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+ CAPS 301: Respiratory, Renal, GI, Endocrinology, Reproduction > Female Reproduction > Flashcards

Female Reproduction Flashcards

1
Q

What do ovaries (female gonads) do?

A

produce gametes (ova) by oogenesis, and two sex steroid hormones – estrogen (estrodyl E2), and progesterone

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2
Q

What are the 3 parts of the reproductive tract?

A
  • oviducts (Fallopian tubes)
  • uterus
  • vagina
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3
Q

What do the oviducts (Fallopian tubes) do?

A

receive ovulated ova – site of fertilization

fimbriae at end of tubes catch fertilized egg

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4
Q

What is the uterus?

A

site of menstrual bleeding, and embryonic and fetal development

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5
Q

What does the vagina do?

A

connects uterus to external environment – site of sperm deposition

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6
Q

Production of Ova by Ovary

How is oogenesis in females different than spermatogenesis in males?

A
  • total supply of eggs is determined at birth (while sperm is produced only after reaching puberty)
  • eggs are released in monthly cycles from puberty until menopause (age ~51 in Canada)
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7
Q

Production of Ova by Ovary

When do oogonia?

A

appear during early prenatal development, divide by mitosis and are diploid

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8
Q

Production of Ova by Ovary

Before Birth

A
  • ~400,000 of oogonia enlarge in each ovary to form primary oocytes
  • these enter meiosis, but become arrested in early stages (prophase) of first meiotic division
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9
Q

Production of Ova by Ovary

At Birth

A

each primary oocyte is surrounded by single layer of cells to form primordial follicle (primary oocyte + follicular cell)

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10
Q

Production of Ova by Ovary

What is a primordial follicle composed of?

A

primary oocyte + follicular cell

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11
Q

Production of Ova by Ovary

What is an ovary reserve?

A

number of primordial follicles in ovaries at time of birth

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12
Q

Production of Ova by Ovary

Between Birth and Puberty

A
  • no new oocytes are produced

- primordial follicles either remain quiescent or undergo atresia

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13
Q

Production of Ova by Ovary

What is atresia?

A

degeneration due to apoptosis or programmed cell death

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14
Q

Production of Ova by Ovary

After puberty

A
  • pools of 40-50 primordial follicles are ‘recruited’ to enter monthly ovarian cycles
  • each cycle results in single ‘dominant’ follicle that releases its oocyte during ovulation
  • recruitment continues until ovarian pool of primordial follicles is exhausted at menopause
  • only ~400 follicles ovulate during reproductive life of woman
  • remaining 99.9% undergo atresia
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15
Q

Production of Ova by Ovary

What do recruited primordial follicles do?

A

form primary follicles surrounded by single layer of cube-shaped granulosa cells (GCs)

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16
Q

Production of Ova by Ovary

What do primary follicles become?

A

become secondary follicles as they begin to accumulate multiple layers of GCs, and acquire

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17
Q

Production of Ova by Ovary

What do secondary follicles develop into?

A

develop into tertiary (Graafian) follicles as a result of rapid growth and formation of fluid-filled antrum (fluid-filled space)

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18
Q

Production of Ova by Ovary

What happens to tertiary follicles during each ovarian cycle?

A

one of the tertiary follicles becomes dominant and ovulates, and remaining follicles undergo atresia

19
Q

Production of Ova by Ovary

What does the primary oocyte of dominant follicle do just before ovulation?

A
  • completes first meiotic division, and is no called secondary oocyte (large secondary oocyte and first polar body are formed)
  • secondary oocyte becomes arrested at one of the early phases of 2nd meiotic division
20
Q

Production of Ova by Ovary

What does the primary oocyte of dominant follicle do following ovulation?

A

released ovum enters oviduct and (if sperm are present) may be fertilized there

21
Q

Production of Ova by Ovary

How is haploid mature oocyte produced?

A

when 2nd meiotic division is completed, only after haploid sperm has crossed ovum’s cell membrane

22
Q

Production of Ova by Ovary

What is folliculogenesis?

A

follicle growth

23
Q

Production of Ova by Ovary

What are the 2 phases of folliculogenesis?

A
  • preantral or gonadotropin-independent phase

- antral or gonadotropin-dependent phase

24
Q

Production of Ova by Ovary

What occurs in the first stage (preantral or gonadotropin-independent phase) of folliculogenesis?

A

growth and differentiation of follicles (primordial follicles to secondary follicles)

25
Q

Production of Ova by Ovary

What controls the first stage (preantral or gonadotropin-independent phase) of folliculogenesis?

