this lecture covered the anatomy and embryology of the male and female reproductive systems, first introduced in histology last semester. first it went through basic anatomical features of the female reproductive system. at the end of the vagina is the cervix, which is the opening to the uterus (the areas beside the cervix are called "fornices"). the uterus has four sections, the cervix, isthmus, body, and fundus. the uterine tubes branch off of the uterus and are divided into section as well: isthmus, ampula (where fertilization takes place), infundibulum, ending in the fimbria which open up into the peritoneal cavity. the uterus itself can be tilted forward, called anteversion, and additionally bent forward, called anteflexion. it is held in place by the round ligament, the uterosacral ligament, and the transverse sacral ligament. the ovaries are held in place by suspensory and ovarian ligaments.
the male reproductive anatomy basically follows spermatogenesis as it begins in the testes and ends at the penis. spermatogenesis occurs in the seminiferous tubules of the testis, aided by sertoli cells and leydig cells (which secrete testosterone). the spermatogonia in the walls of the tubules develop into spermatocytes, into spermatids, into spermatozoans, which are then released from the tubules. they travel into the rete testis, and into the ductus epididymus, which is a 4-5m long highly coiled tube where spermatozoans mature. from there they travel up the ductus deferens, which goes through the inguinal canal and behind the bladder, encountering the first of the ducts which combine with sperm to create seminal fluid.
the first of these is the seminal vesicles, which secrete a whitish viscous fluid containing fructose (recall the polyol pathway from biochemistry, and how sperm cells use fructose instead of glucose for metabolism). next is the ejaculatory ducts, which meet the urethra at the urethric crest of the prostate. next is the prostatic ducts in the prostate. finally, the bulbourethral gland is embedded in the external urethral sphincter and lubricates the penile urethra as well as neutralizing acidity from the urine.
some homologies of external genitalia between males and females are discussed: the penis and clitoris are both formed from the "genital tubercle". the "labiascrotal swelling" forms the scrotum in males and the labia majora in females. the urethral folds forms the urethra in males and the labia minora in females.
next we discuss the embryology of the reproductive systems. male/female differentiation begins around 4 weeks during development. before this point, germ cells in both sexes migrate from the yolk sac to the sex cords, forming the precursor to the gonads. in males, the mesonephric ducts (wolffian) develop while the paramesonephric (mullerian) ultimately degrade. the mesonephric ducts form the efferent ductules, ductus deferens, seminiferous tubules, and ejaculatory ducts.
in females, the follicles (recall the anatomy from the histology lecture) are formed by sex cords which form cortical cords, which form follicles. inside the follicles are oogonia, which began forming and dividing from the germ cells that migrated from the yolk sac. as mentioned above, the mesonephric duct eventually disappears and the paramesonephric duct develops into the female reproductive anatomy: the top of the ducts form the uterine tubes, ending in the infundibulum, and the bottom of the ducts form the uterus and vagina. the sinovaginal bulb is formed by the fusion of the urogenital sinus and the paramesonephric ducts, and the opening to the vagina forms by the hollowing out of the sinovaginal bulb.
some pathologies in development: hypospadias is the opening of the urethra in the ventral side of the penis instead of at the glans. chryptorchism is incomplete descent of the testis due to abnormal androgen production. congenital inguinal hernia is when the intestines come through the inguinal canal into the scrotal area. hydrocele is the acculumulation of fluid in the tunica vaginalis, which covers the testis.
questions
anatomy...
1. greater and lesser pelvis separated by...
2. what is the pelvic diaphragm made of?
3. what are the four parts of the uterus?
4. what are anteversion and anteflexion?
5. what is the connective tissue that holds the uterus?
6. what are the sections of the uterine tube?
7. what is the ovary held in place by?
8. what is the broad ligament formed from?
9. what are the fornices?
10. what is the tunica albuginea?
11. leydig cells secrete...
12. sertoli cells support...
