Assignment 9: The Reproductive System – Infertility Due: Friday, May 15, 2020 by 11:59PM | Google Classroom Grade: 50 Points Instructions: The aim of this case is to provide information pertaining to some of the most common causes of both male and female infertility. The focus on multiple causes of infertility is intended to help develop a better understanding the anatomy and physiology of each gender’s reproductive system. Becoming pregnant and producing offspring require the successful completion of the processes of ovulation, fertilization, and implantation. These complex processes are interdependent, and timing is of the utmost importance. Read the case presented below and answer all questions asked along the way. Include and cite outside sources to supplement answers. Infertility has been defined in many different ways. The World Health Organization (WHO) defines infertility as a disease of the reproductive system defined by failure to achieve a clinical pregnancy after 12 months or more of regular unprotected sexual intercourse. About one-third of infertility cases involve only the male partner, one-third involve only the female partner, and the remaining one-third of cases involve both partners and some other unidentifiable cause. Q: Any disruption in the process of meiosis could render either a male or female human incapable of successfully producing children. Which of the following statements regarding the stages of meiosis I is incorrectly associated with a major event that occurs during that specific stage? A. During anaphase I, one set of sister chromatids from each homologous pair separates from its partner as they are pulled to opposite poles of the cell by the spindle fibers. B. At the completion of telophase I, two genetically distinct diploid cells, each containing 23 individual homologous chromosomes, have formed. C. By the end of metaphase I, sister chromatids of homologous pairs line up on either side of the equator (or midline) of the cell, forming a double line of chromosomes. D. During prophase I, chromatin condenses concurrently with spindle fiber formation and the appearance of centrioles at the opposite poles of the cell. Q: Much of the physiology associated with the reproductive system involves events that occur at the chemical and cellular levels of structural organization. Understanding diseases and disorders requires a solid foundation and understanding of what “normal” human anatomy and physiology is. a) Discuss the difference between haploid and diploid cells. b) What would you expect to happen if you combined the chromosomes of two diploid cells? c) What would happen to the number of chromosomes in a gamete if meiosis I was eliminated by an environmental toxin? The causes of male infertility can be divided into three broad categories. Non-obstructive infertility, which accounts for approximately 60% of cases, includes those diseases, disorders, or abnormalities that lead to inadequate sperm production by the testes. Obstructive infertility, which accounts for approximately 38% of cases, includes those diseases, disorders and abnormalities that lead to a blockage that impedes the movement of otherwise normal sperm through the genital tract. Lastly, coital infertility, which accounts for the remaining 2% of cases, includes those diseases, disorders, or abnormalities that affect intromission (the action or process of inserting the penis into the vagina during sexual intercourse) or ejaculation (the process by which semen is expelled from the penis). Congenital bilateral absence of the ductus (vas) deferens (CBAVD) is an anatomical abnormality that leads to obstructive infertility in approximately 1% of infertile men. CBAVD is associated with two separate genetic defects, one of which is cystic fibrosis, a disorder involving both the respiratory and digestive systems. Nearly every man who has cystic fibrosis also has CBAVD. Despite the fact that the testes may produce normal sperm cells, there are no ducts through which sperm cells can leave the epididymis. Q: Most men that suffer from cystic fibrosis (CF) have an obstructive type of infertility that blocks the transportation of sperm through the ductus (vas) deferens. The production of sperm cells in the testes may be completely unaffected by CF. Which of the following statements regarding the different cells found in the testicular tissues is incorrectly associated with its location and/or function? A. Seminiferous tubules contain spermatogenic cells that secrete testosterone. B. Seminiferous tubules contain sustentacular cells that produce testicular fluid. C. Interstitial cells, found between the seminiferous tubules, secrete testosterone. D. Seminiferous tubules contain spermatogenic cells that produce sperm. Q: Varicocele, a condition in which the pampiniform venous plexus in the spermatic cord become enlarged, can cause non-obstructive infertility in males. This condition impairs the countercurrent heat exchange