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anatomy FB1 > L3: Ovulation, Fertilization & Implantation > Flashcards

L3: Ovulation, Fertilization & Implantation Flashcards

1
Q

What controlled human Sexual cycles?

A

Hypothalamus which produce GnRH

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2
Q

How does the hypothalamus controls the Sexual cycles?

A

Because it acts on cells of the anterior pitiutary gland > which secrete gonadotropins (LH&FSH) > puberty

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3
Q

The ovarian cycle: (the phases are)

A
  • Follicular phase
  • ovulation
  • luteal phase
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4
Q

What is the role LH & FSH in female ovarian cycles?

A

• stimulate and control cyclic changes in the ovary

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5
Q

What stimulates the primary-stage (preantral ) follicles? (Follicular phase)

A

the influence of FSH

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6
Q

How many primary-stage (preantral ) follicles are stimulated?

A

15 to 20

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7
Q

What is the result at the end of the follicular phase?

A

Only one of these follicles will reach full maturity the others degenerate and become atretic and replaced by connective tissue forming corpus atreticum.

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8
Q

How is the proliferation of the granulosa mediated?

A

by growth differentiation factor 9 > GDF9

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9
Q

define growth differentiation factor 9 (GDF9)

A
  • a member of the transforming growth factor beta

* important to change the secondary follicle to a pre-antral follicle

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10
Q

GDF9 require what for the conversion

A

This requires FSH, activins, inhibin, androgens, estrogen, GDF9, BMP15

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11
Q

What is the function of Cumulus cells

A

continuously supplying the cell with hormones + secreting chemoattractant for the sperm

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12
Q

What is the importance of the granulosa cells?

A

Nourish the oocyte with hormones mainly estrogen.

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13
Q

What is the role of AMH? (anti-Mullerian hormone)

A

Inhibition follicles allowing only one to mature > regulation of ovarian follicle growth.

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14
Q

How does Theca interna and granulosa cells produce estrogens?

A

theca interna cells produce > androstenedione and testosterone > and granular cells convert these hormones to > estrone and 17-beta estradiol.

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15
Q

what happens after estrone & 17-beta estradiol production?

A

Uterine endometrium enters the proliferative phase

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16
Q

what happens to the uterus in the proliferative phase?

A

There is significant thickening of the wall of the uterus as a preparation for implantation

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17
Q

Why does the cervical mucus get thinner?

A

To allow passage of sperm

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18
Q

The ovarian cycle:

A
  1. Follicular phase > Follicular growth > GDF9
  2. ovulation > LH surge lead to ovulation > release the oocyte by rupture of follicle
  3. luteal phase > corpus luteum
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19
Q

Primary oocyte to begin to mature within the……

A

growing follicles

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20
Q

Corpus luteum develop from….

A

the remaining of the follicle

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21
Q

The corpus luteum degenerates if

A

a secondary oocyte is not fertilized

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22
Q

what happens to the remaining follicle after fertilization?

A

become corpus luteum

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23
Q

what is the role of corpus luteum?

A

it produces progesterone which is important for the endometrium

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24
Q

what prevents corpus luteum from degenerating?

A

HCG does not allow it to

degenerate coming from the embryo till the 3 or 4th month till the formation of the placenta

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25
Q

what happens to the corpus luteum if not fertilized?

A

the corpus luteum die

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26
Q

Why does FSH and LH surge during ovulation?

A

because we need the supply to change the secondary oocyte into a to a mature follicle. (complete meiosis 1)

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27
Q

who block additional oocyte for differentiation?

A

AMH

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28
Q

Why do we get the surge of estrogen around the same time of ovulation?

A

We get the estrogen from the theca interna and granulosa cells

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29
Q

what is LH surge role in the production of progesterone?

A

It stimulates production of progesterone by follicular stromal cells (leutinization) and
causes follicular rupture and ovulation

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30
Q

Why do we get a surge of progesterone after estrogen (after ovulation)?

