Fertilization

Question 1

where does fertilization occur

Answer 1

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

Question 2

where does the sperm enter the female reproductive system from first

Answer 2

cervix

Question 3

why do sperm become motile at ovulation

Answer 3

because of chemoattractants produced by cumulus cells surrounding the egg

Question 4

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

Answer 4

1. capacitation

2. the acrosome reaction to acquire this capability

Question 5

what is capacitation

Answer 5

period of conditioning in the female reproductive tract

Question 6

why is speeding to the ampulla not an advantage

Answer 6

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

Question 7

what happens during capacitation

Answer 7

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

Question 8

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

Answer 8

capacitated sperms

Question 9

what induces acrosome reaction

Answer 9

zona proteins, ZP3

Question 10

what are the 3 phases of fertilization

Answer 10

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

Question 11

what is the function of the zona

Answer 11

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

Question 12

what allows the sperm to penetrate the zona

Answer 12

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

Question 13

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

Answer 13

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

Question 14

why do the enzymes alter the properties of the zona pellucida

Answer 14

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

Question 15

what mediates the initial adhesion of sperm to the oocyte

Answer 15

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

Question 16

what happens after adhesion

Answer 16

the plasma membranes of the sperm and egg fuse

Question 17

how does the egg respond after the spermatozoa enter the oocyte

Answer 17

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

Question 18

how does the zona pellucida prevent sperm binding and penetration

Answer 18

altering its surfacen and composition preventing polyspermy

Question 19

what is another way of preventing polyspermy

Answer 19

oocyte membrane becomes impenetrable to other spermatozoa

Question 20

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 ___________

Answer 20

second meiotic division
cytoplasm
second polar body
definitive oocyte.

Question 21

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

Answer 21

in a vesicular nucleus known as the female pronucleus

Question 22

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

Answer 22

spermatozoon

Question 23

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

Answer 23

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

Question 24

what three events occur during Metabolic activation of the egg

Answer 24

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

Question 25

what are the main results of fertilization

Answer 25

* 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

Question 26

during mitotic division of the zygote, what forms?

Answer 26

blastomeres

Question 27

what happens 3 days after fertilization

Answer 27

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

Question 28

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

Answer 28

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

Question 29

how does the blastocystic cavity form during blastocyst formation

Answer 29

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

Question 30

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

Answer 30

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

Question 31

implantation begins after the _______________ as disappeared

Answer 31

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

Question 32

what do the embryoblast and the trophoblast do

Answer 32

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

Question 33

where does the blastocyst nourishment from

Answer 33

secretions of the uterine glands

Question 34

after 6 days where does the blastocyst attach

Answer 34

to the endometrial epithelium

Question 35

what mediates initial attachment of the blastocyst to the uterus

Answer 35

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

Question 36

what do Integrin receptors for laminin and fibronectin promote

Answer 36

attachment and migration respectively

Question 37

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

Answer 37

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

Question 38

when does the secretory phase begin

Answer 38

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

Question 39

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

Answer 39

they become coiled and the tissue becomes succulent

Question 40

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

Answer 40

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

Question 41

where does the blastocyst implant along the endometrium

Answer 41

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

Question 42

what parts of the endometrium shed during menstruation

Answer 42

compact and spongy layers

Question 43

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

Answer 43

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

Question 44

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

Answer 44

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

Question 45

what are causes of female infertility

Answer 45

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

Question 46

what is a) oligozoospermia b) azoospermia

Answer 46

a) ejaculate contains very few live sperm | b) no live sperm

Question 47

what can overcome oligozoospermia and azoospermia

Answer 47

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

Question 48

when is intracytoplasmic sperm injection not useful

Answer 48

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