15.1 Female Reproductive System

Question 1

What are the 3 parts of the female external genitalia?

Answer 1

1. labia majora
2. labia minora
3. clitoris

Question 2

What is the labia majora?

Answer 2

2 longitudinal folds of skin, covered by pubic hair, composed of stratified squamous epithelium (skin). Contain an abundance of adipose tissue, sebaceous (oil) glands, apocrine sudoriferous (sweat) glands. Homologous to scrotum

Question 3

What is the labia minora?

Answer 3

2 smaller folds of skin, located medial to labia majora, composed of stratified squamous epithelium (skin)

Question 4

What is the clitoris?

Answer 4

small, cylindrical mass of erectile tissue and nerves located at anterior junction of labia minora

Question 5

What are the 4 parts of the female internal genitalia?

Answer 5

1. oviducts (uterine/fallopian tubes)
2. uterus
3. cervix
4. vagina

Question 6

What are the oviducts?

Answer 6

1. extends from uterus
2. composed of 3 layers: mucosa, muscarinic, and serosa
3. epithelium: ciliated simple columnar cells to help move fertilized ovum or secondary oocyte toward uterus
4. function: transport secondary oocytes and fertilized ova to uterus. Conception must occur in fallopian tubes, not uterus? by the time the developing stage of stickiness occurs…

Question 7

What is the uterus?

Answer 7

1. where embryonic and fetal development occurs, or source of menstrual flow
2. 3 layers: perimetrium, myometrium, endometrium
3. 2 supportive ligaments:
   - broad ligament (looks like a big wing)
   - ovarian ligament: in a multipar woman (women with multiple children such as 7 or more individual pregnancies) - this can allow the uterus to sag into the vagina and corrective surgery must be used

Question 8

What is the cervix?

Answer 8

inferior, narrow portion of uterus that opens into the vagina (or opens into the uterus/womb)

Question 9

What is the vagina?

Answer 9

1. (sheath), fibromuscular canal lined with mucous membrane (nonkeratinized stratified squamous epithelium) that extends from uterine cervix to exterior of body
2. mucosa of vagina contains large stores of glycogen which decompose to produce organic acids - retards microbial growth but also harmful to sperm

Question 10

What is the function of the ovaries?

Answer 10

1. produce secondary oocytes (primordial follicles –> primary follicles)
2. produce hormones: progesterone, estrogen, inhibin, relaxin

Question 11

What is the germinal epithelium?

Answer 11

layer of simple epithelium (low cuboidal or squamous) that covers the surface of the ovary

Question 12

What are ovarian follicles?

Answer 12

located in ovarian cortex, consist of oocytes. Surrounding cells = follicular cells (single layer) that become granulosa cells (many layers), nourish developing oocyte and secrete estrogen as follicle grows larger

Question 13

What are the cells surrounding the oocyte and what is their function?

Answer 13

1. follicular cells: 1 layer
2. granolosa cells: many layers
3. function: nourish developing oocyte, secrete estrogen as follicle gets bigger

Question 14

What is a primary follicle?

Answer 14

primary oocyte + surrounded by granulosa cells

Question 15

What is a secondary follicle?

Answer 15

primary oocyte + multilayers of granulosa cells, granulosa cells begin to secrete follicular fluid

Question 16

What is a late tertiary follicle?

Answer 16

fluid-filled blister on surface of ovary

Question 17

What is atretic?

Answer 17

atresia - once there is a dominant secondary follicle, the majority of germ cells degenerate and never become primary oocytes

Question 18

What is a mature graafian follicle?

Answer 18

secondary oocyte + large, fluid-filled follicle. Ready to rupture and expel its secondary oocyte at ovulation

Question 19

What is the corpus hemorrhagicum?

Answer 19

ruptured follicle, what remains of the mature graafian follicle after ovulation

Question 20

What is the corpus luteum?

Answer 20

1. (yellow body), develops from corpus hemorrhagicum with each new menstrual cycle, remains in ovary after ovulation
2. secretes hormone progesterone
3. if no pregnancy occurs, the corpus luteum will form a scar known as the corpus albicans

Question 21

What is the corpus albicans?

Answer 21

scar tissue formed from corpus luteum

Question 22

What is follicular fluid/liquor?

Answer 22

nutritive, hormone-rich fluid secreted by granulosa cells, fills the antrum of the mature graafian follicle

Question 23

What is the zona pellucida?

