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Updated: Aug 19, 2026

Separation of Follicular Cells and Oocytes in Ovarian Follicles of Zebrafish
Published on: April 18, 2021
Human sperm can fertilize ova inside the Graafian follicles before ovulation
Zakaria M Nada1, Nashaat F Assaf, Sushil K Dubey
1IVF Center, King Fahd Specialist Hospital, Buraidah, Al-Qassim, Saudi Arabia. zmmn@hotmail.com
Objective:
To report an incidental finding of fertilization of ova inside the ovarian follicles before ovulation.
Design:
Case report.
Setting:
IVF Center, King Fahd Specialist Hospital, Buraidah, Al-Qassim, Saudi Arabia.
Patient(S):
One 31-year-old woman with 8 years of primary infertility.
Intervention(S):
Long-protocol superovulation and ovum pickup (OPU).
Main Outcome Measure(S):
The retrieved nine oocytes were incubated and followed up closely.
Result(S):
Three hours after OPU and only after decoronization of oocytes, sperm were seen attached to the zonae pellucidae of six mature oocytes. Three of them were showing signs of fertilization (two pronuclei). Neither conventional IVF nor intracytoplasmic sperm injection was done, and we decided to continue incubation and observation of all oocytes. From the nine total oocytes, fertilization was demonstrated in six with attached sperm, of which four divided. On day 2 after OPU, three embryos were transferred into the uterus.
Conclusion(S):
Human sperm can migrate and ascend through the female genital tract to get through the ovarian tissue. Moreover, under certain conditions, it can penetrate the wall of an intact ovarian follicle to reach the ovum and fertilize it just before ovulation.
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