Endomysium, connective tissue containing collagen fibres that surrounds the individual muscle fibres. The endomysium is responsible for the tensile strength of the muscle. Many muscle fibres form a primary bundle (diameter = 1 mm) .
The primary bundle is also surrounded by a connective tissue, the perimysium.
Several primary bundles = secondary bundles form the macroscopically visible fibres of the muscle. The complete muscle strand is surrounded by a fascia, which has a loose connective tissue, the epimysium, on the inner side.
Antibodies against endomysium can be detected in gluten-sensitive enteropathy (see also celiac disease). IgA antibodies were first detected using a monkey esophagus (Jäger L et al. 2001). Therefore, they were also called primate reticulin antibodies. The crucial antigen in the endomysium is tissue transglutaminase (tGA). Under the action of tGA, an epitope is formed by deamidation of the gluten in gliadin, which can be bound to a particular extent by the DQ2-DQ8-positive cells.