BIO211 Weekly Guide #10
REPRODUCTIVE
SYSTEMS
After completing this laboratory you should be able to:
1) Identify the major reproductive organs of the male and female
2) Identify the testes, epididymis, and vas deferens in histological sections and describe the substructure of each
3) Identify the ovary, oviducts (Fallopian tubes), uterus, and breast in histological sections and describe the substructure of each
4) Describe in some detail the hormonal control of testicular maturation and spermatogenesis in the male
5) Describe in some detail the hormonal control of ovarian maturation, the ovulatory cycle, the menstrual cycle, pregnancy, parturition (birth), and lactation in the female
Guide to Gross Anatomy Guide to Histology Guide to Physiology
Outline
I. Reproductive systems overview [FAP 28-1]
A. Essential reproductive organs
male - testes
female - ovaries
functions:
produce gametes (germ cells)
produce hormones (other cells)
B. Accessory reproductive organs
male - scrotum, ducts, glands, penis
female - oviducts, uterus, vagina, vulva, mammary glands
fetus & mother - fetoplacental unit
functions:
transport and maintenance of gametes (male & female)
copulation (male & female)
maintenance of zygote/fetus (female)
birth route (female)
maintenance of baby (female)
"temporary" endocrine "glands" (female & fetus)
II. Male [FAP 28-2]
A. Testes
location - within scrotum
size - 3 cm. x 1 cm., egg shaped
structure:
cover - tunica vaginalis (peritoneal remnant), tunica albuginea (capsule)
stroma - septae, lobules
tubular system:
seminiferous tubules
1-3 per lobule
highly coiled loops
cell types:
Sertoli cells - support and nourishment
spermatogonia --> spermatocytes --> spermatids --> sperm
interstitial (Leydig) cells - produce testosterone
hormonal actions [FAP Spotlight Fig 28-12]
FSH --> Sertoli cells, spermatogonia - promotes spermatogenesis
LH (ICSH) --> Leydig cells - increases testosterone production
tubuli recti - straight portions of seminiferous tubules
rete testis - network of interconnected tubules
simple cuboidal ciliated epithelium
ductuli efferentes - straight tubes
simple columnar, some ciliated cells
epididymis - long, highly coiled tube
pseudostratified columnar epithelium with stereocilia
sperm storage and maturation
B. Ductus (vas) deferens
pseudostratified columnar epithelium with stereocilia
very muscular
transport sperm to ejaculatory ducts
C. Ejaculatory ducts - run through prostate and connect to prostatic urethra
D. Accessory glands - produce semen
seminal vesicles - outpocketings of vas deferens
prostate - complex network of ducts
bulbourethral (Cowper's) glands - empty into membranous urethra
E. Urethra - shared with urinary system
prostatic urethra - transitional epithelium
membranous urethra - columnar epithelium (stratified or pseudostratified)
cavernous (penile) urethra columnar epi --> stratified squamous moist epithelium
F. External genitalia
scrotum - homologous with labia majora
penis - homologous with clitoris
3 erectile bodies - corpora cavernosa, corpus spongiosum
glans
prepuce (foreskin)
III. Female [FAP 28-3]
A. Ovaries
location
size - almond size and shape
structure:
cover - germinal epithelium, tunica albuginea
stroma
hilum
medulla - loose C.T., smooth muscle
cortex - follicles
follicle life history
primordial - primary oocyte & flattened cells
primary - enlarged oocyte, zona pellucida, zona granulosa, theca
secondary - oocyte, cumulus oophorus, granulosa, antrum, theca interna,
theca externa
Graafian - secondary oocyte, corona radiata, theca interna, theca externa
ovulation:
follicle ruptures --> ovum expelled --> follicle collapses
corpus luteum formation
blood clot forms
proliferation of granulosa cells
vascular invasion
corpus luteum growth (if fertilization)
involution --> forms corpus albicans (if no fertilization)
follicular atresia
hormonal sources, actions, and controls [FAP Spotlight Fig 28-24]
gonadotropin releasing hormone (GnRH) --> release of FSH, LH
follicle stimulating hormone (FSH) --> follicular development
lutenizing hormone (LH) --> ovulation, maintains corpus luteum
human chorionic gonadotrophin (HCG) --> maintains corpus luteum
estrogen --> developmental, maintenance, and behavioral effects
progesterone--> " " " " "
B. Oviducts (fallopian tubes, uterine tubes)
regions:
isthmus, ampulla, infundibulum, fimbria
wall - 3 layers:
mucosa - simple col. epi. (1/2 of cells are ciliated), lamina propria
muscularis - smooth muscle - inner circular, outer longitudinal rings
serosa - fold of visceral peritoneum
C. Uterus
regions:
fundus, body, cervix, internal os, external os
wall - 3 layers:
endometrium - simple columnar epithelium
lamina propria - vascular, glands
cycle (menstruation)
myometrium - thick, muscular, vascular
smooth muscle and fibroelastic C.T.
