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Questions and Answers
What is the stage of development when the majority of germ cells have disappeared, and the surviving oocytes are individually encircled by pre-granulosa cells?
What is the process by which cohorts of follicles are activated from birth to menopause to undergo growth and development?
At what stage do oocytes start to synthesize the zona pellucida glycoproteins and become connected to surrounding granulosa cells?
When is the competence to resume meiosis achieved in oocytes?
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What is the diameter of fully grown oocytes in large antral follicles?
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How often does an adult female mouse produce fertilizable oocytes?
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What happens to the meiotic cell cycle in the oocytes inside the preovulatory antral follicles shortly before ovulation?
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What is the term for the block in the meiotic cell cycle that occurs shortly before ovulation?
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What is the duration of the Metestrus phase?
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What happens to the corpus luteum in the Diestrus phase?
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What is the primary cell type seen in the vaginal smear during the Metestrus phase?
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What is the main characteristic of the uterus during the Diestrus phase?
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When is copulation permitted in the estrous cycle?
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What happens to the corpus luteum in the Metestrus phase?
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What is the primary function of the corpus luteum in the Metestrus phase?
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What is the duration of the Diestrus phase?
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What is the primary characteristic of the proestrus phase in the rodent estrous cycle?
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What is the duration of the estrus phase in the rodent estrous cycle?
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What type of cells are predominantly seen in the vaginal smear during the proestrus phase?
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What is the primary event that occurs during the estrus phase?
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What is the primary function of the corpus luteum?
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What is the duration of the complete estrous cycle in rodents?
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What is the primary characteristic of the metestrus phase?
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What happens to the uterus during the estrus phase?
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Study Notes
Oogenesis
- At around 4 days post-partum, most germ cells disappear, and surviving oocytes are encircled by pre-granulosa cells, forming a primordial follicle (PF).
- The PF pool represents the ovarian reserve, from which cohorts of follicles are activated to undergo growth and development as primary and secondary follicles.
- Oocytes grow from 12-20 μm in diameter in primordial and primary follicles to 70 μm in medium-sized preantral follicles and eventually to a fully grown size of approximately 80 μm in large antral follicles.
- Growing oocytes synthesize zona pellucida glycoproteins and acquire competence to resume meiosis, undergo fertilization, and complete preimplantation development.
- Oocytes acquire competence to resume meiosis late in development, correlated with oocyte diameter (≥60 μm).
Folliculogenesis
- Folliculogenesis is the process by which cohorts of follicles are activated from the ovarian reserve to undergo extensive growth and development as primary and secondary follicles.
Oocyte Development
- Oocytes in preovulatory antral follicles reactivate meiosis, entering metaphase II arrest, which is dependent on fertilization for completion.
- An adult female mouse produces 4-12 fertilizable oocytes every 4-5 days for about 7-8 months.
Estrous Cycle Staging
- The estrous cycle consists of four stages: proestrus, estrus, metestrus, and diestrus.
- Each stage is characterized by specific vaginal smears, uterine changes, and duration.
Spermatogenesis
- Spermatogonial stem cell (SSC) activity resides in isolated (single) spermatogonia located on the basement membrane of the seminiferous tubules.
- Asingle spermatogonia (As) divide every three days and make up about 0.03% of total germ cells in the mouse testis.
- Mitotic division of As produces Apaired, which can either self-renew or differentiate into Aaligned spermatogonia (Aal4).
Rodent Estrous Cycle
- Rats and mice are spontaneous ovulators, with some evidence suggesting stimulation from male rodents can induce and/or hasten ovulation.
- The estrous cycle consists of four stages, with durations and characteristics specific to each stage.
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Description
This quiz covers the stages of the estrous cycle in rodents, including the role of ovulation and menstruation. Learn about the differences between the estrous and menstrual cycles and how they relate to sex urge and copulation.
