IntroductionThe reproductive system in females is responsible for producing gametes (called eggs or ova), certain sex hormones, and maintaining fertilized eggs as they develop into mature fetuses and become ready for delivery. A female’s reproductive years are between menarche (the first menstrual cycle) and menopause (cessation of menses for 12 consecutive months). During this period, cyclical expulsion of ova from the ovary occurs, with the potential to become fertilized by male gametes (sperm). This cyclic expulsion of eggs is a normal part of the menstrual cycle. Show DevelopmentFemale gametes derive from germ cells. In utero, oogonia rapidly divide until approximately 7 million germ cells form by the 7th month of gestation. The number of germ cells then rapidly declines; most oogonia perish while the remaining cells, primary oocytes, begin the first meiotic division. These cells arrest in prophase I and remain dormant as such until menarche.[1][2][3][4] A primordial follicle made up of granulosa and theca cells surrounds each oocyte. When primordial follicles mature, the granulosa cells proliferate to form concentric layers around the oocyte. The oocyte itself undergoes a drastic volume increase. With the onset of menarche, finite groups of oocytes periodically resume meiosis and continue to develop. At the time of fertilization, oocytes are arrested in metaphase II. The oocyte becomes an ovum as it expels its second polar body, and meiosis resumes when the egg undergoes activation by a sperm cell (a male gamete).[1][2][3][4] Organ Systems InvolvedFemale Reproductive Organs Ovaries
Fallopian Tubes
Uterus
Vagina
Vulva
FunctionMenarche is a female’s first menstrual cycle, marked by her first episode of menstrual bleeding. Menarche occurs during puberty, preceded by breast growth, axillary and pubic hair growth, and a growth spurt. At the initiation of each menstrual cycle, a number of primordial follicles in the female’s ovaries continue development. One becomes the dominant follicle and continues to grow while the other follicles become atretic and cease to develop. The dominant follicle develops into a Graafian follicle, at which point meiosis I has completed, and the ovum is no longer in prophase I arrest.[1][2][3][4] At ovulation, the Graafian follicle expels the ovum from its surrounding tissue, henceforth called the corpus luteum. If no fertilization takes place, the expulsion of the egg occurs from the uterus along with the secretory endometrial lining under the influence of declining levels of progesterone; this presents as menstrual bleeding. If fertilization does occur, the fertilized egg implants in the endometrial wall and the endometrial lining is maintained by progesterone secreted (initially) by the corpus luteum until the placenta takes over.[1][2]][4] MechanismThe normal menstrual cycle divides into the follicular and luteal phases, with ovulation occurring between phases. The follicular phase begins with menstrual bleeding and ends right before the LH (luteinizing hormone) surge. The luteal phase begins with the LH surge and ends with the onset of menses. A typical cycle lasts approximately 28 days; the luteal phase lasts 14 days, while the follicular phase is more variable in its time course. Low serum levels of estradiol and progesterone mark the beginning of the follicular phase. The lack of inhibitory feedback allows for an increase in pulsatile GnRH (gonadotropin-releasing hormone) levels, leading to elevations in FSH (follicular stimulating hormone) and LH.[13][14][15] This rise in FSH levels stimulates follicular maturation, resulting in a select number of follicles' continued growth. The growth of these follicles results in increasing FSH and estradiol levels. By the end of the follicular phase, the dominant follicle has emerged and increased to a size of approximately 20-25mm. The increase in estradiol induces thickening of the endometrium to accommodate the potential implantation of a fertilized egg. When estradiol levels reach a critical level, the negative feedback effect of estradiol on LH becomes a positive feedback effect, resulting in a massive surge in LH concentration (and a smaller surge in FSH levels.)[13][15][16] Approximately 36 hours following the LH surge, the oocyte is released from the dominant follicle and travels into the uterus via the fallopian tube.[14] The corpus luteum (the remaining follicular tissue following oocyte expulsion) releases progesterone, inhibiting the release of LH and FSH and stimulating the formation of the secretory endometrium.[14][17] In the absence of fertilization, declining LH levels contribute to a decline in progesterone and estradiol levels.