Document Type : Original Articles
Authors
1
Department of Theriogenology, Faculty of Veterinary Medicine, University of Tehran, Tehran, Iran
2
Department of Stem Cells and Developmental Biology, Cell Science Research Center, Royan Institute for Stem Cell Biology and Technology, ACECR, Tehran, Iran
3
Department of Molecular Genetics, Faculty of Biological Sciences, Tarbiat Modares University, Tehran, Iran
4
Department of Cell Engineering, Cell Science Research Center, Royan Institute for Stem Cell Biology and Technology, ACECR, Tehran, Iran
5
Department of Embryology, Reproductive Biomedicine Research Center, Royan Institute for Reproductive Biomedicine, ACECR, Tehran, Iran
6
Department of Theriogenology, Faculty of Veterinary Medicine, University of Tehran
Abstract
Background: In vitro culture of one-day-old mouse ovary can serve as a valuable model for studying the biology of ovarian ontogeny. Although some progress has been made over recent years in refinement of this culture system, it still needs more modifications to enable production of large preantral follicles for further assisted reproductive techniques. Yet examination of any new modification warrants more extensive knowledge on the dynamics of ovarian follicles over the course of in vitro culture.
Objectives: The present study was conducted to obtain a more comprehensive understanding about development of one-day-old mouse ovary under in vitro condition.
Methods: For this purpose, one-day-old mouse ovaries were initially cultured for 4 days with a base medium containing 5 IU hMG; thereafter, the culture medium was replaced with a fresh base medium containing 5 IU hMG and 0.1 mM testosterone and culture continued for variable days in various day groups. Ovarian samples were collected before medium replacement in day 4 group, and they were collected 1, 2, 3 and 4 days after medium replacement in on day 5, 6, 7 and 8 groups, respectively (n = 10 ovaries per each day group). Development of ovarian follicles were assessed using histological examination.
Results: The number of primordial follicles decreased between days 4 and 5, but it increased again between days 5 and 7 (P ≤ 0.05). The number of transitional follicles decrease between days 4 and 7 (P ≤ 0.05), but it had a non-significant increase between days 7 and 8 (P > 0.05). The number of primary and preantral follicles increased between day 4 and 5, and peaked on day 5; however, it decreased between days 5 and 8 (P ≤ 0.05).
Conclusion: In conclusion, there was a temporary activation of primordial follicles and development of activated follicles towards preantral stage after medium replacement, but these follicles degenerated shortly after development. After degeneration of this initial wave of follicles, evidence for formation of new primordial follicles was detected.
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