with phagocytic cells. This much of his description has been copied in almost every textbook. Two of the other alterations which he clearly recognized have since appeared and disappeared repeatedly in scientific literature: the narrowing and closure of vessels and the loss of axis-cylinders, which, he wrote, persist in certain number. Chiefly, apparently, on the basis of the histology of sclerotic plaques Charcot founded the important distinction between secondary and primary degeneration of myelin. Secondary degeneration is the result of the destruction of axis-cylinders, or nerve cells. The neurofibrils disappear distal to the lesion, and the myelin then begins to disintegrate. Primary degeneration is a process which attacks almost all the myelin sheaths in an area of tissue, leaving