Question 1. What is the connective tissue capsule surrounding each testis called?
Question 2. What is a lobule of the testis?
Answer 2. Each testis is comprised of ~ 250 lobules separated by incomplete connective tissue septa. Each lobule contains 1-4 seminiferous tubules.
Question 3. What is the shape of seminiferous tubule?
Answer 3. These are convoluted loops, that connect at each end to tubules that convey sperm toward the epididymis (roughly �U� shaped).
Question 4. What are the primitive germ cells of the epithelium of the seminiferous tubule called, and where are they located?
Answer 4. They are called spermatogonia and they rest on the basal lamina.
Question 5. What are the products of mitotic division of the primitive germ cells in the seminiferous tubules?
Answer 5. At puberty the spermatogonia begin to divide. Their daughter cells will either remain as stem cell spermatogonia or become progenitor spermatogonia, which will continue to divide and then differentiate into primary spermatocytes.
Question 6. At what stage of spermatogenesis does meiosis I occur?
Answer 6. The primary spermatocytes proceed through meiosis I to become haploid secondary spermatocytes with two chromatids.
Question 7. What cells are the produced by meiosis II?
Answer 7. Secondary spermatocytes undergo meiosis II to create haploid spermatids.
Question 8. What happens in the process of spermiogenesis?
Answer 8. The spermatids will not divide further but will be transformed into mature spermatozoa by the process called spermiogenesis.
Question 9. What is unusual about the cytoplasm during cell divisions that result in spermatids?
Answer 9. In all the cellular divisions from a progenitor cell to the spermatids, the division of the cytoplasm is never complete. All daughter cells of one progenitor cell will remain connected by cytoplasmic bridges. The mature spermatozoa ultimately become individual cells by shedding their extra cytoplasm along with the bridges connecting them.
Question 10. Why is an undescended testis a problem?
Answer 10. Normal spermatogenesis requires a lower temperature than core body temperature (37¾C), and therefore an undescended (cryptorchid) testis will have impaired spermatogenic potential. Also, cryptorchid testes are much more likely to develop cancers.
Question 11. What cells are responsible for the blood-testis barrier and what are some unique features of these cells?
Answer 11. The Sertoli cells are epithelial cells that contact the basement membrane and that have tight junctions between cytoplasmic processes of adjacent cells. These junctional complexes create the blood-testis barrier. Larger molecules in the blood cannot cross this barrier, so the composition of the fluid in the seminiferous tubule varies from that in the blood. The exchange of nutrients to and metabolites from the developing spermatogenic cells is a function of Sertoli cells, which have no barrier between them and the capillaries deep to the basal lamina.
Question 12. Which cells that are involved in production of sperm are outside of the blood-testis barrier (i.e., are exposed to circulating macromolecules)?
Answer 12. The spermatogonia and early primary spermatocytes reside only in the basal compartment, i.e., in between the basal lamina and the junctional complexes of the Sertoli cells. Prior to the onset of meiosis I a primary spermatocyte must migrate to the luminal (other) side of the junctional complex where the remainder of spermatogenesis takes place.
Question 13. Why is the blood-testis barrier necessary?
Answer 13. The haploid spermatids are genetically different from the host and would be recognized as foreign. However, they are isolated from an immune response by the blood-testis barrier which prevents antigens from the germ cells reaching the systemic circulation and any resulting antibodies in the circulation from reaching the germ cells.
Question 14. What are the steps in spermiogenesis?
Answer 14. This process includes formation of the acrosome, nuclear condensation and elongation, development of the flagellum (a long cilium) and loss of cytoplasm. These flagella projecting into the lumen of the seminiferous tubule. Mitochondria spiral tightly around the proximal end of a flagellum providing an energy source. Before the spermatozoa are released into the lumen, excess cytoplasm is shed as residual bodies.
Question 15. What is the acrosome?
Answer 15. The acrosome is a structure that contains hydrolytic enzymes that permit the sperm to penetrate the corona radiata and zona pellucida of the ovum prior to fertilization.
Question 16. What happens to residual bodies?
Answer 16. Residual bodies and any spermatogenic cell that fails to differentiate completely are phagocytosed by the Sertoli cells.
Question 17. What are the cells that produce androgens, and where are they located?
Answer 17. Interstitial or Leydig cells are in the loose interstitial tissue between the seminiferous tubules. These cells synthesize testosterone.
Question 18. What are the factors that influence production of androgens in the testis?
Review Quizzes Examsreproductive System Answer
Answer 18. Testosterone is produced by the interstitial cells under the influence of luteinizing hormone (LH) from gonadotrophs in the adenohypophysis.
