Cover Story :
Whether cumulus cells are required for the successful vitrification of mature oocytes in cattle is controversial. Ishii et al.
re-evaluated the effects of the presence of multi-layered cumulus cells
(MCCs) on the vitrification of mature bovine oocytes (Ishii et al.,
Embryogenesis of vitrified mature bovine oocytes is improved in the
presence of multi-layered cumulus cells. pp. 95–99). In the presence of
MCCs, there was no difference between the embryonic development of fresh
and vitrified mature bovine oocytes. These results suggest that MCCs
protect mature oocytes from freezing, and promote their survival and
development after in vitro fertilization. Ishii et al.
successfully produced calves using a small number of vitrified mature
oocytes with MCCs collected from the ovaries of individual cows
post-slaughter.