UNASSIGNED: In vitro maturation (IVM) in serum causes hampered expansion of porcine cumulus-oocyte complexes (COCs) due to excessive @entity5843 (A2M). This study investigated two hypotheses that could explain the effect of A2M: (i) binding of @entity4179 ( @entity4179 ) to A2M, followed by its decreased availability; and (ii) inhibition of @entity219 -dependent metalloproteases. Cumulus expansion was evaluated based on the diameter of the COCs, the proportion of COCs participating in a floating cloud and the proportion of COCs with loss of cumulus cells. The first hypothesis of decreased @entity4179 availability was tested by increasing the @entity4179 concentration (20 and 50  ng/mL vs. 10  ng/mL), but was not confirmed because cumulus expansion did not improve. To verify the second hypothesis of inhibited @entity219 -dependent metalloproteases, the effect of @entity8111 ( @entity8111 ) on cumulus expansion during IVM with and without A2M was investigated. To immuno-neutralize A2M, serum was pre-incubated with A2M antibodies. Impaired cumulus expansion because of @entity8111 could only be observed during IVM in 10% of serum with A2M antibodies. No effect of @entity8111 was observed in medium without A2M antibodies. These results indicate that A2M and @entity8111 share a common target, a @entity219 -dependent metalloprotease. Future research is directed toward the identification of the protease involved.

Hampered cumulus expansion of porcine cumulus-oocyte complexes by excessive presence of @entity5843 is likely mediated via inhibition of XXXX -dependent metalloproteases.

@entity4179 :: ('1950', 'Gene') :: ['epidermal growth factor', 'EGF'] @entity219 :: ('MESH:D015032', 'Chemical') :: ['zinc'] @entity5843 :: ('2', 'Gene') :: ['alpha2 -macroglobulin'] @entity8111 :: ('7078', 'Gene') :: ['tissue inhibitor of metalloproteases-3', 'TIMP-3']
@entity219 :: (MESH:D015032,Chemical) :: ['zinc']
