Fertilization - Exam 3

1. sperm must transverse the cervix

2. be transported through the uterus to the oviduct

3. undergo capacitation

4. bind to the oocyte

5. undergo acrosome reaction

6. penetrate the zona pellucida and fuse with the oocyte plasma membrane

What are the six things that must happen to spermatozoa in the female tract?

once the sperm are in the uterus

When is capacitation initiated?

when the male pronucleus has formed

When has a successful fertilization taken place?

cow, sheep, rabbit, primates, dogs, and cats

Which species ejaculate into the vagina?

pigs

Which species ejaculate into the cervix?

horses and camelids

Which species ejaculate into the cervical lumen where much of it goes directly into the uterine body (due to forceful copulation)?

in burst

How would you describe the way a stallion ejaculates?

highly concentrated with sperm

What are the first few bursts of a stallion ejaculation composed of?

lower in concentration of sperm, mostly seminal plasma

also coagulant

What are the last few bursts of a stallion ejaculation composed of?

to minimize retrograde sperm lost

What is the purpose of the seminal plasma in the last few bursts of ejaculation of a stallion?

boars

Which species ejaculates in a large volume?

flows into the uterus

What happens to most of a boar’s ejaculate?

accessory fluids

What does the first fraction of a boar's ejaculate consist of?

high sperm

What does the second fraction of a boar’s ejaculate consist of?

coagulates and reduces retrograde loss

What does the last fraction of a boar’s ejaculate do?

estradiol; neutrophils

In the immune response of the female; ______ causes _______ to accumulate in the vagina and uterine mucosa?

attack foreign materials (microorganisms introduced during copulation and also sperm)

What do neutrophils do in the female tract?

6-12 hours after introduction of sperm

When is there a large migration of neutrophils from uterine mucosa into uterine lumen?

the female just came out of estrus (just ovulated)

Why is there high estradiol in the female when sperm is introduced (why is there estradiol there to cause neutrophils to accumulate)?

rapid transport phase and sustained transport phase

What are the two phases of sperm transport?

rapid transport phase

sperm reach oviduct a few minutes after copulation

these sperm are generally not fertile

sustained transport phase

sperm transported to oviducts in a “trickle-like_ effect from reservoirs (cervical folds) in the tract

delivers sperm in a more uniform, sustained manner

Muscularis

What contracts to assist with sperm transport?

estradiol

prostaglandins in semen alsso increases contraction

What stimulates the muscularis contractions?

true

T/F: seminal plasma assist with sperm transport and boar seminal plasma advances time of ovulation

sialomucin and sulfomucin

What are the two types of mucus that the bonvine cervix produces?

sialomucin

low viscosity mucus

produced by cells in basal areas or crypts (folds)

sulfomucin

high viscosity mucus

produced in apical portions of the epithelium covering the tips of the cervical folds

they get stuck and end up getting flushed out

What happen to sperm that get stuck in the viscous sulfomucin of the cervix?

going through the sialomucin in the folds of the cervix

What is considered the “privileged pathway” of sperm transport?

true

T/F: the “privileged pathway” of sperm transport is not a direct route and requires sperm to make an effort. However, it also makes it easier to remove poor swimming/dead sperm as well as bacteria from the tract

true

T/F: When sperm leave the male, they are not at maximum fertility

the female tract to trigger capacitation

What do sperm need in order to reach maximum fertility?

capacitation

biochemical changes occur in plasma membrane of the sperm, particularly the head

involves stripping of the various proteins that cover the sperm

they become hyperactive and motility changes

What happens as sperm moves into the oviduct?

they switch from swimming in a straight line to a frenzied, circular motion

What does it mean when the sperm undergo motility changes in the oviduct?

ampulla

Motility changes occur in the _______ (specific part of oviduct) and facilitate the sperm-oocyte interaction

zona binding proteins

What does sperm contain on the plasma membrane that becomes uncovered during capacitation?

primary zona binding site

acrosome reaction promoting ligand (2nd binding site)

What are the two bind sites used by sperm in fertilization?

binds first and is responsible for adherence

What is the purpose of the primary zona binding site?

causes a signal transduction which initiates acrosomal reaction

What is the purpose of the acrosome promoting ligand (2nd binding site)?

acrosomal reaction

an orderly fusion of spermtozoal plasma membrane and outer acrosomal membrane

1. reaction enables sperm to penetrate the zona pellucida

2. exposes equatorial segment so can later fuse with plasma membrane of oocyte

What are the two purposes of the acrosomal reaction?

multiple; vesicles (vesiculation)

The acrosomal reaction begins when plasma membrane of sperm forms ______ fusion sites with oouter acrosomal membrane of the sperm which forms _______.

dispered; inner acrosomal membrane

After vesiculation, acrosomal contents are ______ and sperm nucleus is left with the _____ _________ ________ surrounding it.

the acrosomal reaction will not happen correctly

What will happen if the acrosome is damaged?

heat, cold, pH

What can damage the acrosome?

enzymes; zona pellucida

The acrosomal reaction releases ______ that allow sperm to digest its way through the _____ _______.

acrosin and proacrosin

What are the two enzymes released during the acrosomal reaction?

acrosin

enzyme that hydrolyzes zona proteins and enhances sperm’s ability to bind

proacrosin

inactive version of acrosin

strong affinity for the zona

a few minutes

How long does the penetration of the zona pellucida by the sperm take?

flagellar action

What is the penetration of the zona pellucida by the sperm assisted by?

ZP; intact

During fertilization; enzymes produce a small hole in ___, most of the zona stays ______.

equatorial segment; fusion protein

After sperm penetrates the zona, the plasma membrane of oocyte fuses with the membrane of the _____ ____. This is assisted by a _____ ____.

cortical reaction and vitelline block

What are the two methods of regulation of entry?

cortical reaction

creates a zona block so that more sperm cannot penetrate

prevents polyspermy

vitelline block

reduction in oocyte plasma membrane’s ability to fuse with additional sperm, also prevents polyspermy

true

T/F: some species have both blocks (cortical block and vitelline block), some have one or the other

it decondenses and becomes the amle pronucleus

What happens to the sperm nucleus after fertilization?

syngamy

the female pronucleus and male pronucleus fuse allowing the chromosomes from each to pair up, creating a single-celled organism

retained five years

What is the fertile life-span of sperm in some reptiles?

9 to 11 days

What is the fertile life-span of sperm in a b*tch?

4 to 5 days

What is the fertile life-span of sperm in camelids?

1.5 to 2 days

What is the fertile life-span of sperm in cows?

4 to 5 days

What is the fertile life-span of sperm in mares?

5 to 6 days

What is the fertile life-span of sperm in a woman?

estrus; sperm

Canines have lengthy ____ and length life-span of ____, which allows for more than one sire in a litter

superfecundation

What is it called when there is more than one sire for a single litter?

true

T/F: in humans, the lengthy fertile period of sperm coupled with no defined period of sexual receptivity results in a fairly high likelihood of pregnancy.

33%; 2

On average, in humans, there is a ___ percent chance of pregnancy when copulation occurs within __ days of ovulation.