13. describe spermatogenesis. (not on test)
14. describe the pathway of the sperm out from the seminiferous tubules to the ductus deferens.
15. describe the epididymus.
16. ductus deferens transports sperm cells through...
17. what do the seminal vescicles do?
18. where do the ejaculatory ducts open into the urethra?
19. prostate gland secrete into urethra via...
20. where is the bulbourethral gland? what does it do (2)?
21. what forms the seminal fluid?
22. what are the layers to the prostate?
23. what are the zones of the prostate?
24. what zones does hypertrophy of the prostate affect?
25. what zones does prostate cancer affect?
26. what does the prostate gland secrete? (4)
26b. what is an indicator for prostate cancer?
27. where is the superficial inguinal ring?
28. where is the deep inguinal ring?
29. conjoint tendon is the lowest part of...
30a. describe the path of the spermatic cord.
30b. what is the equivalent of the spermatic cord in the female and where does it pass through?
31. what is the pampiniform plexus?
32. what is the cremaster muscle?
33. what is an inguinal hernia?
34. what is the difference between a direct and indirect inguinal hernia?
what is the analogous erectile tissue on the female:
35. penis
36. corpus cavernosum
37. corpus spongiosum
38. bulb of penis and glans penis
39. what is it that imparts turgidity during an erection?
40. describe the corpus spongiosum.
41. describe the general purpose of the ischiocavernous muscle in males and females.
42. describe the general purpose of the bulbospongiosus muscle in males and females.
43. describe the general purpose of the transverse perinei muscle in males and females.
44. what gland on females is analogous to the bulbourethral gland in males?
45. what gland on females is analogous to the prostate gland in males?
46. describe the blood supply for erectile tissue.
47. describe the nervous system's role in producing an erection.
48. what is detumescence and how does it occur?
embryology...
49. urogenital ridge is formed from...
50. germ cells arise from... and migrate to...
51. in male genital development, seminiferous tubules are formed from...
52. mesonephric duct becomes...
53. some mesonephric ducts become...
54. in female genital development, follicles are formed from...
55. describe oogonia development.
56. paramesonephric duct is formed by which hormones?
57. what does the cranial end of the paramesonephric duct grow into?
58. what does the caudal end grow into?
59. where does the sinovaginal bulb form?
60. what does the vagina form from?
61. what is uterine duplication caused by?
62. what are the characteristics of female pseudohermaphrotidism?
63. what does the genital tubercle develop into in males and females?
64. what does the urethral fold develop into in males and females?
65. what does the labioscrota develop into in males and females?
66. what is hypospadias?
67. testes descend through...
68. piece of peritoneum is retained as...
69. what is chryptorchism?
70. what is a congenital inguinal hernia?
71. what is a hydrocele?
answers
1. pelvic brim
2. levator ani+coccygeus, pudendal nerve, muscle suspended across lesser pelvis
3. body, isthmus, cervix, fundus
4. anteversion is the tilting of the uterus forward onto the bladder. anteflexion is the further bending of the uterus forward. (retroversion and retroflexion are the opposite)
5. round, transverse cervical, and uterosacral ligaments.
6. isthmus, ampula, infundibulum, ovary.
7. suspensory ligaments, ovarian ligaments
8. the parietal layer of the peritoneum that covers the reproductive organs.
9. the spaces in the vagina around the cervix.
10. the inner covering of the testis
11. testosterone
12. spermatogenesis
13. spermatogonia->spermatocytes->spermatids->mature sperm cells
14. leave the seminiferous tubule via the rete testis, which then dumps into the efferent ductules, which then converges into the epididymus, then to the ductus deferens.
15. a highly coiled tube that is 4-6 meters long, the site for sperm maturation.
16. inguinal canal
17. secretes viscous whitish-yellow fluid containing fructose
18. urethral crest of prostate.
19. prostatic ducts
20. embedded in the external urethral sphincter, lubricates penile urethra and neutralizes acid from urine. the last contributor to seminal fluid.
