Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Reproductive Anatomy > Oogenesis and Menstruation > Flashcards

Oogenesis and Menstruation Flashcards

1
Q

What are primordial germ cells?

A

Earliest undifferentiated sex cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Describe the embryology of the primordial germ cell?

A
  1. Originate in epiblast
  2. 3rd week - migrate to yolk sack close to allantois
  3. 4th week - travel along dorsal mesentery of hindgut
  4. 5th week - Arrive at primitive gonads
  5. 6th week - invade genital ridges
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is oogenesis?

A

Primordial germ cells in ovaries differentiate into Oogonia

- Begins shortly after arrival in ovary

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Describe oogenesis?

A
  1. Begins in the embryo when primordial germ cells undergo mitotic divisions to produce diploid oogonia.
  2. Each oogonium will develop into primary oocyte by the time of birth of the female, resulting in all potential ova being present in the ovaries at birth (production of oogonia stops and never resumes)
  3. Between birth and puberty, primary oocytes enlarge and their surrounding follicles grow: They replicate their DNA and enter Prophase and remain there until activated by hormones (Puberty)
  4. After puberty during each ovarian cycle, FSH stimulates a follicle to enlarge and the primary oocyte completes meiosis I
  5. LH triggers ovulation and the secondary oocyte is released from the follicle and is arrested in metaphase I until fertilization
  6. If the sperm cell penetrates the secondary oocytes membrane, meiosis II will occur
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

How many oogonia are present by 5 months of gestation?

A

6 – 7 million

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

How many primary oocytes are present at birth?

A

About 700 000 – 2 million primary Oocytes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

How many primary oocytes are present at puberty?

A

400,000

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

How many primary oocytes are ovulated?

A

<500

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

How many primary oocytes are fertilized?

A

<15

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is an ovarian follicle?

A

primary oocytes surrounded by epithelial cells (follicular cells)
- right before birth

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Describe ovarian follicles?

A
  • Follicle occur in superficial ovarian cortex

- Basal lamina surrounds follicular cells separating follicle & vascularized stroma

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What are primordial follicles?

A

follicles formed during fetal life

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What stimulates the follicular growth of primordial follicles?

A

FSH

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Follicular growth of primordial follicles involves?

A
  1. Oocyte growth
  2. Follicular cells proliferation
  3. Differentiation of stromal fibroblasts around follicle
  4. Selection of dominant follicle
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What are the 2 sexual cycles in females?

A
  1. ovarian cycle

2. uterine (menstrual) cycle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Name the phases of the Ovarian cycle?

A
  1. folicular phase

2. luteal phase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Name the phases of the menstrual cycle?

A
  1. Menstrual phase
  2. Proliferative phase
  3. Secretory phase
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What is the ovarian cycle?

A

Monthly series of events associated with maturation of egg
1. Follicular Phase - Follicular growth (day 1 - 14)
2. Luteal phase - Corpus luteum activity
(days 14 - 28)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Describe the primordial follicle?

A

Has single layer of flattened follicle cells

– fetal period

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Describe the formation of unilaminar primary follicle?

A

Follicular cells undergo mitosis and form a simple cuboidal epithelium around growing oocyte

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Describe the formation of multilaminar primary follicles?

A
  • Follicular cells continue to proliferate forming a stratified follicular epithelium called GRANULOSA
  • Oocyte produces zona pellucida between oocyte and first layer of granulosa cells (surrounds the oocyte)
  • follicular theca forms from differentiation of stromal cells (immediate cells outside each growing primary follicle)
22
Q

What is the zona pellucida?

A

a thick matrix composed of 4 glycoproteins
(ZP1 - ZP4)
- ZP3 & ZP4 serves as receptors for sperm

23
Q

Describe the differentiation of follicular theca?

A

further differentiates into

  1. theca interna - well vascularized endocrine tissue
  2. theca externa - fibroblasts & smooth muscle
24
Q

Describe the formation of the secondary follicle?

A

Move deeper in cortex, follicular fluid accumulates between cells
- an antrum forms (all cavities unite to form a large one)

25
Q

What is the other name for secondary follicle?

A

Antral or Vesicular Follicle

26
Q

Describe the formation of a mature (Graafian after 90 days) follicle?