A

Because it’s increases within the luteal phase in which the corpus luteum is the one
responsible for the surge

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31
Q

What is the importance of progesterone?

A

Important for thickening of the wall of the uterus

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32
Q

How does the oocytes to complete meiosis I and initiate meisosis II?

A

By the LH surge that elevates concentrations of maturation-promoting factor

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33
Q

What happens when LH has high concentrations? (surge)

A
  • increase collagenase activity
  • increase Prostaglandins
  • squeeze the oocyte along with its granulosa cells from the region of cumulus oophuru
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34
Q

what happens when we increase collagenase activity?

A

that will lead to the breakdown of collagen fibers surrounding the follicle.

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35
Q

what happens when we increase prostaglandins?

A

will cause muscular contractions in the ovarian wall

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36
Q

What happens to the granulosa cells in the wall of the ruptured follicle’s and the theca interna cells?

A

After ovulation they are vascularized by surrounding vessels

37
Q

How does the follicular rupture turn into corpus luteum?

A

Under the influence of LH these cells develop a yellowish pigment and transform into
lutein cells which secrete estrogens and progesterone

38
Q

What is the importance of estrogen and progesterone secretion?

A

cause uterine mucose to enter progestational phase in preparation for implantation

(Uterine wall thickening)

39
Q

How is the oocyte is carried into the uterine tube?

A

by sweeping motions of the fimbrae and by the cilia on the epithelial lining

40
Q

what is the role peristaltic muscular contractions in the Oocyte transport?

A

Once the oocyte in the tube peristaltic muscular contractions with the rate of trasport
regulated by the endocrine status during and after ovulation

41
Q

What happens to Cumulus cells after Oocyte is transported?

A

Cumulus cells withdraw their cytoplasmic processes from the zona pellucida and lose
contact with the oocyte.

42
Q

When doesThe fertilized oocyte reaches the of site fertilization?

A

in approximately 3 to 4 days

43
Q

What is the site of fertilization?

A

The uterine lumen > the ampulla

44
Q

What happens if fertilization doesn’t occur ?

A

shrinks to form a mass of fibrotic scar tissue, corpus albicans.

45
Q

when does the corpus luteum reaches maximum development if not fertilized

A

approximately 9 days post-ovulation

46
Q

What do you mean by corpus albicans?

A

A mass of fibrotic scar tissue formed from the degrading of the corpus luteum.

47
Q

What happens to progesterone levels when the corpus luteum degrade?

A

Progesterone production decreases and menstrual bleeding begins

48
Q

What happens if fertilization occur ?

A

occurs degeneration of corpus luteum is prevented by human chorionic gonadotropin (hCG) hormone

49
Q

who secretes HCG

A

the syncytiotrophoblast (which become the placenta)

50
Q

What is fertilization?

A

the process by which male and female gametes fuse and usually occurs in the ampullary region of the uterine tube

51
Q

What is the percentage of sperm that is deposited ithe vagina enter the cervix ?

A

• Only 1% of sperm

52
Q

And for how long does it (the sperm) survive?

A

survive for many hours

53
Q

How does sperm Move from the cervix to the uterine tube?

A

by muscular contractions of the uterus and uterine tube

54
Q

How long does it take?

A

from thirty minutes to 3 days

55
Q

what happen to the Sperm when they reach isthmus?

A

less motile and cease.

56
Q

What is Capacitation?

A

Glycoprotein coat and seminal plasma proteins are removed from the plasms membrane
that overlies the acrosomal region of the spermatozoa

57
Q

What is the sperm Conditioning period in the female reproductive tract?

A

lasts around 7 hours

58
Q

What initiates Capacitation?

A

Entails epithelial interactions between sperm and mucosal surface of the tube.

59
Q

Why is Capacitation important?

A

Because only capactiated sperm can pass through the corona cells (the outsider layer of the zona pellucida) and undergo the acrosome reaction.

60
Q

When does the acrosomal reaction Occur?