serosa
D. Vagina
extends from cervix to vaginal opening
wall - 3 layers:
mucosa - stratified squamous non-keratinized
muscularis - smooth muscle
adventicia
E. External genitalia (vulva)
mons pubis, labia majora, labia minora, clitoris
stratified squamous keratinized epithelium
lots of nerve endings
F. Mammary glands (breasts)
structure: branched tubuloalveolar glands (modified sweat glands), adipose
alveoli <-- estrogen and progesterone maintain
ducts <-- estrogen maintains
myoepithelial cells <-- oxytocin stimulates
product: milk
milk proteins, lipids, lactose, immunoglobulins
prolactin --> milk production
oxytocin --> milk ejection
Gross Anatomy List
Female: Male:
ovaries scrotum
ovarian arteries & veins testes
oviducts (fallopian tubes) epididymus
infundibulum & fimbriae spermatic cords
ampulla spermatic arteries & veins
isthmus ductus deferens (vas deferens)
uterus seminal vesicles
body prostate gland
fundus urethra - prostatic, membranous, penile
cervix penis
ligaments: glans penis
broad ligament of the uterus prepuce (foreskin)
mesosalpinx corpora cavernosa penis
mesometrium corpus spongiosum penis
mesovarium
round ligament of the uterus
ovarian ligament
suspensory ligament of the ovary
recto-uterine pouch
vagina
mons pubis Related Structures:
labia majora inguinal canal
labia minora internal inguinal ring
clitoris external inguinal ring
vaginal orifice
urethral orifice
mammary glands (breasts)
nipples
areola
perineum
Key: Know location, function, and male-female homologies
Guide to Gross Anatomy
The reproductive system consists of the essential organs - the testes (male) or ovaries (female), and the accessory organs - the internal and external genitalia. The testis and the ovary are developmental homologues, in that they develop from the same undifferentiated structure - the gonad. The external genitalia and accessory glands are also homologous structures in the male and female, however, the internal ducts are not .
Since the male system is simpler anatomically and much simpler physiologically, we will explore it first.
Male Reproductive Organs [APL Exercise 27-2]
[FAP Figs 28-1 to 28-4, 28.11; APL Figs 27.3 to 27.6]
The male reproductive system consists of the testes, the vas (ductus) deferens, the urethra, the accessory glands, the scrotum, and the penis.
a) Locate the scrotum in the models and charts. Identify the following structures:
scrotal raphe tunica vaginalis epididymis
testis appendix of the testis
- The adult testis produces two hormones, testosterone and inhibin. Review the functions of these hormones. What is the other major "product" of the testis which becomes part of the semen?
- What is the function of the epididymis?
- Of what structure is the tunica vaginalis a remnant?
- The scrotal raphe looks like a seam because it is one. It marks the fusion of the embryonic urethral fold.
b) Trace the course of the vas deferens from the epididymis to the prostate.
- How does the vas deferens enter the abdominal cavity? What circulatory and muscular structures pass with it in the spermatic cord?
- Study the relationship of the vas deferens to the ureter in the region of the bladder and prostate gland.
c) Locate the prostate gland on the models and charts. It lies against the posterio-inferior surface of the bladder. Locate the seminal vesicles lateral to the point of entry of the vas deferens. Locate the bulbourethral (Cowper's) glands adjacent to the membranous urethra (if possible).
- What is the function of these glands, i.e. what do they contribute to the semen?
d) Study the penis in the models and charts. Locate the following structures:
shaft prepuce (if there) corpus spongiosum
glans corpora cavernosa cavernous (penile) urethra
- What happens to the corpora cavernosa and the corpus spongiosum during an erection?
- What is removed by a circumcision?
Female Reproductive Organs [APL Exercise 27-2]
[FAP Figs 28-13 to 28-23; APL Figs 27.8 to 27.10]
The female reproductive system consists of the ovaries, the fallopian tubes, the uterus, the accessory glands, the labia, and the clitoris. The mammary glands and placenta may also be considered as accessory reproductive organs. The internal genitalia are located posterior to the bladder and are held in place by the broad ligament, a fold of the peritoneum.
a) Locate the ovaries in the models and charts. Locate the following ligaments which hold each ovary in place:
mesovarium ovarian ligament suspensory ligament
- To what other structure does each of these ligaments attach the ovary?
