• distance segregation;
  • meiosis;
  • Mesostoma ehrenbergii;
  • non-random chromosome assortment;
  • oscillations;
  • precocious cleavage furrow


Mesostoma ehrenbergii have a unique male meiosis: their spermatocytes have three large bivalents that oscillate for 1–2 h before entering into anaphase without having formed a metaphase plate, have a precocious (‘pre-anaphase’) cleavage furrow, and have four univalents that segregate between spindle poles without physical interaction between them, that is via ‘distance segregation’. These unique and unconventional features make Mesostoma spermatocytes an ideal organism for studying the force produced by the spindle to move chromosomes, and to study cleavage furrow control and ‘distance segregation’. We review the literature on meiosis in Mesostoma spermatocytes and describe our current research with Mesostoma spermatocytes, rearing the animals in the laboratory using methods that described in our companion article [Hoang et al. (2013); Cell Biol Int].