A 5‐year‐old boy presented to our clinic for a routine check‐up. Best corrected visual acuity was 20/20 and 20/60 in the right and left eyes, respectively. Cycloplegic refraction revealed +0.50 −0.50 × 179° in the right eye and −6.50 −0.75 × 171° in the left eye. The left eye had an exotropia of 14 prism diopters. Anterior segment examination was normal in both eyes. On dilated funduscopy, the ...

The permeability of K channels to various cations is studied in myelinated nerve. Ionic currents under voltage clamp are measured in Ringer solution containing tetrodotoxin and a high concentration of the test ion. Reversal potentials for current in K channels are determined and used with the Goldman-Hodgkin-Katz equation to calculate relative permeabilities. The ratios P(Tl):P(K):P(Rb):P(NHNH4...

Myelinated fibers can be demonstrated in thin unstained brain sections of freshly killed uninjected animals. With this method myelinated fibers stand out as clearly as in stained Weigert sections from formalin-fixed brains. Unstained unfixed sections can be viewed under ordinary light within minutes after death of the animal and immediately photographed for permanent records. Such sections have...

The myelin sheath enables saltatory conduction by demarcating the axon into a narrow nodal region for excitation and an extended, insulated internodal region for efficient spread of passive current. This anatomical demarcation produces a dramatic heterogeneity in ionic fluxes during excitation, a classical example being the restriction of Na influx at the node. Recent studies have revealed that...

Myelinated fibres in the human sympathetic paravertebral chain were examined histologically and in single teased fibre preparations in various age groups in subjects dying from disorders not affecting primarily the autonomic nervous system. An increase in fibre density predominantly due to an increase in the number of small fibres was found in older subjects. A correlation between internodal le...