- In addition to the ova, the ovaries produce the hormones estrogen, progesterone, and inhibin. Review the function of each of these hormones. It is extremely important to recognize that control of these hormones is cyclic. You should understand how this cycle comes to be, and how the relative hormonal levels of the gonadal and pituitary hormones vary with follicular development in the ovary.
- Note that when an ovarian follicle ruptures, the ovum is usually shed into the peritoneal cavity.
b) Locate the fallopian tubes (uterine tubes) in the models and charts. Identify the following regions:
fimbria ampulla
infundibulum isthmus
- Note that the infundibulum opens onto the inside of the peritoneal cavity. This means that the peritoneal cavity is not completely enclosed in the female, but is actually continuous with the outside, via the fallopian tubes, uterus, and vagina.
- What mechanism propels the ovum along the fallopian tube? Where does fertilization usually take place?
c) Locate the uterus in the models and charts. Identify the following regions and structures:
fundus external os round ligament of the ovary
body broad ligament vesicouterine pouch
cervix mesosalpinx rectouterine pouch
internal os mesometrium
- Review the changes that take place in the uterine lining during the menstrual cycle. How do these correspond to follicular changes in the ovary and hormonal levels of estrogen and progesterone?
- Familiarize yourself with the relationship of the broad ligament to the peritoneum and the other ligaments of the internal genitalia. Where does the round ligament of the uterus run?
- Study the chart of the changes that take place in the size, shape, and location of the uterus during the course of pregnancy. What hormone causes contraction of the uterine muscles during parturition (birth). What is the "positive feedback" that stimulates this hormone? The recovery of the uterus to nearly its original size takes place within a few hours of parturition, which is quite a remarkable feat.
d) Study the region of the perineum of the female. Locate the following structures:
mons pubis vestibule vagina
labia majora urethral orifice obstetrical perineum
labia minora hymen anus
clitoris
- Describe the relationship of the vagina to the urethra, the rectum, and the muscles of the pelvic floor.
- What is the function of the accessory glands (Bartholin's glands) in the female?
- What are the male homologues of the labia majora, labia minora, and clitoris?
e) The placenta is an organ of pregnancy that has components derived from tissue of both the mother and the fetus. It functions as an interface between the maternal and fetal circulatory systems.
- The placenta also acts as an endocrine gland whose relative contribution increases throughout pregnancy. By the third trimester it is virtually self-sustaining. With the help of the fetal adrenals it produces estrogen and progesterone. It also produces human chorionic gonadotrophin (HCG - an LH analog) and human placental lactogen (HPL - a prolactin analog).
f) Study the mammary glands (breasts) on the models and charts. Locate the areola.
- What is the function of these glands? What hormones control development, milk production, and milk letdown?
- Why do you suppose that it is clinically important to know the general pattern of lymphatic drainage of the mammary breast?
Guide to Histology
Male Reproductive System [APL Exercise 27-1]
The male reproductive system has the relatively simple functions of sperm production and insemination. After working through the slides of the male reproductive system you should be able to:
1) Trace the life history and travels of a single spermatozoan from production in the seminiferous tubules to ejaculation via the urethra.
2) Recognize the testis, epididymis, and vas deferens in histological section.
3) Briefly describe the hormonal control of male development and sperm production.
In the slides of the male reproductive system observe the following:
a) Testis and Epididymis [FAP Figs 28-4, 28-5, 28-9; ALP Figs 27.13, 27.14]
The seminiferous tubules of the testis may be recognized by their highly coiled structure (which results in repeated, closely packed sections through each tubule) , the complex stratified epithelium, and the presence of sperm in the lumens. The epididymis may be recognized by its highly coiled form and the presence of stereocilia on the epithelial surface.
- In these slides identify the seminiferous tubules. Although the epithelial lining of the tubules looks rather complex, it consists of just two cell lineages. These are the smaller germinal cells (spermatogonia, spermatocytes, and spermatids) and larger, columnar support cells, called Sertoli cells.
- Trace the stages that the male gametes go through in developing from spermatogonia to spermatozoa. Note that the spermatozoa in the lumen are mostly positioned with their heads burrowed into the epithelial surface and their tails protruding.
- Locate a Sertoli cell by its characteristic oblong nucleus. Note that Sertoli cells actually extend from the basal lamina to the luminal surface of the epithelium, and envelop all stages of maturing germ cells as they work their way to the surface.