21. bulbourethral, seminal vescicle, prostate secretions.
22. main, submucosal, mucosal.
23. peripheral, central, transitional, periurethral. (from largest to most focused)
24. central and transitional.
25. peripheral zone.
26. prostatic acid phosphatase (PAP), fibrinolysin, citric acid, and prostate-specific antigen.
26b. increased PAP and PSA levels.
27. in the external oblique
28. in the transversalis fascia
29. transverus and internal oblique muscles
30a. through the inguinal canal and into scrotum
30b. the round ligament of the uterus, passes through inguinal canal to labia majora.
31. the venae comitantes that maintain thermoregulation in the spermatic cord.
32. the muscle innervated by genitofemoral nerve that raises the testes for thermoregulation.
33. protrusion of intestine through abdominal wall
34. direct is via a weakened conjoint tendon, indirect is through the inguinal canal.
35. clitoris
36. corpus cavernosum
37. labia minora
38. bulb of vestibule and glans clitoris
39. the tunica albuginea
40. separated by the vagina in females but surrounds the urethra in males. has less CT, therefore less turgidity.
41. overlies corpus cavernosus
42. overlies bulb of penis/vestibule
43. tauten perineal membrane
44. greater vestibular
45. urethral and paraurethral
46. internal iliac artery to internal pudendal artery to deep artery of the penis/clitoris
47. during erection, parasympathetic nerves (S2,3,4) dilate helicine arteries and allow blood to flow into erectile tissue
48. sympathetic nervous activity constricts helicine arteries and reroutes blood into venous plexus and deep dorsal vein.
49. intermediate mesoderm
50. yolk sac and gonad
51. sex cords
52. ductus deferens, seminal vesicles, ejaculatory duct.
53. efferent ductules
54. sex cords which form cortical cords, which form follicles.
55. oogonia form from germ cells, and undergo mitosis during fetal development. after birth no more oogonia are formed.
56. maternal or placental estrogens.
57. uterine tubes, ending in infundibulum that opens up into peritoneum.
58. uterus and vagina
59. where the paramesonephric ducts fuse with the urogenital sinus
60. the fusion of the bulbs, which begin to hollow out.
61. improper fusion or development of paramesonephric ducts.
62. masculinization of female external genitalia: partial fusion of labia majora, clitoral hypertrophy, and persistent urogenital sinus.
63. penis and clitoris
64. penile urethra and labia minora
65. scrotum and labia majora.
66. urethral openings on the ventral surface of the penis rather than at the glans.
67. inguinal canal, along gubernaculum.
68. tunica vaginalis
69. abnormal androgen production produces undescended testes.
70. patency of inguinal canal which allows intestines to enter scrotum
71. excess fluid in the tunica vaginalis.
Showing posts with label reproduction. Show all posts
Showing posts with label reproduction. Show all posts
Tuesday, February 10, 2009
Sunday, November 23, 2008
histology: male reproductive system
this unit looks at the male reproductive system, focusing on spermiogenesis and the tubular architecture out to the penis. spermiogenesis occurs in the seminiferous tubules of the testis, which are covered on the outside by the tunica vaginalis layer, which is an invagination of the parietal peritoneum, followed by a thick CT tunica albuginea layer which sends CT partitions inwards, dividing the testis into lobes with 1-4 seminiferous tubules each. inside the seminiferous tubules, which are approximately 200um in diameter and 50cm long (but highly convoluted), spermiogenesis begins: type a spermatogonia are the undifferentiated stem cells that reside near the edges of the seminiferous tubules and provide a reserve of potential sperm cells. type b spermatogonia are the cells that have begun differentiating into spermatocytes. spermatocytes begin the process of meoisis, whereby the cell divides into two and halves its chromosomes-- primary spermatocytes are "4N" and secondary spermatocytes are "quasi 2N" that have undergone the first meotic division. spermatids are spermatocytes that have completed meoitic division and are now ready for morphological differentiation. spermatozoans are completed sperm cells that have been morphologically differentiated for swimming and fertilization. thus the order is type a spermatogonia => type b spermatogonia => primary spermatocyte => secondary spermatocyte => spermatid => spermatozoan.
