PROPERTIES OF THE CONNECTIVE TISSUE SHEATH OF THE COCKROACH ABDOMINAL NERVE CORD ,

Abstract

1. A method is described for removing portions of the connective tissue sheath which invests the nervous system of the cockroach, making possible studies of sheath function and of basic physiological properties of the insect neuron.2. This sheath restricts diffusion of potassium and sodium ions and of acetylcholine from the surrounding fluid to the interior of the cord.3. The ability of the sheath to restrict swelling suggests a possible osmoregulatory function.4. The functional sheath consists of an inner continuous squamous epithelial layer and an outer, almost homogeneous connective tissue layer.5. This study confirms the conclusions of Hoyle (1952, 1953) with respect to ion regulation by the insect sheath, and indicates close functional and structural parallels in the sheaths investing insect and vertebrate nervous tissue as well as in the basic properties of the nervous tissues of insects and vertebrates.