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Questions and Answers
What is the primary function of the zona protein ZP3 during fertilization?
What is the primary function of the zona protein ZP3 during fertilization?
What occurs immediately after the fusion of the sperm and egg membranes?
What occurs immediately after the fusion of the sperm and egg membranes?
Which step is crucial in preventing polyspermy during fertilization?
Which step is crucial in preventing polyspermy during fertilization?
After a sperm enters the secondary oocyte, what is the outcome of the oocyte's division?
After a sperm enters the secondary oocyte, what is the outcome of the oocyte's division?
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What prevents the binding of additional sperm to the egg during fertilization?
What prevents the binding of additional sperm to the egg during fertilization?
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What primarily occurs to the majority of follicles during the menstrual cycle?
What primarily occurs to the majority of follicles during the menstrual cycle?
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Which hormone is primarily associated with the support of the dominant follicle?
Which hormone is primarily associated with the support of the dominant follicle?
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Which event marks the transition of the primary oocyte to a secondary oocyte?
Which event marks the transition of the primary oocyte to a secondary oocyte?
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By what age are only approximately 26,000 oocytes estimated to remain in the ovaries?
By what age are only approximately 26,000 oocytes estimated to remain in the ovaries?
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What is the primary cause of follicular atresia in non-dominant follicles?
What is the primary cause of follicular atresia in non-dominant follicles?
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What happens to the polar bodies produced during oocyte division?
What happens to the polar bodies produced during oocyte division?
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Which cell type is the primary source of cholesterol for ovarian steroidogenesis?
Which cell type is the primary source of cholesterol for ovarian steroidogenesis?
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What prevents the dominant follicle from experiencing a drop in FSH levels?
What prevents the dominant follicle from experiencing a drop in FSH levels?
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What significant role does the corpus luteum play during the luteal phase?
What significant role does the corpus luteum play during the luteal phase?
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What happens to the corpus luteum if pregnancy does not occur?
What happens to the corpus luteum if pregnancy does not occur?
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What triggers the luteinization process in granulosa and theca interna cells?
What triggers the luteinization process in granulosa and theca interna cells?
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During the proliferative phase of the uterine cycle, what primarily contributes to the re-establishment of the endometrial surface?
During the proliferative phase of the uterine cycle, what primarily contributes to the re-establishment of the endometrial surface?
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What hormone is secreted by the placenta that can prolong the life of the corpus luteum during pregnancy?
What hormone is secreted by the placenta that can prolong the life of the corpus luteum during pregnancy?
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What results from the decrease in progesterone and estrogen concentrations following the degeneration of the corpus luteum?
What results from the decrease in progesterone and estrogen concentrations following the degeneration of the corpus luteum?
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What characterizes the luteal phase of the menstrual cycle?
What characterizes the luteal phase of the menstrual cycle?
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Which of the following correctly describes the process of luteinization?
Which of the following correctly describes the process of luteinization?
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Study Notes
The Female Reproductive System
- The female reproductive system has three significant functions: gametogenic, endocrinologic, and nurture and protection of the fertilized ovum until it can exist independently.
- Gametogenic function is the creation of ova, leading to the continuation of a species.
- Endocrinologic function relates to the production of female hormones like estrogens and progestins.
- Nurturing and protecting the fertilized ovum involved in caring for the fetus until it can survive on its own.
Structure of the Female Reproductive System
- The female reproductive system incorporates various organs including the uterine tubes, ovaries, uterus, urinary bladder, symphysis pubis, urethra, clitoris, labia minor, labia major, and vaginal orifice.
- The diagram illustrates the position and organization of these components in the female anatomy.
Ovary Histology
- The ovary has two main functional regions: cortex and medulla.
- The cortex contains follicles and stroma. Follicles consist of an oocyte, granulosa cells, and theca cells.
- The medulla contains steroid-producing cells.
Oogenesis
- Oogenesis is the development of female gametes or ova.
- The process begins with oogonia in the embryonic period, which undergo mitotic divisions. They become primary oocytes, pausing in meiosis I prophase. They remain dormant until puberty.
- The monthly cycle involves the maturation of 20 primordial follicles into primary follicles, with some becoming secondary follicles. Each monthly cycle, various numbers of these follicles begin to develop to become larger antral follicles. Only one, known as the dominant follicle, continues its development.
- During an average woman's life, around 400 to 500 follicles will ovulate.
