“…Several events in early development have been shown to be temperature dependent, e.g. oocyte maturation and viability (Lenz et al, 1983;Katska & Smorag, 1985;Moor & Crosby, 1985;Syms et al, 1985;Barros et al, 1986;Morstin & Katska, 1986), post-fusion events (Hirao & Yanagimachi, 1978b) and cell proliferation and viability of cleavage stages (Chang, 1947(Chang, , 1948aHafez, 1963Hafez, , 1969Whittingham & Wales, 1969) and blastocysts (Chang, 1950). Most of these investigations, however, focussed on storage and cryo¬ preservation of oocytes and embryos (for review see Wilmut, 1986).…”