within the spermatic cord, which elevates the temperature in the scrotum. a) Explain the role of the pampiniform venous plexus in sperm production. b) Describe the effects that even a small increase in temperature has on sperm production. Chemicals called gonadotoxic agents can lead to non-obstructive infertility in males. Anabolic steroids, one type of gonadotoxic agent that is often used illegally as performance-enhancing drugs in male athletes, can cause a profound decrease in the production of testosterone, producing a condition called secondary hypogonadism. (By contrast, primary hypogonadism, which also leads to reduced testosterone production, is usually caused by a specific genetic defect.) Lowered testosterone levels resulting from anabolic steroid use interfere with both sperm production and the homeostatic mechanisms by which the endocrine system maintains the normal functions of the male reproductive system. Reduced testosterone production in secondary hypogonadism results from either a failure of the hypothalamus to produce gonadotropin-releasing hormone (GnRH) or a failure of the anterior pituitary gland to produce enough follicle-stimulating hormone (FSH) and luteinizing hormone (LH). In primary hypogonadism, the testes fail to respond to FSH and LH, which reduces the production of testosterone and impairs the negative feedback mechanisms among the testes, hypothalamus, and anterior pituitary gland. Q: A male professional athlete who has admitted to using anabolic steroids to help him recover from an injury more quickly is concerned that the use of this performance-enhancing drug could cause infertility. Note that the ingested drug and the testosterone the body normally makes are indistinguishable to the body. Which of the following statements describes how the hormonal regulation of testicular function and the hypothalamic-pituitary-gonadal axis (HPG axis) would be affected by the athlete’s use of anabolic steroids? A. Anabolic steroid use could decrease testosterone production by the interstitial cells by interfering with the release of luteinizing hormone from the anterior pituitary gland. B. Anabolic steroid use could increase testosterone production by the interstitial cells by interfering with the release of luteinizing hormone from the anterior hypothalamus. C. Anabolic steroid use could increase testosterone production by the interstitial cells by interfering with the release of gonadotropin-releasing hormone from the anterior pituitary gland. D. Anabolic steroid use could decrease testosterone production by the interstitial cells by increasing the release of gonadotropin-releasing hormone from the hypothalamus. Q: Anabolic steroids and other gonadotoxic agents can lead to non-obstructive infertility in men. Anabolic steroids can also mimic the effects of endogenous testosterone (testosterone made by the individual’s body) on other parts of the body. a) Describe the effects you would expect to see if an 8-year-old boy was given anabolic steroids, assuming that the boy has not yet reached puberty. b) Explain the difference between spermatogenesis and spermiogenesis. There is a long list of diseases, disorders, and anatomical abnormalities that can lead to infertility in women. One disorder, called endometriosis, occurs when cells from the lining of the uterus (specifically, the endometrium) grow in other areas of the body (such as the peritoneum); the result can be pain, irregular menstrual bleeding, and infertility. Although how endometriosis causes infertility is still unknown, it can lead to the development of adhesions, which are bands of scar tissue that form between two anatomical surfaces and stick them together. Such adhesions interfere with the ability of adjacent anatomical surfaces to move against one another, which can be painful and, in the case of endometriosis, disruptive to normal fertility. Endometriosis is also associated with the distortion of normal pelvic cavity anatomy to the extent that infertility can result. Adnexal masses—abnormal lumps of tissue that are usually located in an ovary or a uterine tube—are commonly associated with endometriosis. Adnexal masses include ovarian cysts, ectopic or tubal pregnancies, non-cancerous (benign) tumors, and cancerous (malignant) tumors. Adnexal masses can cause infertility by disrupting the functions of the surrounding anatomical structures in the pelvic cavity. Q: Endometriosis is the abnormal growth of endometrial tissue (one of the layers of the uterus) in sites outside the uterus. Which of the following statements incorrectly matches a layer of the uterus with its correct description? A. The perimetrium is the outermost layer of the uterine wall and is an extension of the parietal peritoneum. B. The myometrium, the thick middle layer of the uterine wall, is composed of smooth muscle that contracts rhythmically during orgasm, during childbirth, and during the menstrual cycle in some women. C. The endometrium, the