Question 19. What are the functions of testosterone?
Answer 19. Testosterone is needed for the development and maintenance of spermatogenesis, secondary male sexual characteristics, accessory sex gland secretion and genital ducts.
Question 20. What is the hormonal control of Sertoli cells?
Answer 20. Follicle stimulating hormone (FSH), also from the same pituitary gonadotrophs, stimulates Sertoli cells to synthesize and secrete androgen-binding protein (ABP). This helps to concentrate testosterone in the luminal compartment of the seminiferous tubule where it is essential for normal spermatogenesis.
Question 21. What are the ducts that convey sperm from the seminiferous tubules to the epididymis and what is their lining?
Answer 21. Leaving the seminiferous tubules, spermatozoa will pass through the tubuli recti (lined with simple cuboidal epithelium) and then through the rete testis (also simple cuboidal). They then pass through the efferent ductules (partially lined ciliated epithelium to help propel the still immotile sperm) and into the epididymis.
Question 22. What is the structure of the epithelium of the epididymis?
Answer 22. The epididymis is lined by a pseudostratified columnar epithelium with long stereocilia.
Question 23. What essential role is played by the epididymis?
Answer 23. The epididymis resorbs a large amount of fluid and stores the sperm until they are released. However, their most important function is that spermatozoa develop their motility during their progression through the epididymis. Without a sufficient amount of time in the epididymis, sperm would not be capable of fertilization. The precise mechanisms for this are not known.
Question 24. What is the structure of the vas (ductus) deferens?
Answer 24. The vas deferens has the same epithelium as the epididymis but has a much thicker muscular wall. Its dilated distal end, located on the posterior surface of the urinary bladder, is called the ampulla and joins with the exit of the seminal vesicle to form the ejaculatory duct, which travels through the prostate gland to empty into the prostatic urethra.
Question 25. How does emission take place?
Answer 25. Emission results from activation of the sympathetic nervous system, which causes peristaltic contraction of the smooth muscle in the wall of the epididymis and vas deferens.
Question 26. What is the structure of the lining of the urethra?
Answer 26. The urethra has prostatic, membranous and penile portions. The epithelium in the penile portion is predominately stratified columnar transitioning to stratified squamous in its distal portion. Mucus secreting urethral glands (of Littré) are present throughout the penile urethra.
Question 27. What is the structure of the seminal vesicles?
Answer 27. The seminal vesicles have a convoluted glandular mucosa covered by a pseudostratified, non-ciliated epithelium that is secretory. The stroma of the seminal vesicles contains an abundance of smooth muscle whose contraction impels the seminal fluid into the ejaculatory duct during emission.
Question 28. What do the seminal vesicles do?
Answer 28. The epithelium secretes a fructose-rich secretion, which is a source of energy for spermatozoa. It does NOT store spermatozoa despite the implications of its name.
Question 29. What is the structure of the prostate gland?
Answer 29. The prostate consists of glandular tissue surrounded by a fibromuscular stroma. The glands are lined by tall columnar or pseudostratfied epithelium. These glands add secretions to the semen. In older men the glands often contain prostatic concretions (corpora amylacea) within the glandular lumens.
Question 30. What is the significance of different zones of the prostate?
Answer 30. There are 3 concentric zones of the prostate. Zone 1 is a central zone surrounding the prostatic urethra. This is the major site of benign prostatic hyperplasia, which often results in constriction of the urethra early in its course. Zone 2 is a transition zone that surrounds the central zone and the ejaculatory ducts. Zone 3 is a peripheral zone, which comprises the majority of the prostate. This is the area where most prostate cancers occur. Therefore, urinary obstruction is usually a late sign of prostate cancer (if it happens at all). On the other hand, this makes prostate cancer more detectable by rectal examination.
Question 31. What are the bulbourethral glands and where are they located?
Answer 31. The bulbourethral (Cowper's) glands lie superior (deep) to the perineal membrane. Their cuboidal epithelium secretes a clear mucus through ducts into the proximal penile urethra inferior to the perineal membrane.
Question 32. What is the structure of the erectile tissues of the penis?
Answer 32. The erectile tissue is made up of a network of endothelial-lined vascular sinuses supported by a network of fibromuscular trabeculae. The engorgement of these sinuses by arterial blood results in erection. The three cylinders of erectile tissue are surrounded by a tunica albuginea. This fibrous sheath is much thicker and more rigid over the corpora cavernosa than over the corpus spongiosum. The glans penis is the distal portion of the corpus spongiosum and has a similarly thin connective tissue capsule.