A

Occurs after binding to the zona pellucida this is induced by zona proteins

61
Q

What does the acrosomal reaction start with?

A

Start with the release of enzymes required to penetrate the zona pellucida, including acrosin- and trypsin-like substance

62
Q

What are the three stages of fertilization?

A
  1. Penetration of the corona radiata
  2. Penetration of the zona pellucida
  3. Fusion of the oocyte and sperm cell membrane
63
Q

how many spermatozoa reaches the site of fertilization?

A

300 to 500 out of 300 million spermatozoa reach the site of fertilization

64
Q

what is the zona pellucida?

A

a glycoprotein shell surrounding the egg

65
Q

what’s the function of zona pellucida?

A

facilitates sperm

binding and induces the acrosome reaction

66
Q

the role of the ligand ZP3:

A

mediated the binding and the acrosome reaction

67
Q

what does the release of acrosin do?

A

allows the sperm to penetrate the zona, coming in contact

with the plasms membrane of the oocyte

68
Q

when does the Fusion of the oocyte and sperm cell membrane

A

occurs after adhesion in the equatorial segment of the sperm with the oocyte

69
Q

What changes take place in the oocyte on entering spermatozoa? (From oocyte point of view)

A
  1. cortical and zona reactions > prevent the entry of other sperms
  2. Resumption of second meiotic division
  3. Metabolic activation of the egg > Fusion and doubling of DNA by mitosis
70
Q

What are the Results of the fusion of oocyte & sperm?

A
  1. Restoration of diploid number of chromosomes
  2. Sex determination
  3. Initiation of cleavage
71
Q

What’s a cleavage?

A

a series of mitotic divisions, increasing the number of cells

72
Q

How long does it take for the zygote to reach the two cell stage?

A

30 hours post-fusion.

73
Q

When does the zygote start cleavage process ?

A

Once the zygote has reached the two-cell stage

74
Q

When do we have blastomeres?

A

When the two-cell stage zygote become smaller with every dvision.

75
Q

What’s a morula?

A

Once the zygote reaches the 8-cell stage they become compact and resemble a mulberry

76
Q

inner cells of the morula makes up….

A

the inner cell mass

77
Q

the surrounding cells of the morula makes up….

A

the outer cell mass

78
Q

when is the blastocyst made?

A

Four days after fertilization the morula moves into the uterus and fluid filled cavity is formed

79
Q

Where does the Fluid begins to penetrate?

A

through the zona pellucida into the intercellular spaces of the inner cell mass.

80
Q

What do we call the cells after the Fluid begins to penetrate through the zona pellucida into the
intercellular spaces of the inner cell mass?

A
  • Cells of the inner cell mass > embryoblast that are at one pole
  • Cells of the outer cell mass > the trophoblast flatten
81
Q

What is formed by the trophoblast flatten?

A

form the epithelial wall of the blastocyst.

82
Q

The Uterus undergo several changes during the menstrual cycle in three stages, what are they?

A
  1. Follicular phase
  2. Secretory phase
  3. Menstrual phase
83
Q

when does the secretory phase happen?

A

which Starts 2-3 days after ovulation in response to progesterone

84
Q

When does the Implantation take place?

A

in the secretory phase

85
Q

What are the sides of Implantation?

A

ideally occurs within the body of the uterus, usually either on the anterior or posterior wall.

86
Q

Define ectopic pregnancy?

A

when the blastocyst may implant in an area other than the corpus uteri.

87
Q

Why is an ectopic pregnancy considered as obstetric emergencies that regrettably require
termination?

A

they threaten the life of the mother and the implantation site cannot facilitate the projected fetal growth.

88
Q

What are the most common ectopic pregnancies?

A

Tubal ectopic pregnancies which occur Within the fallopian tubes.

89
Q

What are the most common sites of Tubal ectopic pregnancy ?

A

is most likely to happen in the

ampulla > then at isthmus > followed by the infundibulum

anatomy FB1 (9 decks)

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