- Locate the interstitial cells of Leydig in the spaces between seminiferous tubules. What hormone do these cells produce?
- How would you classify the epithelium of the epididymis? Contrast the appearance of this epithelium to that of the seminiferous tubules. What is the function of the epididymis? What role do the stereocilia play in this?
b) Spermatic Cord
The vas deferens (ductus deferens) may be recognized by its pseudostratified columnar epithelium with stereocilia. In contrast to the epididymis, the vas deferens has thick muscular walls, and will typically not appear in multiple sections within the same slide.
- Identify the vas deferens and distinguish it from the artery and vein (if present), which are also seen in sections through the spermatic cord.
- Classify the epithelium. How many muscle layers are in the vas deferens?
- What nerve and what blood vessels accompany the vas deferens in the spermatic cord? Review its path from the scrotum to the abdominal cavity.
Female Reproductive System [APL Exercise 27-2]
The female reproductive system is much more complex than that of the male, reflecting its multiple roles in ovum production and transport, sperm collection and maintenance, fertilization, fetal maintenance and parturition, and nourishment of the suckling infant. After working through the slides on the female reproductive system you should be able to:
1) Trace the life history and travels of an ovum from production in the ovary to possible
fertilization in the oviduct and implantation in the uterine wall.
2) Recognize the ovary, oviduct, uterus, vagina, and breast in histological section.
3) Briefly describe the hormonal control of female development, the ovarian and
uterine cycles, pregnancy, the birth process, and lactation.
In the slides of the female reproductive structures, observe the following:
a) Ovary [FAP Fig 28-14, 28-16; APL Figs 27.17, 27.18]
The ovary is distinguished by the presence of its characteristic follicles, in various stages of development. Note that the slide does not depict a human ovary, which would not have all stages present at once.
- Identify the cortex and medulla of the ovary. Scan the slide to locate and identify primordial follicles, primary follicles, secondary follicles, and Graafian follicles.
- Identify the "germinal" epithelium". Note that the germinal epithelium is neither germinal nor an epithelium.
- What structural features distinguish the various stages in follicular development? Specifically identify the ovum, antrum, cumulus oöphorus, corona radiata, granulosa, theca interna, theca externa.
- Try to identify atretic follicles. Note that this is the fate of the vast majority of follicles - they degenerate, involute, and are replaced by C.T. without ever reaching maturity.
- Try also to locate a corpus luteum. What is the origin and what is the function of this structure? Try to locate a corpus albicans.
- Review the control of follicular development by hormones of the anterior pituitary. What cells of the ovarian follicle produce estrogen and progesterone?
b) Oviduct [FAP Fig 28-17]
The oviduct (Fallopian tube) may be recognized in cross section by the incredibly convoluted lumen, with its characteristic epithelium containing both ciliated and non-ciliated (brush border) cells.
- Study the oviduct on demonstration and classify its epithelium. What is the function of the cilia? In which direction do they beat?
- The non-ciliated cells have microvilli on their apical surface. What do you suppose is the function of the these non-ciliated cells?
c) Uterus [FAP Figs 28-19, 28-20]
The uterus may be recognized by its thick muscular walls, highly vascular lamina propria with convoluted spiraling arteries and venous "lakes", and deep endometrial glands.
- Identify the endometrium, myometrium, and perimetrium. Trace the changes that occur in the endometrium over the course of the menstrual cycle. How are these changes under hormonal control?
- What hormone has the myometrium as one of its target organs? How does pressure on the internal os of the cervix initiate a "positive feedback loop" on release of this hormone? What event or process breaks this loop?
d) Vagina [FAP Fig 28-21]
The vagina has thick, muscular walls and is lined with nonkeratinized stratified squamous epithelium.
- How is this epithelium appropriate for its function? Are there glands to lubricate the vagina? Is its muscle striated or smooth? How would you distinguish the vagina from the esophagus in histological section?
e) Breast [FAP Fig 28-23]
The breast may be recognized in histological section by the alveolar structure of the lactiferous glands, and the quantity of adipose tissue in surrounding C.T.
- Identify alveoli, ducts, and fat cells. Distinguish intralobular from interlobar connective tissue.
- Review the hormonal control of breast development, milk production, and milk letdown. How would you expect the microscopic appearance of the breast to change during pregnancy and lactation?
Guide to Physiology
There is no formal physiology exercise with this lab. However, APL Exercises 27-3 and 27-4 in the lab text are good reviews of meiosis, spermatogenesis,and oogenesis.