outermost serous layer of the uterine wall, is an extension of the parietal peritoneum. D. The endometrium is the innermost layer of the uterine wall and is a mucous membrane composed of simple columnar epithelium on a layer of connective tissue called the lamina propria. Q: A female patient has an adnexal mass that has partially blocked both of her uterine tubes, preventing the passage of ovulated ova into the uterus. a) Discuss the anatomical and functional relationships between the ovaries and uterine tubes. b) What would you expect to happen if only cells no bigger than sperm cells could pass through these partially blocked uterine tubes? Polycystic ovarian syndrome (PCOS) is the most common cause of female infertility in the United States, affecting 5–10 percent of women. As the name implies, several cysts are commonly found within the ovaries, but the main cause of infertility is an associated hormonal imbalance that results in an excess of androgens (male sex hormones) that interferes with normal ovulation. In addition to infertility and ovarian cysts, typical signs of PCOS include mild obesity, slight hirsutism (abnormal hair growth in women that resembles normal hair growth in men), and irregular or absent menstrual periods. Although a definite cause of PCOS is not yet known, current medical thought targets the roles of hormonal imbalances and genetics. The risk of developing PCOS is higher in women whose mothers and/or sisters also developed the condition. Q: PCOS is thought to involve both genetics and an excess of the male sex hormones collectively known as androgens. Suppose that a genetic disorder impaired/prevented the production of the hormone human chorionic gonadotropin (hCG) by the developing embryo. Which of the following statements best describes what might happen to the uterus in the absence of hCG? A. The absence of hCG would cause the corpus luteum to degenerate, which would cause progesterone levels to drop. B. The estrogen level would drop, causing the corpus luteum to degenerate. C. The estrogen level would remain elevated, causing the corpus luteum to degenerate. D. The progesterone level would remain elevated, causing the corpus luteum to degenerate. Q: The androgen excess associated with PCOS can lead to characteristically male secondary sex characteristics in women who have the condition. Consider how other endocrine disorders that lead to hormone imbalances might affect female reproductive physiology. a) Describe the normal female secondary sex characteristics. b) Discuss the role of estrogen in a normal uterine cycle and describe how the cycle would be affected if estrogen was missing. Several common causes of both male and female infertility have been presented here, but no discussion of infertility would be complete without a discussion of the impact of sexually transmitted infections (STIs). STIs represents a situation, unlike the other conditions presented in this case, in which both partners are directly involved. STIs are transmitted from one sexual partner to the other and may go unnoticed until they become quite severe. One example of an STI in females is pelvic inflammatory disease (PID). PID is a medical term that describes a bacterial infection involving the pelvic organs in females, including the cervix, uterus, uterine tubes, and ovaries. Gonorrhea and chlamydia are sexually transmitted bacterial infections (STIs) commonly associated with PID, and in turn with infertility in women. These STIs are of particular concern because they may not cause any signs or symptoms until the infection has progressed to PID. Extreme pain and elevated temperature may appear quickly without warning, especially if gonorrhea is the infectious microorganism. Lower abdominal pain is the most common symptom associated with PID. Fever, malodorous vaginal discharge, painful urination, painful sexual intercourse, and irregular menstrual cycles are also commonly reported by women with gonorrhea or chlamydia. At greater risk for developing pelvic inflammatory disease are women who have previously had an STI, who are sexually active and under the age of 25, who have more than one sexual partner, who use intrauterine devices (IUDs), and who use douching products. Each risk factor increases the chance that once an STI is contracted it could lead to pelvic inflammatory disease and quite possibly to infertility. Q: What is a Sexually Transmitted Disease? What are the different types of STDs? What is the difference between an STD and an STI? Couples that are having problems becoming pregnant should seek the expertise of a healthcare provider that specializes in reproductive medicine. Several of the conditions presented in the preceding case can be treated medically or surgically. Fertility clinics can provide a broad range of options to couples that are struggling to become pregnant. Q: Describe the differences between intrauterine insemination (IUI) and in vitro fertilization (IVF).