Question 33. What is the significance of the different connective tissue capsule around the corpus spongiosum and corpora cavernosa?
Answer 33. The thick tunica albuginia around the corpora cavernosa compress venous return and result in a much more rigid structure. The corpus spongiosum, containing the penile (spongy) urethra, does not become as rigid, permitting ejaculation.
Define the following terms:
Endometrium,myometrium,stratum functionalis,stratum basale,endocervix, ectocervix.
The fibromuscular layer of the uterus, dominated by smooth muscle fibers.
This is the portion of the uterine lining that undergoes changes (including loss) as part of the menstrual cycle.
This is the stable part of the uterine lining that remains after menstruation. This is the part from which the functionalis is reconstituted.
This is the part of the cervix connecting the uterine cavity with the opening into the vagina (the external os).
This is the part of the cervix that is exposed to the vagina.
Answer the following questions:
Review Quizzes Examsreproductive System Mechanic
Question 1. What is the outermost layer of the ovary?
Answer 1. The surface of the ovary is covered by the germinal epithelium (modified peritoneal layer) that is mostly cuboidal epithelium.
Question 2. What is the thick connective tissue layer that surrounds the parenchyma of the ovary called?
Answer 2. The entire ovary is encased within a connective tissue capsule called the tunica albuginea.
Question 3. Where in the ovary would you find the various stages of the female gamete?
Answer 3. The cortex of the ovary is the site of generation of the female gamete or ovum (including developing follicles [oocyte + supportive cells] and surrounding stromal cells.
Question 4. In what phase of replication are primary oocytes arrested?
Answer 4. Primary oocytes are arrested in prophase of meiosis I until puberty or beyond.
Question 5. What surrounds the oocyte when it is in a primary follicle?
Review Quizzes Examsreproductive Systems
Answer 5. The oocyte secretes the constituents of the zona pellucida which surrounds it until well after fertilization.
Question 6. What is the difference in appearance between a primordial and a primary follicle?
Answer 6. The primordial follicle is surrounded by flattened, squamous-appearing epithelial cells and no evident zona pellucidum. In the primary follicle, there is a prominent zona pellucidum and a single layer of cuboidal granulosa cells. .
Question 7. What hormone stimulates a cohort of primary follicles to mature?
Answer 7. The further development of a cohort of preantral follicles will be stimulated each month by follicle stimulating hormone (FSH) and secondary (antral) follicles will be formed.
Question 8. What is the main product of the granulosa cells of the antral follicle and what causes them to produce this?
Answer 8. With stimulation by both FSH and luteinizing hormone (LH), the granulosa cells, working together with a population of modified stromal cells, the theca interna, will begin producing estrogens.
Question 9. What is the appearance of the Graafian follicle?
Answer 9. The fully mature, Graafian follicle is characterized by a large antrum filled with the liquor folliculi, and containing an oocyte within a collection of granulosa cells, the cumulus oophorus. The granulosa cells surrounding the oocyte are the corona radiata.
Question 10. What is the main trigger for the �LH surge�?
Answer 10. Increasing levels of estrogen result in an LH surge which then triggers the completion of meiosis I and the process of ovulation. Typically only one of the cohort of antral follicles will be ovulated,
Question 11. What happens to the other Graafian follicles that have matured but not ovulated during the cycle?
Answer 11. The remainder of the follicles will undergo degeneration into atretic follicles (corpora fibrosa).
Question 12. What happens to the follicle immediately after ovulation?
Answer 12. Following ovulation, the remnant of the follicle will be converted into a corpus luteum (CL). This has two components, a granulosa lutein and a theca lutein. Residual LH will stimulate these cells to produce progesterone (and some estrogen).
Question 13. What happens to the corpus luteum if fertilization does not take place?
Answer 13. In the absence of pregnancy, the corpus luteum will degenerate into a corpus albicans and the ovarian cycle will begin again.
Question 14. What is the main stimulus for the proliferative phase of the endometrium?
Answer 14. Estrogen from the maturing follicles stimulates the proliferative phase of the endometrial cycle.
Question 15. What happens to the endometrium during the proliferative phase of the menstrual cycle?
Answer 15. During the proliferative phase of the endometrium, endometrial tissues, both epithelial tissues and stromal cells, are mitotically active. This results in the development of a thick stratum functionalis layer from the underlying stratum basalis.
Question 16. What is the main stimulus for the secretory phase of the endometrium?
Answer 16. Progesterone from the corpus luteum leads to the secretory phase.
Question 17. What happens during the secretory phase of the endometrium?
Answer 17. The endometrial glands begin production of glycogen-rich secretions in anticipation of nourishing an implanted embryo.