Answer 23

1. superficial, clear glycoprotein layer/membrane surrounding the plasma membrane of an oocyte (between primary oocyte and granulosa cells)
2. secreted by oocyte and follicular cells
3. surrounded by cumulus oophorus
4. binds spermatozoa, required to initiate the acrosome reaction (only allow one sperm access to the egg, blocks the rest - prevents polyspermy)
5. excess genetic material is kicked out during the meiotic process - if one polar body remains, the pregnancy will terminate
6. if there is too much access to genetic material caused by a lack of Calcium, there will be a miscarriage in the first trimester

Question 24

What is the cumulus oophorus?

Answer 24

• cluster of cells that surround the oocyte both in the ovarian follicle and after ovulation. The innermost layer of the cells is the corona radiata
• the stalk for egg, contributes to corona radiata
• must be penetrated by spermatozoa for fertilization to occur

Question 25

What is the corona radiata?

Answer 25

1. innermost layer of cumulus oophorus/granulosa cells, attached to zona pellucida 2. slowly sloughs off as the ovulated egg travels to the uterus 3. prevents polyspermy: for fertilization to occur, sperm cells rely on hyaluronidase (an enzyme in the acrosome of spermatozoa) to disperse the corona radiata from the zona pellucida of the secondary (ovulated) follicle

Question 26

During oogenesis, what happens during the fetal period?

Answer 26

1. germ cells --> differentiate into oogonium (2n, stem cell) --> (mitosis) --> 2. develop into primary oocyte (2n) in primordial follicle --> prophase I of meiosis during fetal development but do not complete the phase until after puberty - during this arrested stage of development, each primary oocyte is surrounded by a single layer of flat follicular cells, and the entire structure is a primordial follicle

Question 27

During oogenesis. what happens at puberty?

Answer 27

1. each month after puberty until menopause, gonadotropins (FSH & LH, secreted by anterior pituitary) further stimulate development of several primordial follicles (primary oocyte + single layer of follicular cells), although only 1 primordial follicle typically reaches maturity needed for ovulation 2. primordial follicles --> primary follicles (primary oocyte + surrounded by granulosa cells) - as primary follicle grows, it forms the zona pellucida 3. primary follicle --> secondary follicle - granulosa cells begin to secrete follicular fluid, which builds up within the secondary follicle - innermost layer of granulosa cells become firmly attached to zona pellucida (corona radiata) 4. secondary follicle --> mature graafian follicle - diploid primary oocyte completes meiosis I to produce 2 haploid cells of unequal size (with 23 chromosomes each) - smaller cell = first polar body, a packet of discarded nuclear material - larger cell = secondary oocyte, receives most of the cytoplasm, undergoes meiosis II but stops at metaphase (until puberty)

Question 28

What happens at ovulation?

Answer 28

5. at ovulation, mature graafian follicle ruptures and releases secondary oocyte, where it is expelled into the pelvic cavity with first polar body and corona radiata, and swept into the uterine tube 1. if no fertilization occurs: cells degenerate 2. if sperm is present, meiosis II continues --> secondary oocyte splits into 2 haploid cells of unequal size - larger cell = ovum (mature egg), unites with sperm to form diploid zygote - smaller cell = second polar body

Question 29

SUMMARIZE the steps of oogenesis from the oogonium to the ovum (7 steps)

Answer 29

1. oogonium --> 2. primary oocyte in PRIMORDIAL follicle --> 3. primary oocyte in PRIMARY follicle --> 4. primary oocyte in SECONDARY follicle --> meiosis I completed by one primary oocyte each month --> 5. 1st polar body + secondary oocyte in MATURE graafian follicle --> metaphase II 6. ovulated secondary oocyte bursts out of MATURE graafian follicle + sperm cell --> meiosis II completed if fertilization occurs --> 7. 2nd polar body + ovum

Question 30

What happens when fertilization does not occur?

Answer 30

1. levels of ovarian hormones decrease, which causes the endometrium to slough off

Question 31

What is the role of the hypothalamus?

Answer 31

secretes gonadotropin-releasing hormone (GnRH) --> stimulates release of FSH (follicle-stimulating hormone) & LH (luteinizing hormone, creates corpus luteum)

Question 32

What is follicle-stimulating hormone (FSH)?

Answer 32

1. initiates follicular growth (primordial --> primary --> secondary follicle) 2. initiates secretion of estrogens by the growing ovarian follicles

Question 33

What is luteinizing hormone (LH)?

Answer 33

1. stimulates further development of follicles and their full secretion of estrogens 2. midcycle, LH triggers ovulation and then promotes formation of the corpus luteum (hence the name luteinizing hormone), which produces and secretes hormones (estrogens, progesterone, relaxin, and inhibin). 3. if there is no fertilization, the corpus luteum becomes a corpus albicans (scar tissue)