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An ultrastructural analysis of an oocyte from an in vitro fertilization patient with repeated polyspermic
M E Schalkoff1, R D Powers, S P Oskowitz
1Boston IVF, Brookline, Massachusetts 02146, USA.
Objective:
Our goal was to determine any ultrastructural anomalies in an oocyte from a patient with a history of polyspermy.
Results:
Ultrastructural observations of the cortical ooplasm of several oocytes from each of three control patients showed a large population of intact cortical granules. Conversely, one oocyte from a patient with repeated polyspermic fertilization contained a relative paucity of granules in the cortex. Quantitative analysis of the cortices of control oocytes indicated that there were 17.02 +/- 0.52 cortical granules present per measured field of view, compared with 4.40 +/- 2.92 granules per field in the other oocyte.
Conclusions:
The presence of sufficient cortical granules is necessary for normal (monospermic) fertilization to occur. When contrasted to the cortical granule population of oocytes from several control patients, the cortex of one oocyte from the other patient showed few of these organelles. Therefore, the absence of a sufficient number of granules may have precluded normal fertilization from occurring in the eggs of this patient.