Sperm & Oocyte Transport, Fertilization, Embryonic Development

what is the process of preparing the male for ejaculation by improving the quality of the ejaculate

sexual preparation (teasing)

how are the nerves in the PVN stimulated?

by sensory stimulation (optic, olfactory, tactile, auditory)

what triggers the release of oxytocin from the posterior pituitary?

the stimulation of the nerves in the PVN

what does the release of oxytocin from the posterior pituitary trigger?

smooth muscle contractions in the distal tail of the epididymis and ductus deferens

what is intromission?

insertion into the female reproductive tract

what causes sensory stimulation of glans penis?

temperature and pressure from intromission

what muscle surrounds the pelvic urethra

urethralis muscle

what is the function of the urethralis muscle?

helps to move urine and semen during ejaculation

what muscle covers the bulb of the penis

bulbospongiosus muscle

function of the bulbosponsiosus muscle

aids in erection

function of the ischiocavernosus muscle

helps to maintain erection by increasing pressure

T/F you don’t have to tease to cause ejaculation

true

what is unique about boar copulation stats?

largest ejaculate volume and deposits sperm into the cervix of the female

what is retrograde loss

refers to the backward flow of sperm into the urinary bladder during ejaculation, instead of out through the urethra and penis

3 ways of immediate sperm transport

retrograde loss

phagocytosis

entrance into cervix/uterus

is a female’s immune system stimulated against deposited sperm?

yes

What is the first anatomical barrier in sperm transport

external cervical os

What is the second anatomical barrier in sperm transport

utero-tubal junction

what does estrus cause a high level of? what does this stimulate?

estradiol

mucus production

2 types of mucus

sulfomucin

sialomucin

characteristics of sulfomucin

high viscosity (thick)

characteristics of sialomucin

low viscosity (thin)

Where is the sulfomucin?

peaks of the cervical folds

Where is the sialomucin?

valleys of the cervical folds

What is the term for those traveling through the sialomucin? Why?

privileged pathway

lower viscosity (easier route to take to get through cervix)

what is the utero-tubal junction?

connection of the oviduct to the uterus

Where are sperm stored in the female tract?

sperm reservoirs of the isthmus

What do the sperm become after release from the sperm reservoirs?

capacitated

Describe a capacitated sperm

No coating over the receptors

hyperactive

bobbing motion

what is the function of seminal plasma fluid?

coat sperm membrane with proteins

cover sperm membrane molecules

ultimately renders sperm membrane inactive

what does it mean when sperm are decapacitated?

don’t have the capability to fertilize

what helps to wash off the seminal plasma coating?

uterine and oviducal fluid

what does capacitation increase?

O2 uptake by sperm

flagellar activity (hyperactive)

bobbing motility

why do capacitated sperm bob?

to increase the area they cover to have a better chance of finding and fertilizing the egg

what hormone helps to keep the gametes in the oviduct?

estradiol

what hormone helps to open the oviduct?

progesterone from diestrus

which gamete has the longer lifespan?

sperm

How does the oocyte move down the oviduct?

cilia in the ampulla and smooth muscle contraction of the oviduct

8 steps of fertilization

hyperactive motility

binding to ZP

acrosomal reaction

penetration of ZP

sperm-oocyte membrane fusion

sperm engulfed

decondensation of sperm nucleus

formation of male pronucleus

What surrounds the ZP?

cumulus cells

what is the ZP composed of?

3 glycoproteins

structural proteins of ZP

ZP1 & ZP2

binding protein of the ZP

ZP3

why must spem be able to travel through the cumulus cells?

cumulus cells surround the oocyte (egg) and are the first barrier the sperm must penetrate to achieve fertilization

What makes up the matrix around the cumulus cells?

hyaluronic acid

What enzyme on the sperm breaks down the hyaluronic acid?

hyaluronidase

When the sperm reaches the egg is it capacitated or acrosome reacted?

capacitated

What receptor does the sperm bind to on the ZP?

ZP3

What 2 sites make up the ZP3 receptor?

ZBR (zona binding region)

ARPR (acrosome reaction promoting region)

What happens when the sperm binds to the ZP?

acrosome reaction

What digests the ZP?

acrosin (enzyme in the acrosome)

what is the acrosome reaction?

membrane fusion occuring between the plasma membrane and the outer acrosomal membrane

what does the acrosome reaction lead to?

vesiculation of the two membranes (fusion)

releases the acrosome contents (acrosin)

exposes the fusion proteins on the equatorial segment

What binds to the oocyte plasma membrane receptors?

fusion proteins

What is released when sperm binds to oolemma?

cortical granules

What are the 2 blocks to polyspermy?

zona and vitelline block

What causes the MPN to form?

GSH (glutathione)

what helps to bind the oocyte to the plasma membrane

equatorial segment

what is polyspermy?

when multiple sperm try to penetrate the egg

what does the zona block do?

ZP modifies/changes/hardens due to contents of the cortical granules released from the cortical reaction

what does the vitelline block do?

oocyte plasma membrane changes after fusion so it’s unresponsive to subsequent sperm (won’t recognize fusion proteins)

what is male pronuclear formation

refers to the transformation of the sperm nucleus into a pronucleus, which will then unite with the female pronucleus to form the zygote’s diploid nucleus

what causes decondensation of DNA?

high levels of GSH causes disulfide bridges to break

what proteins are responsible for disulfide bridges? why is this important?

protamines

high condensed sperm

no PB means

immature egg

1 PB means

female ovulated

2 PB means

egg is fertilized

term for a fertilized oocyte

ootid

fusion of the MPN and FPN

syngamy

ootid undergone syngamy

zygote

organism in the early stages of development and doesn’t have recognizable appearance of that species

embryo

identifiable organism in uterus

fetus

Biological process embryo 'does'

cleavage (mitotic divisions)

term for embryonic cells

blastomeres

Term for an embryo with 4 blastomeres

4-celled embryo

When a blastomere can give rise to a new and identical embryo

totipotent

Embryo that has too many blastomeres to count

morula

what occurs in the morula

outer cells begin to compact more than those in the center

this forms 2 different groups of cells (inner and outer)

T/F cells up against the ZP are more compact than the ones in the middle

true

What happens to the size of the blastomeres as their number increases?

decreases

What happens to the outer cells of the morula?

compact

What types of junctions form between the outer cells?

tight

what does a morula become?

blastocyst

what do the tight junctions do?

prevent passage of fluid and ions (makes them travel through the cells instead of between)

what do the gap junctions allow for?

communication

what is pumped into the intercellular spaces? what follows

Na+

water

what does the accumulated water form?

fluid filled cavity called the blastocoele

What is the group of inner cells called?

ICM (inner cell mass)

What is the outer layer of cells called?

trophoblast

what happens after the blastocyst is formed?

more fluid accumulates

trophoblast cells produce enzymes

these enzymes break down the ZP

ZP weakens and breaks

blastocyst “oozes” out

order from ootid to hatched blastocyst

ootid

zygote

2-celled embryo

morula

early blastocyst

hatching blastocyst

hatched blastocyst

what eventually forms the placenta for gestation to occur

trophoblast

in the ootid, what is visible?

both PB

both PN