the spermatozoans then swim out of the seminiferous tubules into a series of converging tubules out of the testis into the ductus epididymus, which is a singularly convoluted tubule (50 meters long scrunched up into 50cm) which serves as a maturation and storage site for the spermatozoans, as well as absorbing any excess fluids from spermiogenesis. it then flows upwards through a tube called the ductus deferens, which is straight and has a much thicker muscularis layer (inner longitudinal, middle circular, outer longitudinal) which is responsible for the peristaltic waves during ejaculation. after passing through the prostatic region, the ductus deferens changes into the urethra, which is a common pathway for the urinary and reproductive tract. it is housed in the corpus spongiosum on the dorsal side of the penis, which is one of the three fibroelastic erectile tissues- the other two being two columns of corpus cavernosum on the ventral side. as the urethra goes from the prostatic region to the tip of the penis, it undergoes epithelial transitions from transitional to stratified columnar to stratified squamous.
questions
1. how long does spermatogenesis take to complete and how many sperm are produced per day?
2. where does spermatogenesis take place?
3. what is the testis covered by?
4. describe the rough dimensions of a seminiferous tubule.
5. what are spermatogonia? what are type a and type b spermatogonia?
6. what are spermatocytes? what are primary and secondary spermatocytes?
7. what are spermatids?
8. what are spermatozoans?
9. what are Leydig's cells?
10. what is the ductus epididymis? what is its function?
11. what are the layers of the ductus epididymus?
12. what is the ductus deferens?
13. what are the layers of the ductus deferens?
14. what are the accessory glands?
15. what is erectile tissue?
16. what are the three columns of erectile tissue in the penis?
17. describe the epithelial transitions in the urethra.
answers
1. 75 days, 200,000 sperm produced per day
2. in the stratified cuboidal epithelium of the seminiferous tubules in the testis.
3. tough CT layer called tunica albuginea which sends partitions inwards to form lobules, and a tunica vaginalis on the outside, which is an invagination of the parietal peritoneum.
4. 200um diameter pipe, about 50cm long
5. reserve cells that pool along the back of the seminiferous tubules. type a are stem cells that maintain the stock and type b differentiate into spermatocytes.
6. spermatocytes are spermatogonia that have begun meiotic division, moving towards the lumen of the tubule as they divide. primary spermatocytes are 4N and secondary spermatocytes are quasi-2N cells that have undergone the first meiotic division.
7. spermatids are haploid (2N) cells and are ready to morphologically differentiate.
8. spermatozoans are sperm cells that have completed spermiogenesis and is now specialized morphologically for swimming and fertilization.
9. special endocrine cells within the between the seminiferous tubules that secrete testosterone, promoting spermatogenesis and secondary sex characteristics.
10. the long convoluted duct that leads out of the testis and serves as a maturation / storage site for spermatozoa, and absorbs excess fluids from spermatogenesis.
11. the layers are: PSCC, thin CT lamina propria, muscularis, serosa.
12. the thick, muscular tube leading from the epididymus back to the body which is responsible for the peristaltic waves during ejaculation.
13. PSCC, lamina propria (thin CT, rich in elastic fibers), thick and well developed muscularis (with inner longitudinal, middle circular, outer longitudinal layers), and adventitia.
14. glands that promote sperm survival and transport by adding "seminal fluids", such as the seminal vescicle and prostate.
15. fibroelastic CT mixed with endothelially lined spaces that can accumulate blood.
16. 2 dorsal columns of corpus cavernosum and 1 ventral column of corpus spongiosum.
17. in the prostatic area there is a change from transitional epithelium to stratified columnar, and near tip of the penis another change to stratified squamous.
the spermatozoans then swim out of the seminiferous tubules into a series of converging tubules out of the testis into the ductus epididymus, which is a singularly convoluted tubule (50 meters long scrunched up into 50cm) which serves as a maturation and storage site for the spermatozoans, as well as absorbing any excess fluids from spermiogenesis. it then flows upwards through a tube called the ductus deferens, which is straight and has a much thicker muscularis layer (inner longitudinal, middle circular, outer longitudinal) which is responsible for the peristaltic waves during ejaculation. after passing through the prostatic region, the ductus deferens changes into the urethra, which is a common pathway for the urinary and reproductive tract. it is housed in the corpus spongiosum on the dorsal side of the penis, which is one of the three fibroelastic erectile tissues- the other two being two columns of corpus cavernosum on the ventral side. as the urethra goes from the prostatic region to the tip of the penis, it undergoes epithelial transitions from transitional to stratified columnar to stratified squamous.
questions
1. how long does spermatogenesis take to complete and how many sperm are produced per day?
2. where does spermatogenesis take place?
3. what is the testis covered by?
4. describe the rough dimensions of a seminiferous tubule.
5. what are spermatogonia? what are type a and type b spermatogonia?
6. what are spermatocytes? what are primary and secondary spermatocytes?
7. what are spermatids?
8. what are spermatozoans?
9. what are Leydig's cells?
10. what is the ductus epididymis? what is its function?
11. what are the layers of the ductus epididymus?
12. what is the ductus deferens?
13. what are the layers of the ductus deferens?
14. what are the accessory glands?
15. what is erectile tissue?
16. what are the three columns of erectile tissue in the penis?
17. describe the epithelial transitions in the urethra.
answers
1. 75 days, 200,000 sperm produced per day
2. in the stratified cuboidal epithelium of the seminiferous tubules in the testis.
3. tough CT layer called tunica albuginea which sends partitions inwards to form lobules, and a tunica vaginalis on the outside, which is an invagination of the parietal peritoneum.
4. 200um diameter pipe, about 50cm long
5. reserve cells that pool along the back of the seminiferous tubules. type a are stem cells that maintain the stock and type b differentiate into spermatocytes.
6. spermatocytes are spermatogonia that have begun meiotic division, moving towards the lumen of the tubule as they divide. primary spermatocytes are 4N and secondary spermatocytes are quasi-2N cells that have undergone the first meiotic division.
7. spermatids are haploid (2N) cells and are ready to morphologically differentiate.
8. spermatozoans are sperm cells that have completed spermiogenesis and is now specialized morphologically for swimming and fertilization.
9. special endocrine cells within the between the seminiferous tubules that secrete testosterone, promoting spermatogenesis and secondary sex characteristics.
10. the long convoluted duct that leads out of the testis and serves as a maturation / storage site for spermatozoa, and absorbs excess fluids from spermatogenesis.
11. the layers are: PSCC, thin CT lamina propria, muscularis, serosa.
12. the thick, muscular tube leading from the epididymus back to the body which is responsible for the peristaltic waves during ejaculation.
13. PSCC, lamina propria (thin CT, rich in elastic fibers), thick and well developed muscularis (with inner longitudinal, middle circular, outer longitudinal layers), and adventitia.
14. glands that promote sperm survival and transport by adding "seminal fluids", such as the seminal vescicle and prostate.
15. fibroelastic CT mixed with endothelially lined spaces that can accumulate blood.
16. 2 dorsal columns of corpus cavernosum and 1 ventral column of corpus spongiosum.
17. in the prostatic area there is a change from transitional epithelium to stratified columnar, and near tip of the penis another change to stratified squamous.
Wednesday, November 19, 2008
histology: female reproductive system
this section covered the basic anatomy of the female reproductive system and follows the life of a oocyte from its creation until implantation in the uterus. the ovaries start with ~400,000 oocytes at puberty, out of which 400 are ovulated. the process begins in the ovaries, which are masses of mainly connective tissue, surrounded by a simple cuboidal germinal epithelium and tunica albuginea connective tissue layer. inside the ovaries are many "follicles" at varying stages of development. each follicle begins as a primordial follicle, which is an oocyte (~30um) surrounded by simple cuboidal follicular cells. the next stage is a primary follicle, where a slightly larger oocyte (50um) is surrounded by a cuboidal follicular layer that begins to stratify, and a light pink zona pelucida appears around the oocyte. the next stage is a secondary follicle, with a larger oocyte (~100um), the beginning of the development of an "antrum", which is a space in the follicle that is filled with follicular liquor, and the emergence of the theca, which is a double layered perimeter in the follicular layer that has two parts: the theca interna, which secretes estrogen, and the theca extra, which is made up of connective tissue and smooth muscle. the next and final phase is the tertiary, or graafian, or mature follicle, in which the larger oocyte is surrounded by a nest of follicular cells, the antrum makes up the bulk of the follicle and nearly pinches off the oocyte, and the entire follicular diameter approaches 10-12 mm.
at this point the tertiary follicle releases its oocyte from the ovaries (the released oocyte is now an ovum) and the ovum begins to travel down the oviduct. the oviduct contains many epithelial folds of ciliated simple columnar mucosa, with a muscularis composed of an inner circular layer and outer longitudinal layer, and an outer serosa layer. around the 2nd day after the release of the ovum, it can be fertilized in the upper 1/3 of the oviduct, called the ampula. it then travels down to the uterus for implantation, which generally occurs ~7 days later. the uterus has three layers: endometrium, myometrium, and perimetrium. the myometrium is made of smooth muscle and perimetrium is the serosa; neither of these layers change much during the menstrual cycle. contrast this with the endometrium, which undergoes dramatic growth and breakdown during the menstrual cycle, beginning with the menstrual phase, then the follicular / proliferative phase, then the progestational or secretory phase, then the gravis phase. the endometrium is broken down into two functional layers: the stratum basale, which stays the same during the cycle, and the stratum functionale, which is the layer that builds up and degenerates. while the follicle is developing in the ovaries the endometrium is building up a highly vascularized tissue in preparation for implantation. if implantation does not occur, then the stratum functionale breaks down during the "menstrual phase".
below the uterus is the cervix, which is the opening to the vagina. the transition from the cervix to the vagina happens dramatically, changing swiftly from the simple columnar epithelium in the cervix to the stratified squamous of the vagina. the vagina has 3 layers, the top layer being mostly parakeratinized stratified squamous, with a chaotically organized muscularis underneath, and an adventitia layer beyond.
one other note: the corpeus luteum is the remnant of the tertiary follicle after the ovum is released from the ovaries. if pregnancy does occur, the corpeus luteum continues to enlarge in the ovaries and secrete estrogen (which helps the development and growth of sex organs) and progesterone (which prepares the uterus for pregnancy and the mammary glands for lactation) for ~10 weeks or until the placenta takes over. if pregnancy does not occur, then the corpeus luteum breaks down in 12-14 days and forms a whitish mass called the corpeus albicans.
questions
1. how does oogenesis affect production of hormones?
2. describe the physical makeup of the ovary.
3. how many oocytes do the ovaries start with at puberty and about how many are ovulated in total?
4. describe the primordial follicle.
5. what is the development of the primordial follicle mediated by?
6. what are atretic follicles?
7. describe the primary follicle.
8. describe the secondary follicle.
9. what is follicular liquor and what does it develop into?
10. what is theca and what are the two layers?
11. describe the tertiary follicle.
12. what is the corpeus luteum and what does it do?
13. what is the name for the structure that the corpeus luteum degenerates into?
14. what are the physical characteristics of the oviduct?
15. what are the three layers of the uterus?
16. what are the physical characteristics of the endometrium?
17. what are the phases of the menstrual cycle?
18. describe the timing of fertilization and implantation after the ovum is released from the ovaries.
19. what is histologically unique about the transition from the cervix to the vagina?
20. what are the layers of the vagina?
answers
1. oogenesis produces estrogen to promote growth and development of sex organs, progesterone to prepare uterus for pregnancy and mammary glands for lactation.
2. mostly connective tissue with follicles in varying stages of development. covered by germinal epithelium (simple cuboidal) and the tunica albuginea (CT) layer.
3. 400,000 and 400
4. an oocyte enclosed in a squamous layer of follicular cells, about 30um
5. FSH (follicle stimulating hormone)
6. follicles in the ovaries that have degenerated
7. a larger oocyte (50um) surrounded by cuboidal follicular cells, with a pink zona pellucida developing around the oocyte.
8. an even larger oocyte (100um) surrounded by stratified cuboidal follicular cells, up to 1-2mm total diameter
9. the secretions from follicular cells in a secondary follicle that develop into an antrum.
10. theca is a double layered perimeter that appears in the secondary follicle. the theca interna has estrogen secreting cells and the theca externa is CT and smooth muscle.
11. the tertiary, or mature, or graafian follicle is up to 10mm in total diameter with a huge antrum and the oocyte surrounded by a nest of follicular cells.
12. the corpeus luteum is a temporary structure that is formed from the remains of the tertiary follicle which rapidly proliferates to secrete progesterone and estrogen. if pregnancy occurs, the corpeus luteum continues to enlarge and secretes estrogen and progesterone until the placenta takes over. if pregnancy does not occur, then the corpeus luteum degenerates in 12-14 days.
13. corpus albicans
14. has a mucosa, muscularis, and serosa layers. mucosa has many folds with simple columnar epithelium, with cilia, some secretory cells (to provide nutrients for ova) and lamina propria. muscularis has inner circular and outer longitudinal smooth muscle.
15. endometrium, myometrium (muscularis), perimetrium (serosa).
16. simple columnar epithelium, simple tubular uterine glands, stratum basalis/stratumfunctionalis.
17. the menstrual phase, the follicular or proliferative phase, the progestational or secretory phase, and the gravid phase.
18. fertilization occurs in the ampula (upper 1/3) of the oviduct ~2 days after the ovum is released from the ovaries, and implantation generally happens ~7 days later.
19. the transition from the cervix to the vagina occurs dramatically, changing from simple columnar to stratified squamous epithelium within a single layer of cells.
20. stratified squamous epithelium (mostly parakeratinized), lamina propria with elastic fibers, muscularis (poorly organized), adventitia.
at this point the tertiary follicle releases its oocyte from the ovaries (the released oocyte is now an ovum) and the ovum begins to travel down the oviduct. the oviduct contains many epithelial folds of ciliated simple columnar mucosa, with a muscularis composed of an inner circular layer and outer longitudinal layer, and an outer serosa layer. around the 2nd day after the release of the ovum, it can be fertilized in the upper 1/3 of the oviduct, called the ampula. it then travels down to the uterus for implantation, which generally occurs ~7 days later. the uterus has three layers: endometrium, myometrium, and perimetrium. the myometrium is made of smooth muscle and perimetrium is the serosa; neither of these layers change much during the menstrual cycle. contrast this with the endometrium, which undergoes dramatic growth and breakdown during the menstrual cycle, beginning with the menstrual phase, then the follicular / proliferative phase, then the progestational or secretory phase, then the gravis phase. the endometrium is broken down into two functional layers: the stratum basale, which stays the same during the cycle, and the stratum functionale, which is the layer that builds up and degenerates. while the follicle is developing in the ovaries the endometrium is building up a highly vascularized tissue in preparation for implantation. if implantation does not occur, then the stratum functionale breaks down during the "menstrual phase".
below the uterus is the cervix, which is the opening to the vagina. the transition from the cervix to the vagina happens dramatically, changing swiftly from the simple columnar epithelium in the cervix to the stratified squamous of the vagina. the vagina has 3 layers, the top layer being mostly parakeratinized stratified squamous, with a chaotically organized muscularis underneath, and an adventitia layer beyond.
