Multinuclearity of germ cells in the senescent human testis originates from a process of cell-cell fusion.
Multinucleated spermatogonia in the senescent human seminiferous epithelium are ultrastructurally characterized. Due to their rare occurrence, only the method of re-sectioning and EM-analysing of selected semithin sections allowed the targeted studying of a sufficiently large number of these cells and the direct and detailed documentation of the rapid process of cell-cell fusion responsible for the formation of multinuclearity. This process includes broad cellular apposition, formation of large areas of membrane junctions, multiple membrane fusion events resulting in small cytoplasmic connections, and subsequent gradual cytoplasmic confluence of the cells involved. As a result of this process, pre-existing intercellular bridges between fusing cells of a germ cell clone attain a freely intracellular position. Multinucleated germ cells in the senescent human testis thus represent a new example of a cell-cell fusion under pathological conditions.
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Institute of Anatomy, University of Bonn, Federal Republic of Germany.
D000368:Aged; D000369:Aged, 80 and over; D000375:Aging; D002459:Cell Fusion; D015726:Giant Cells / Q000648:ultrastructure; D006801:Humans; D008297:Male; D008854:Microscopy, Electron; D012670:Seminiferous Epithelium / Q000166:cytology*; D013093:Spermatogonia / Q000648:ultrastructure*; D013737:Testis / Q000166:cytology*