Question 18. What triggers menstruation?
Answer 18. In the absence of pregnancy, estrogen and progesterone levels drop. This results in contraction of the spiral arteries supplying the endometrium, leading to the necrosis of the stratum functionalis and its sloughing during the menstrual phase.
Question 19. At what stage is the oocyte at the time of ovulation?
Answer 19. Ovulation marks the completion of meiosis I and the formation of a secondary oocyte (i.e., becomes haploid).
Question 20. What happens to the cell cycle of the secondary oocyte?
Answer 20. It arrests in the metaphase of Meiosis II and will only finish this if it is fertilized.
Question 21. How is the oocyte moved through the uterine tube?
Answer 21. Both ciliary action and peristaltic waves generated by the smooth muscle layers of the oviduct help propel the egg through the isthmus, into the intramural portion of the oviduct and finally into the uterine cavity. The mucosa of the oviduct, especially the distal end, is thrown into numerous folds, and is covered by a ciliated, simple columnar epithelium that sweep toward the uterine cavity. At the time of ovulation, the secondary oocyte is usually swept into the fimbriated end or infundibulum of the oviduct and then into its ampulla.
Question 22. What is the function of �peg� cells?
Answer 22. A population of secretory peg cells provided some nutritive secretions.
Question 23. Where does fertilization usually take place?
Answer 23. Fertilization usually occurs in the distal segment of the oviduct when a spermatozoon penetrates the protective layer of granulosa cells and then enzymatically digests its way through the zona pellucida (the function of acrosomal enzymes). This allows for the fusion of the egg and sperm membranes.
Question 24. What prevents polyspermia?
Answer 24. Penetration of the oocyte by the sperm triggers a calcium flux in the oocyte resulting in discharge of cortical granules, producing a block to polyspermy.
Question 25. When does implantation of the blastocyst usually take place?
Answer 25. Implantation of the blastocyst into the endometrium usually occurs by day 7 (post-fertilization).
Question 26. Where is the most common location of ectopic implantation?
Answer 26. Ectopic implantation most commonly occurs in the oviduct (tubal pregnancy).
Question 27. What cells of the blastocyst invade the endometrium?
Answer 27. The syncytiotrophoblast layer leads invasion of the endometrium by the blastocyst.
Question 28. What cells produce hCG and why is it important?
Answer 28. The production of human chorionic gonadotropin (hCG) by the syncytiotrophoblast is essential to the survival of the implanted embryo. This hormone provides continued stimulation of the corpus luteum (now a CL of pregnancy), and thus continued maintenance of the endometrium (now called the decidua). In subsequent weeks, the placenta will also become an important source of other hormones (e.g. estrogen, progesterone) necessary for normal gestation.
Question 29. What is the histologic structure of the cervix?
Answer 29. The uterine cervix is characterized by a dense fibromuscular stroma that maintains the narrow opening of the cervix and prevents fetal loss until it is softened late in pregnancy by the action of hormones. There is also a secretory mucosal layer responsible for the production of cervical mucus, the consistency of which changes during the menstrual cycle. The simple columnar epithelium of the endocervix gives way to a stratified squamous epithelium where the ectocervix is exposed to the vaginal environment.
Question 30. What is important about the site of transition from simple columnar to stratified squamous epithelium in the cervix?
Answer 30. The transformation zone where metaplasia occurs is the common site of development of cervical cancer, but dysplastic or neoplastic cell growth at this site can be readily monitored by means of Pap smears.
Question 31. What kind of epithelium lines the vagina?
Answer 31. The vagina is lined by a stratified squamous non-keratinized epithelium. The cells of the lining show changes during the monthly cycle, most notably in the quantity of glycogen produced by the cells.
Question 32. Are there any glands in the vagina?
Answer 32. Glands are lacking in the vaginal mucosa.
Question 33. What comprises the remainder of the walls of the vagina?
Answer 33. The walls of the vagina are supported by a well-vascularized fibroelastic connective tissue, smooth muscle, and, at some levels, skeletal muscle from the urogenital diaphragm.
Question 34. What comprises the histologic structure of the labia majora and minora?
Answer 34. The vulva includes the labia majora and labia minora, both folds of skin containing sebaceous and sweat glands. The hair follicles and adipose tissue of the labia majora are not found in the labia minora.
Question 35. What is the histologic structure of the clitoris?
Answer 35. The clitoris represents a body of erectile tissue, comprised of a network of large, endothelial-lined sinuses supported by a network of fibromuscular trabeculae and surrounded by a thick connective tissue capsule (the tunica albuginia).