one other note: the corpeus luteum is the remnant of the tertiary follicle after the ovum is released from the ovaries. if pregnancy does occur, the corpeus luteum continues to enlarge in the ovaries and secrete estrogen (which helps the development and growth of sex organs) and progesterone (which prepares the uterus for pregnancy and the mammary glands for lactation) for ~10 weeks or until the placenta takes over. if pregnancy does not occur, then the corpeus luteum breaks down in 12-14 days and forms a whitish mass called the corpeus albicans.
questions
1. how does oogenesis affect production of hormones?
2. describe the physical makeup of the ovary.
3. how many oocytes do the ovaries start with at puberty and about how many are ovulated in total?
4. describe the primordial follicle.
5. what is the development of the primordial follicle mediated by?
6. what are atretic follicles?
7. describe the primary follicle.
8. describe the secondary follicle.
9. what is follicular liquor and what does it develop into?
10. what is theca and what are the two layers?
11. describe the tertiary follicle.
12. what is the corpeus luteum and what does it do?
13. what is the name for the structure that the corpeus luteum degenerates into?
14. what are the physical characteristics of the oviduct?
15. what are the three layers of the uterus?
16. what are the physical characteristics of the endometrium?
17. what are the phases of the menstrual cycle?
18. describe the timing of fertilization and implantation after the ovum is released from the ovaries.
19. what is histologically unique about the transition from the cervix to the vagina?
20. what are the layers of the vagina?
answers
1. oogenesis produces estrogen to promote growth and development of sex organs, progesterone to prepare uterus for pregnancy and mammary glands for lactation.
2. mostly connective tissue with follicles in varying stages of development. covered by germinal epithelium (simple cuboidal) and the tunica albuginea (CT) layer.
3. 400,000 and 400
4. an oocyte enclosed in a squamous layer of follicular cells, about 30um
5. FSH (follicle stimulating hormone)
6. follicles in the ovaries that have degenerated
7. a larger oocyte (50um) surrounded by cuboidal follicular cells, with a pink zona pellucida developing around the oocyte.
8. an even larger oocyte (100um) surrounded by stratified cuboidal follicular cells, up to 1-2mm total diameter
9. the secretions from follicular cells in a secondary follicle that develop into an antrum.
10. theca is a double layered perimeter that appears in the secondary follicle. the theca interna has estrogen secreting cells and the theca externa is CT and smooth muscle.
11. the tertiary, or mature, or graafian follicle is up to 10mm in total diameter with a huge antrum and the oocyte surrounded by a nest of follicular cells.
12. the corpeus luteum is a temporary structure that is formed from the remains of the tertiary follicle which rapidly proliferates to secrete progesterone and estrogen. if pregnancy occurs, the corpeus luteum continues to enlarge and secretes estrogen and progesterone until the placenta takes over. if pregnancy does not occur, then the corpeus luteum degenerates in 12-14 days.
13. corpus albicans
14. has a mucosa, muscularis, and serosa layers. mucosa has many folds with simple columnar epithelium, with cilia, some secretory cells (to provide nutrients for ova) and lamina propria. muscularis has inner circular and outer longitudinal smooth muscle.
15. endometrium, myometrium (muscularis), perimetrium (serosa).
16. simple columnar epithelium, simple tubular uterine glands, stratum basalis/stratumfunctionalis.
17. the menstrual phase, the follicular or proliferative phase, the progestational or secretory phase, and the gravid phase.
18. fertilization occurs in the ampula (upper 1/3) of the oviduct ~2 days after the ovum is released from the ovaries, and implantation generally happens ~7 days later.
19. the transition from the cervix to the vagina occurs dramatically, changing from simple columnar to stratified squamous epithelium within a single layer of cells.
20. stratified squamous epithelium (mostly parakeratinized), lamina propria with elastic fibers, muscularis (poorly organized), adventitia.
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