Origin of Apparent Polyploid Spermatocytes in the Mouse

Abstract

APPARENT polyploid primary Spermatocytes at diakinesis-metaphase are seen frequently in air-dried preparations from testes of mice and other mammalian species¹. Most seem to be tetraploids but some higher “polyploids” occur, including “hexaploids” and even “decaploids”. Deviation from the geometric series suggests that these cells, or at least some of them, may arise as a result of cell fusion rather than such processes as endoreduplication or the formation of restitution nuclei, which would double the chromosomes. Although apparent polyploid spermatogonia are also seen, such cells will not necessarily give rise to Spermatocytes which can reach diakinesis-metaphase. Indeed, the possibility that polyploid germ cells, spermatogonia and Spermatocytes are all an artefact of preparation arising from the spreading together of the contents of adjoining cells is not excluded on present evidence. Artefactual origin is nevertheless unlikely because of the uniformity in degree of contraction and appearance of the chromosomes or bivalents and the regularity of many of the spreads.