Multiple complexes in human spermatocytes.

Multiple complexes develop during metaphase I in normal human spermatocytes. Usually they form two separate bodies about 1 micron in diameter, composed of tripartite units and a denser matrix. The tripartite units are structurally identical to the components of the central space of synaptonemal complexes (SCs). Formation of the multiple complexes occurs by shedding of SC fragments from a few chromosomal regions at prometaphase I. The combined total length of central elements in each multiple complex is 1 to 3 micron. Multiple complexes remain as cytoplasmic, perinuclear bodies during telophase I and interphase of spermatocytes II, but they were not observed during or after the second meiotic division. Although multiple complexes are initially located in the spindle, they do not show microtubular attachments and seem to be passively moved towards the periphery.