- A primary follicle contains an immature oocyte surrounded by a single layer of granulosa cells. During follicular development, the oocyte grows in size and the granulosa cells multiply and form multiple layers, and eventually develop an antrum.
- Folliculogenesis describes follicle development. Follicles progress to several stages ranging from primordial, primary, secondary to a vesicular/antral follicle.
- When a follicle matures, ovulation occurs and an ovum (secondary oocyte) is released.
- One or two secondary follicles might mature to form a vesicular follicle, and release a secondary oocyte into the oviduct.
- The secondary oocyte is in prophase of the second meiotic division. If fertilization occurs, it completes the second meiotic division to become a mature ovum. If fertilization does not occur, the secondary oocyte degrades.
- Ovulation occurs when the follicle ruptures and releases the ovum (secondary oocyte). This usually occurs approximately 14 days after the start of menstruation. The secondary oocyte will then travel to one of the uterine tubes (oviduct).
Different Stages in the Development of an Ovum and Follicle
- The table summarizes the process of ovum and follicle development across various stages in a woman's life, from fetal life to parturition.
Ovarian Cycle and Menstrual Cycle
- The ovarian cycle and the uterine cycle are interconnected.
- The ovarian cycle comprises three phases: follicular, ovulatory, and luteal phases.
- The uterine cycle includes three phases: menstrual, proliferative, and secretory phases.
- Each phase is characterized by specific hormonal fluctuations (estrogen and progesterone).
- The follicular phase begins around the 1st day of menstruation, stimulating follicle growth in the ovaries, and increasing estrogen levels. In the proliferative phase, the uterine lining is repaired. This is controlled by increasing estrogen levels. The ovulatory phase peaks at approximately day 14 with ovulation. The luteal phase begins after ovulation and ends with menstruation. The uterine lining thickens further, under the influence of increasing progesterone, preparing the uterus for potential implantation of a fertilized ovum, while decreasing estrogen levels.
Follicular Atresia
- Follicular atresia is the process of degeneration of follicles.
- Factors such as lack of gonadotropin support, inadequate FSH and LH receptors, and dysfunction in granulosa cells can contribute to this process.
Corpus Luteum Formation
- After ovulation, the follicle transforms into the corpus luteum.
- Lutein cells develop from the ruptured follicle cells.
- The corpus luteum produces progesterone and estrogen.
- The function of the corpus luteum is to prepare the uterus for pregnancy. If pregnancy does not happen, the corpus luteum degenerates.
Human Chorionic Gonadotropin (hCG)
- hCG is a hormone produced by the placenta.
- hCG helps maintain the corpus luteum and keeps estrogen and progesterone levels high until the placenta is capable of producing enough estrogen and progesterone for sustaining the ongoing pregnancy.
Human Placental Lactogen (hPL)
- hPL is a hormone produced by the placenta.
- hPL involves stimulating lipolysis, inhibiting glucose uptake by the mother, promoting transportation of glucose and protein to the fetus, maintaining an adequately high blood glucose levels for the developing fetus, and developing maternal insulin resistance.
Functions of the Placenta
- The placenta's functions include respiration, nutrition, secretion (removal of waste products), and storage of some hormones. Various hormones are exchanged between the mother and the fetus.
Implantation of the Blastocyst
- After fertilization and several days of division, the implanted blastocyst attaches to and begins to embed in the uterine wall.
- Trophoblast cells release enzymes to create space to implant the blastocyst, a process that involves significant cellular and molecular processes.
- Trophoblast cells form the placenta, and the inner cell mass becomes the embryo or fetus.
Ovum and Sperm Transport, Fertilization, and Implantation
- Sperm and ovum have to meet for fertilization to occur.
- Sperm travels from the vaginal canal to the uterine tube.
- Ovum moves from the ovulation site to one of the uterine tubes (oviduct).
- Once they fuse, the developing ovum migrates to the uterus, where it implants.
Puberty and Menarche
- Puberty is the period when the female body becomes capable of producing an ovum.
- The hypothalamus releases GnRH, which stimulates the pituitary gland to secrete FSH and LH. FSH and LH ultimately stimulate estrogen production.
- Menarche is the first occurrence of menstruation.
- Menarche, also sometimes called puberty, begins between ages 11 and 16—average of 13 years.
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Description
Test your knowledge of the female reproductive system, including its functions such as gametogenic, endocrinologic, and the nurturing of the fertilized ovum. Explore the anatomy and histology of the ovaries and related structures. This quiz is perfect for biology students looking to deepen their understanding of female reproductive anatomy.