A

controlled by locally produced growth factors through autocrine/paracrine mechanisms

26
Q

Production of Ova by Ovary

What happens in the second stage (antral or gonadotropin-dependent phase) of folliculogenesis?

A

additional growth of few follicles, followed by selection of single dominant follicle which releases its oocyte as a result of ovulation

27
Q

Production of Ova by Ovary

What controls the second stage (antral or gonadotropin-dependent phase) of folliculogenesis?

A

controlled by FSH, LH, estrogen and growth factors

28
Q

Production of Ova by Ovary

After Ovulation

A

remnants of dominant follicle in wall of ovary transform into corpus luteum (CL)

29
Q

Ovarian Cycle

What are the 3 critically important events?

A
  • selection and development of dominant follicle
  • ovulation
  • formation of CL
30
Q

Ovarian Cycle

What is the average length of ovarian cycle?

A

28 days

31
Q

Ovarian Cycle

What are the two phases?

A

(days 1-14) follicular phase

(days 15-28) luteal phase

32
Q

Ovarian Cycle

What is the follicular phase (days 1-14) characterized by?

A

presence of maturing follicles – culminates in ovulation (days leading to ovulation)

33
Q

Ovarian Cycle

What is the luteal phase (days 15-28) characterized by?

A

presence of CL – culminates in menstruation, UNLESS ovulated egg has been fertilized

corpus luteum is formed

34
Q

Ovarian Cycle

What is the cycle controlled by?

A

complex hormonal interactions

35
Q

Ovarian Cycle

What does estrogen do?

A

estrogen (E) regulated changes in hypothalamic GnRH pulse frequency control release of FSH and LH from anterior pituitary

36
Q

Ovarian Cycle

Process

A
  1. early in follicular phase: low E levels produced by maturing follicles maintain low frequency of GnRH pulses (release) in hypothalamus:
    - this favours release of FSH over LH
    - at this stage: low E has negative feedback effect on GnRH secreting neurons
  2. at roughly day 10 of cycle: very high concentration of E produced by dominant follicle reaches threshold to induce very high GnRH pulse frequency (release) in hypothalamus
    - this now favours release of LH over FSH
    - at this stage: very high E has positive feedback effect on GnRH secreting neurons
  3. LH peak observed on about day 13 of cycle triggers the following events:
    - completion of meiosis I by oocyte (inducing transition of primary oocyte → secondary oocyte)
    - rupture of follicular wall
    - ovulation
    - formation of CL
  4. CL begins to secrete high levels of progesterone (P) and moderate amounts of estrogen (E)
    - high concentration of both ovarian steroids inhibits GnRH release from hypothalamus, resulting in inhibition of LH and FSH release from anterior pituitary
    - high E and P have strong negative feedback effect on GnRH secreting neurons
  5. P and E levels remain high for about a week – then, unless pregnancy occurs, CL begins to deteriorate and stops producing P and E
  6. new cycle begins (back to step 1)
37
Q

Ovarian Cycle

What do hormonal changes associated with the cycle have significant effects on?

A

uterus

38
Q

Ovarian Cycle

What does the uterine (menstrual) cycle consist of?

A

repeating changes in structure of uterine lining or endometrium

39
Q

Ovarian Cycle

What are the 3 phases of the uterine (menstrual) cycle?

A
  • proliferative
  • secretory
  • menstrual
40
Q

What is the proliferative phase of the uterine (menstrual cycle) caused by?

A

stimulated and sustained by increasing levels of E produced by rapidly developing follicles and involves development of endometrial glands and vascularization of lining

  • as a result, by the time of ovulation, the so-called ‘functional zone’ of endometrium is several mm thick, glands secrete mucus rich in glycogen, and numerous spiral arteries are present
41
Q

What is the secretory phase of the uterine (menstrual cycle) caused by?

A

begins at ovulation, as endometrial glands enlarge and produce large amounts of secretions under combined stimulatory effects of P and E from CL

  • secretory activities peak at about day 12 after ovulation and then decline as CL begins to degenerate
  • as a result of rapidly decreasing P and E levels, spiral arteries constrict, reducing blood flow to endometrium and causing rapid degeneration of its functional zone
42
Q

What is the menstrual phase of the uterine (menstrual cycle) caused by?

A

weakened arterial walls rupture, blood and degenerating lining enter uterine lumen and are discharged from vagina

  • sloughing off of endometrial tissue continues for several days until rising E levels produced by next batch of developing follicles stimulate repair and regeneration of lining
43
Q

Ovarian Cycle

What are endocrine activities in ovary regulated by?

A

hypothalamic-pituitary-ovarian axis

+ CAPS 301: Respiratory, Renal, GI, Endocrinology, Reproduction (32 decks)

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