[15][16] In the presence of fertilization, the oocyte implants into the endometrium and releases chorionic gonadotropin, which maintains the corpus luteum and, thus, progesterone production.[13][15] Clinical SignificanceThe clinical relevance of female reproductive physiology comes to bear for clinical issues ranging from adolescent entry into child-bearing years, pregnancy, infertility issues, and menopause. Review QuestionsReferences1.Rimon-Dahari N, Yerushalmi-Heinemann L, Alyagor L, Dekel N. Ovarian Folliculogenesis. Results Probl Cell Differ. 2016;58:167-90. [PubMed: 27300179] 2.Channing CP, Schaerf FW, Anderson LD, Tsafriri A. Ovarian follicular and luteal physiology. Int Rev Physiol. 1980;22:117-201. [PubMed: 6248477] 3.Channing CP, Hillensjo T, Schaerf FW. Hormonal control of oocyte meiosis, ovulation and luteinization in mammals. Clin Endocrinol Metab. 1978 Nov;7(3):601-24. [PubMed: 215357] 4.Machaty Z, Miller AR, Zhang L. Egg Activation at Fertilization. Adv Exp Med Biol. 2017;953:1-47. [PubMed: 27975269] 5.Richardson GS. Ovarian physiology. N Engl J Med. 1966 May 12;274(19):1064-75 contd. [PubMed: 5326705] 6.Puppo V. Embryology and anatomy of the vulva: the female orgasm and women's sexual health. Eur J Obstet Gynecol Reprod Biol. 2011 Jan;154(1):3-8. [PubMed: 20832160] 7.Hofmeister FJ. Pelvic anatomy of the ureter in relation to surgery performed through the vagina. Clin Obstet Gynecol. 1982 Dec;25(4):821-30. [PubMed: 7160117] 8.DeLancey JO. Anatomic aspects of vaginal eversion after hysterectomy. Am J Obstet Gynecol. 1992 Jun;166(6 Pt 1):1717-24; discussion 1724-8. [PubMed: 1615980] 9.Richardson AC. The rectovaginal septum revisited: its relationship to rectocele and its importance in rectocele repair. Clin Obstet Gynecol. 1993 Dec;36(4):976-83. [PubMed: 8293598] 10.DeLancey JO. Structural anatomy of the posterior pelvic compartment as it relates to rectocele. Am J Obstet Gynecol. 1999 Apr;180(4):815-23. [PubMed: 10203649] 11.de Ziegler D, Pirtea P, Galliano D, Cicinelli E, Meldrum D. Optimal uterine anatomy and physiology necessary for normal implantation and placentation. Fertil Steril. 2016 Apr;105(4):844-54. [PubMed: 26926252] 12.Foti PV, Ognibene N, Spadola S, Caltabiano R, Farina R, Palmucci S, Milone P, Ettorre GC. Non-neoplastic diseases of the fallopian tube: MR imaging with emphasis on diffusion-weighted imaging. Insights Imaging. 2016 Jun;7(3):311-27. [PMC free article: PMC4877350] [PubMed: 26992404] 13.Filicori M, Santoro N, Merriam GR, Crowley WF. Characterization of the physiological pattern of episodic gonadotropin secretion throughout the human menstrual cycle. J Clin Endocrinol Metab. 1986 Jun;62(6):1136-44. [PubMed: 3084534] 14.Adams JM, Taylor AE, Schoenfeld DA, Crowley WF, Hall JE. The midcycle gonadotropin surge in normal women occurs in the face of an unchanging gonadotropin-releasing hormone pulse frequency. J Clin Endocrinol Metab. 1994 Sep;79(3):858-64. [PubMed: 7521353] 15.Taylor AE, Whitney H, Hall JE, Martin K, Crowley WF. Midcycle levels of sex steroids are sufficient to recreate the follicle-stimulating hormone but not the luteinizing hormone midcycle surge: evidence for the contribution of other ovarian factors to the surge in normal women. J Clin Endocrinol Metab. 1995 May;80(5):1541-7. [PubMed: 7744998] 16.Filicori M, Butler JP, Crowley WF. Neuroendocrine regulation of the corpus luteum in the human. Evidence for pulsatile progesterone secretion. J Clin Invest. 1984 Jun;73(6):1638-47. [PMC free article: PMC437074] [PubMed: 6427277] 17.Stocco C, Telleria C, Gibori G. The molecular control of corpus luteum formation, function, and regression. Endocr Rev. 2007 Feb;28(1):117-49. [PubMed: 17077191] What is the term for a female reproductive cell?In the human reproductive process, two kinds of sex cells, or gametes (GAH-meetz), are involved. The male gamete, or sperm, and the female gamete, the egg or ovum, meet in the female's reproductive system.
Which of the following terms is used to describe the female reproductive cells quizlet?The ovaries produce the female sex cells, called eggs or ova, and sex hormones. The ova are released from follicles on the ovary.
Which of the following terms is used to describe the production of female gametes?Female Gamete Oogenesis Process
The process of the production of female gametes is referred to as oogenesis. Oogenesis occurs during embryo development, where cells referred to as primary oocytes multiply and remain dormant until puberty. The human female is born with around 400,00 primary oocytes.
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