Different Morphological and Steroidogenic Patterns in Oocyte/Cumulus-Corona Cell Complexes Aspirated at in Vitro Fertilization1

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Abstract
We attempted to correlate distinct morphological data on cumulus cells to oocyte and cumulus activity. Oocyte/cumulus-corona cell complexes, which were mature 4 h after aspiration, were divided into four subgroups designated according to the type of cumulus culture morphology after 3 days of culture: type A, compact clumps; type B, partially spread clumps; type C, nonhomogeneously spread cells; and type D, homogeneously spread cells. Fertilization and cleavage rates of mature oocytes appeared to differ according to their prospectve cumulus culture morphology. Fertilization and cleavage rates were 81.5 and 62.6%, respectively, in oocyte/cumulus-corona cell complexes yielding type D cumulus cells, versus 54 and 34%, respectively, in those yielding type A cumulus cells. Basal secretion of progesterone in type A cumulus cells was 105.2 .+-. 10.3 ng/ml compared to 231.8 .+-. 22.5 ng/ml in type D cumulus cells (p < 0.001). Testosterone and estradiol secretion exhibited a significant difference as well: testosterone was 293 .+-. 10 pg/ml in type A cumulus cell versus 224 .+-. 11 pg/ml in type D cumulus cells (p < 0.001), and estradiol was 4.6 .+-. 0.4 ng/ml in type A cumulus cells versus 3.5 .+-. 0.3 ng/ml in type D cumulus cells (p < 0.05). The present study demonstrated by indirect means that oocyte/cumulus-corona cell complexes, characterized as mature a few hours after aspiration, are composed of a heterogeneous population and differ in their potential for fertilization and consequent cleavage.