A

Cumulus oophorus (small hill-like or elevated thickening structure formed by granulosa cells) protrudes into growing antrum
- corona radiate forms from granulosa cells immediately surrounding zona pellucida
Note: Corona radiate accompanies oocyte as it is ovulated

27
Q

When does ovulation occur?

A

midway through the menstrual cycle, around day 14

28
Q

Describe what happens just before ovulation to oocytes?

A
  1. Oocyte complete meiosis I
    • One Daughter cell retains almost all the
      cytoplasm & becomes Secondary Oocyte.
    • The other becomes the first polar body
      (a small nonviable cell)
  2. Oocyte begin Meiosis II but arrests at
    Metaphase II
29
Q

What is the luteal phase?

A

Post-ovulation, ruptured follicle becomes corpus luteum

30
Q

Corpus luteum secretes what hormones?

A

progesterone and estrogen

31
Q

What happens to the corpus luteum if pregnancy fails?

A

corpus luteum degenerates & the remnant is corpus albicans (scar)

32
Q

What happens to the corpus luteum if pregnancy succeds?

A

corpus luteum persists until placenta is ready to take hormonal duties

33
Q

Name the hormones that regulate the ovarian cycle?

A
  1. Gonadotropin-releasing hormone (GnRH)
  2. Pituitary gonadotropins (FSH, LH)
  3. ovarian Estrogen & Progesterone
34
Q

Follicular development depends on which hormones?

A

FSH from pituitary grand whose secretion is stimulated by GnRH

35
Q

Granulosa cells produce?

A

Inhibin

- hormone responsible for negative feedback of Estrogen & Progesterone

36
Q

Which hormone assists in the development of vesicular follicles?

A

estrogen

37
Q

What is the uterine cycle?

A

Series of cyclic monthly endometrium changes
- Responds to changes in ovarian hormonal
levels in blood

38
Q

Describe the proliferative (Estrogenic or Follicular) phase?

A
  1. Endometrium rebuilds itself
  2. Under influence of rising estrogen levels; endometrium generates new functional layer
  3. Endometrium becomes thick & well
    vascularized
    - Ovulation occurs at end of this stage (day 14) in response to LH surge
39
Q

Function of estrogen in the proliferative phase?

A
  1. induces synthesis of progesterone receptors in endometrial cells
  2. cause thick & sticky cervical mucus to become thin to facilitate sperm passage
40
Q

When does the proliferative phase take place?

A

days 6 - 14

41
Q

Describe the secretory (progestational) phase?

A
  • Endometrium prepares for implantation of embryo
  • Rising levels of progesterone converts functional layer of endometrium to a secretory mucosa and inhibits LH release by anterior pituitary
  • Uterine glands secrete nutritious glycoproteins into the uterine cavity to sustain embryo until it has implanted
42
Q

What happens in the secretory phase if fertilization has not occured?

A
  • corpus luteum begins to degenerate toward the end of secretory phase as LH levels decline
  • Progesterone levels fall, depriving
    endometrium hormonal support, hence,
    menstruation begins on day 28
43
Q

What happens in the secretory phase if fertilization takes place?

A

human chorionic gonadotropin from embryo prevents corpus luteum degeneration until 4th month when placenta takes over progesterone production

44
Q

When does the menstrual cycle start again?

A

the first day of menstrual flow

45
Q

What does does the secretory phase occur?

A

days 15 - 28

46
Q

Describe the menstrual phase?

A
  • Uterus sheds its functional endometrium layer
  • Ovarian hormone levels decreases,
    endometrium enters ischemic phase.
  • Functional layer of endometrium detaches
    from uterine wall accompanied by bleeding
    for 3-5 days
  • Detatched tissue & blood pass out as
    menstrual flow which marks beginning of
    new cycle
47
Q

What is amenorrhea?

A

absence of menstrual periods

48
Q

What is dysmenorrhea?

A

Painful menstrual periods due to uterine contractions

49
Q

What is menorrhagia?

A

heavy or prolonged periods

50
Q

What is infertility?

A

not getting pregnant despite having carefully timed unprotected sex for one year

51
Q

What are assisted reproduction techniques?

A

hormones like FSH administered to induce multi-follicular growth in females or inducing sertoli cells function in males

Reproductive Anatomy (16 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions