Related Experiment Video
Updated: Jun 19, 2026
Whole Ovary Immunofluorescence, Clearing, and Multiphoton Microscopy for Quantitative 3D Analysis of the Developing Ovarian Reserve in Mouse
Published on: September 3, 2021
Differences in oocyte development and estradiol sensitivity among mouse strains
Melissa E Pepling1, Emily A Sundman, Nicole L Patterson
1Department of Biology, Syracuse University, Syracuse, New York 13244, USA. mepeplin@syr.edu
Abstract:
Mouse oocytes develop in clusters of interconnected cells called germline cysts. Shortly after birth, the majority of cysts break apart and primordial follicles form, consisting of one oocyte surrounded by granulosa cells. Concurrently, oocyte number is reduced by two-thirds. Exposure of neonatal females to estrogenic compounds causes multiple oocyte follicles that are likely germline cysts that did not break down. Supporting this idea, estrogen disrupts cyst breakdown and may regulate normal oocyte development. Previously, the CD-1 strain was used to study cyst breakdown and oocyte survival, but it is unknown if there are differences in these processes in other mouse strains. It is also unknown if there are variations in estrogen sensitivity during oocyte development. Here, we examined neonatal oocyte development in FVB, C57BL/6, and F2 hybrid (Oct4-GFP) strains, and compared them with the CD-1 strain. We found variability in oocyte development among the four strains. We also investigated estrogen sensitivity differences, and found that C57BL/6 ovaries are more sensitive to estradiol than CD-1, FVB, or Oct4-GFP ovaries. Insight into differences in oocyte development will facilitate comparison of mice generated on different genetic backgrounds. Understanding variations in estrogen sensitivity will lead to better understanding of the risks of environmental estrogen exposure in humans.
Insights
Neonatal mouse oocyte development and estrogen sensitivity vary by strain. C57BL/6 ovaries showed higher estradiol sensitivity, impacting germline cyst breakdown and follicle formation.
Area of Science:
- Reproductive Biology
- Developmental Biology
- Endocrinology
Background:
- Mouse oocytes develop in germline cysts, which normally break down after birth to form primordial follicles.
- Oocyte numbers decrease significantly during this transition.
- Estrogenic compounds can disrupt cyst breakdown, leading to multiple oocyte follicles.
Purpose of the Study:
- To investigate strain-specific differences in neonatal mouse oocyte development and germline cyst breakdown.
- To compare estrogen sensitivity across different mouse strains.
- To understand the implications for comparing mouse models and human environmental estrogen exposure risks.
Main Methods:
- Examined neonatal oocyte development in FVB, C57BL/6, Oct4-GFP (F2 hybrid), and CD-1 mouse strains.
- Compared oocyte development and germline cyst breakdown processes among these strains.
- Assessed ovarian sensitivity to estradiol in different mouse strains.
Main Results:
- Significant variability in oocyte development was observed among the four mouse strains.
- C57BL/6 mouse ovaries exhibited greater sensitivity to estradiol compared to CD-1, FVB, and Oct4-GFP ovaries.
- Estrogen appears to disrupt normal germline cyst breakdown and oocyte development.
Conclusions:
- Mouse strain genetic background influences neonatal oocyte development and ovarian estrogen sensitivity.
- Understanding these variations is crucial for accurate interpretation of mouse model studies.
- Differences in estrogen sensitivity highlight potential risks of environmental estrogen exposure in humans.
