Surrounding the axis cylinder is a thick, whitish-looking layer, known as the medullary sheath, and around this is a thin covering, called the primitive sheath, or neurilemma.
"Physiology and Hygiene for Secondary Schools"
Francis M. Walters, A.M.
The whole is enclosed in a thin, delicate sheath, known as neurilemma.
"A Practical Physiology"
Albert F. Blaisdell
The deeply stained oblong nuclei indicate the nerve corpuscles within the neurilemma.
"A Practical Physiology"
Albert F. Blaisdell