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Med 105 > Fertilization > Flashcards

Fertilization Flashcards

1
Q

where does fertilization occur

A

ampullary region of the uterine tube (widest part and closest to the ovary)

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2
Q

where does the sperm enter the female reproductive system from first

A

cervix

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3
Q

why do sperm become motile at ovulation

A

because of chemoattractants produced by cumulus cells surrounding the egg

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4
Q

Spermatozoa are not able to fertilize the oocyte
immediately upon arrival in the female genital tract but
must undergo
1. ____________
2. ____________

A
  1. capacitation

2. the acrosome reaction to acquire this capability

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5
Q

what is capacitation

A

period of conditioning in the female reproductive tract

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6
Q

why is speeding to the ampulla not an advantage

A

capacitation has not yet occurred so such sperm are not capable of fertilizing the egg

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7
Q

what happens during capacitation

A

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

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8
Q

only ______________ can pass through the corona cells and undergo the acrosome reaction

A

capacitated sperms

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9
Q

what induces acrosome reaction

A

zona proteins, ZP3

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10
Q

what are the 3 phases of fertilization

A

Phase 1, penetration of the corona radiata
Phase 2, penetration of the zona pellucida
Phase 3, fusion of the oocyte and sperm cell membranes

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11
Q

what is the function of the zona

A

a glycoprotein shell surrounding the egg that facilitates and maintains sperm binding and induces the acrosome reaction

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12
Q

what allows the sperm to penetrate the zona

A

Release of acrosomal enzymes (acrosin) allows sperm to penetrate the zona

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13
Q

what does the sperm coming into contact with the plasma membrane lead to

A

release of lysosomal enzymes from cortical granules lining the plasma membrane of the oocyte

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14
Q

why do the enzymes alter the properties of the zona pellucida

A

to prevent sperm penetration and inactivate species-specific receptor sites for spermatozoa on the zona surface

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15
Q

what mediates the initial adhesion of sperm to the oocyte

A

interaction of integrins on the oocyte and their ligands, disintegrins, on sperm

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16
Q

what happens after adhesion

A

the plasma membranes of the sperm and egg fuse

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17
Q

how does the egg respond after the spermatozoa enter the oocyte

A
  1. Cortical and zona reaction
  2. Resumption of the second meiotic division
  3. Metabolic activation of the egg
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18
Q

how does the zona pellucida prevent sperm binding and penetration

A

altering its surfacen and composition preventing polyspermy

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19
Q

what is another way of preventing polyspermy

A

oocyte membrane becomes impenetrable to other spermatozoa

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20
Q

The oocyte finishes its _________ immediately after entry of the spermatozoon. One of the daughter cells, which receives hardly any _____, is known as the __________, the other daughter cell is the ___________

A

second meiotic division
cytoplasm
second polar body
definitive oocyte.

21
Q

where do chromosomes (22+X) arrange themselves during Resumption of the second meiotic division

A

in a vesicular nucleus known as the female pronucleus

22
Q

what probably carries the activation factor during Metabolic activation of the egg

A

spermatozoon

23
Q

Within the cytoplasm of the oocyte, the nucleus of the sperm __________________. The tail of the sperm _________________. During growth, the male and female pronuclei _______________

A

Within the cytoplasm of the oocyte, the nucleus of the sperm enlarges to form the male pronucleus. The tail of the sperm degenerates. During growth, the male and female pronuclei replicate their DNA

24
Q

what three events occur during Metabolic activation of the egg

A
  1. Condensation of the chromosomes,
  2. Arrangement of the chromosomes for mitotic cell division
  3. First cleavage division of the zygote occur
25
Q

what are the main results of fertilization

A
  • Restoration of the diploid number of chromosomes
  • Determination of the sex of the new individual
  • Initiation of cleavage
  • Without fertilization, the oocyte usually degenerates 24 hours after ovulation
26
Q

during mitotic division of the zygote, what forms?

A

blastomeres

27
Q

what happens 3 days after fertilization

A

embryo divides again to form a 16-cell morula (mulberry)

28
Q

what do the inner cell mass and the outer cell mass of the morula form

A

The inner cell mass gives rise to tissues of the embryo proper, and the outer cell mass forms the trophoblast, which later contributes to the placenta

29
Q

how does the blastocystic cavity form during blastocyst formation

A

Shortly after the morula enters the uterus uterine fluid

passes through the zona pellucida to form a fluid -filled space —the blastocystic cavity— inside the morula

30
Q

as the fluid increases in the blastocystic cavity, what does the blastomere separate into

A

The trophoblast, the thin outer cells that give rise to the embryonic part of the placenta
The embryoblast, a discrete group of blastomeres that is the primordium of the embryo

31
Q

implantation begins after the _______________ as disappeared

A

zona pellucida. its shedding allows the blastocyst to increase rapidly in size

32
Q

what do the embryoblast and the trophoblast do

A

the embryoblast projects into the blastocystic cavity and the trophoblast forms the wall of the blastocyst

33
Q

where does the blastocyst nourishment from

A

secretions of the uterine glands

34
Q

after 6 days where does the blastocyst attach

A

to the endometrial epithelium

35
Q

what mediates initial attachment of the blastocyst to the uterus

A

L-selectin on trophoblast cells and its carbohydrate receptors on the uterine epithelium

36
Q

what do Integrin receptors for laminin and fibronectin promote

A

attachment and migration respectively

37
Q

what layers does the trophoblast proliferate and differentiate into after the blastocyst binds to the epithelium

A

The cytotrophoblast, the inner layer of trophoblast cells
The syncytiotrophoblast the outer layer consisting of
a multinucleate protoplasmic mass formed by the fusion of cells of trophoblast

38
Q

when does the secretory phase begin

A

approximately 2 to 3 days after ovulation in response to progesterone produced by the corpus luteum

39
Q

what happens to the uterine glands and arteries during the secretory phase

A

they become coiled and the tissue becomes succulent

40
Q

what are the three distinct layers can be recognized in the endometrium due to the coiling of the uterine glands and arteries

A

a superficial compact layer, an intermediate spongy layer, and a thin basal layer

41
Q

where does the blastocyst implant along the endometrium

A

anterior or posterior wall of the body of the uterus where it becomes embedded between the openings of the glands

42
Q

what parts of the endometrium shed during menstruation

A

compact and spongy layers

43
Q

what happens to the venules and sinusoidal spaces when fertilization doesn’t occur

A

gradually become packed with blood cells, and an extensive diapedesis of blood into the tissue is seen

44
Q

what is the functions of the basal arteries (arteries in the basal layer of the endometrium)

A

functions as the regenerative layer in the rebuilding of glands and arteries in the proliferative phase

45
Q

what are causes of female infertility

A

occluded uterine tubes (most commonly caused by pelvic inflammatory disease), hostile cervical mucus, immunity to spermatozoa, absence of ovulation

46
Q

what is

a) oligozoospermia
b) azoospermia

A

a) ejaculate contains very few live sperm

b) no live sperm

47
Q

what can overcome oligozoospermia and azoospermia

A

intracytoplasmic sperm injection (a single sperm is injected into the cytoplasm of the egg to cause fertilization)

48
Q

when is intracytoplasmic sperm injection not useful

A

infertility resulting from blocked uterine tubes or oligospermia (reduced number of sperms)

Med 105 (16 decks)

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