Lecture 15

Question 1

Ovarian Cycle

Answer 1

1. Follicular phase
2. Ovulation
3. Luteal phase

Question 2

Follicular phase

Answer 2

Days 1-14

Batch of primary follicles develop in response to FSH •Stimulates growth and release of estradiol

By time antrums begin to develop (in secondary follicles) one follicle in particular is selected to become mature follicle•In response to estradiol, dominant follicle upregulates FSH and LH receptors

High estradiol levels cause anterior pituitary to secrete less FSH (causing all follicles except for dominant to undergo atresia) and more LH, leading to Ovulation

Question 3

Ovulation

Answer 3

Rupture of the mature follicle and ejection of secondary oocyte polar body.

Surge of LH causes completion of mitosis I

Question 4

Luteal phase

Answer 4

Luteal phase begins with hemorrhaging of ruptured follicle

Epithelial cells lining follicle fill in the lumen and form corpus luteum (CL)(endocrine)

Progesterone and estrogen released from (CL) prepare uterus for implantation of embryo

Inhibin released from the corpus luteum also inhibits gonadotropin release

If fertilization does not occur, corpus luteum degenerates and is filled in with connective tissue
•Structure known as corpus albicans

Question 5

List several things that the female reproductive system does that the male system does not.

Answer 5

Produces oocytes. Hoses and nourishes the developing embrio/fetus/baby

Question 6

Androgynous embryonic structures

Answer 6

• Genital tubercle becomes clitoral glans
• Urogenital folds turn into labia minora
• Labioscrotal folds turn into labia majora

Question 7

Female External Genitalia

Answer 7

Clitoris
Labia majora
Labia minora

Question 8

Internal Genitalia

Answer 8

Ovaries
Uterine tubes
Uterus
Vagina

Question 9

What are the functions of the ovaries?

Answer 9

• Female gonads•Main functions are production of secondary oocytes (gametes) and secretion of female sex hormones
• Paired, lumpy, shaped like almonds, and about twice the size of
• Like the testes, covered and protected by tunica albuginea
• Has cortex and medulla
• Oocytes produced in cortex
• Medulla is connective tissue and contains blood vessels and nerves

Question 10

What are the regions of the ovaries?

Answer 10

• Has cortex(Outer) and medulla(Middle)
• Oocytes produced in cortex
• Medulla is connective tissue and contains blood vessels and nerves for nourishment

Question 11

What important structures are contained within the suspensory ligaments of the female pelvic cavity?

Answer 11

Contain ovarian artery, vein, lymphatics, and nerves. Important for nourishment

Question 12

Define folliculogenesis:

Answer 12

•Development of the follicles surrounding the gametes

FSH triggers the follicular cells to produce more estrogen progesterone and inhibin.

LH triggers completion

Question 13

Female secondary sex characteristics and hormone responsible.

Answer 13

Estrogen: Sex organs, skeletal growth, increased pelvic width, fat deposition, breast development.

Question 14

Thelarche

Answer 14

First sign of female puberty

Question 15

Pubarche

Answer 15

• Appearance of pubic and axillary hair, along with apocrine gland activity
• Produced as a result of androgens from adrenal cortex and ovaries

Question 16

Menarche

Answer 16

• Usually around age 12
• Minimum of 17-22% body fat required for menstruation
• Amenorrhea below 17%
• Low levels of leptin in blood suppresses gonadotropin release

Question 17

Why do females finish puberty first?

Answer 17

Because they do not ovulate for the first year and male finish about when they start to ovulate.

Question 18

Oogenesis

Answer 18

• Egg production –ovum is mature gamete
• Cyclical and results in production of one egg per month
• Many aspects of female reproductive physiology and behavior have evolved as a result of this
• In fifth or sixth week of embryonic development, oogonia (female germ cells) migrate to gonadal ridges
• Oogonia undergo mitosis until fifth month of fetal development to produce 6 or 7 million oogonia
• Go into state of arrested development until shortly before birth
• By time of birth, all oogonia have differentiated into primary oocytes, and are arrested in meiosis I

Question 19

What event of oogenesis typically occurs between the birth of the female and the onset of puberty?

Answer 19

• By the time puberty is reached, most primary oocytes have degenerated
• Known as atresia
• 2 million remain at birth, and 200,000 remain by puberty

Question 20

Primordial follicle

Answer 20

Cluster together in “egg nests”

Stuck in arrested meiosis I

Single layer of follicular cells surround primary oocyte

Question 21

Early primary follicle

Answer 21

Primary follicles also contain a primary oocyte

•The single layer of cells are now cuboidal and are called granulosa cells

Question 22

Late primary follicle

Answer 22

Primary oocyte
multiple layers of granulosa cells
•Stratified cuboidal

Question 23

Secondary follicle

Answer 23

stratified cuboidal epithelium surrounding a primary oocyte
•Cells secrete glycoprotein layer around oocyte called zona pellucida
•Thecal cells form around follicle
•LH and insulin cause thecal cells to absorb cholesterol from blood
•Used to synthesize androgens
•Androgens move to granulosa cells, which convert it to estrogen

Question 24

Mature follicle

Answer 24

Also called: Tertiary, vesicular, antral, or Graafian

•Antrum is much larger and crescent shaped

• Cumulus oophorus is a collection of granulosa cells that surrounds oocyte
  * Forms bridge between follicle wall and oocyte
• Protective layer of cells closest to oocyte called corona radiata
  * Acts as blood-oocyte barrier
• Secondary oocyte produced just prior to ovulation
  * Completion of meiosis I in response to which hormone?