Fertilization

Question 1

Where do sperm acquire maturity ?

Answer 1

Passage through epididymis

Question 2

Where does sperm gain maximal fertility?

Answer 2

Female tract (usually uterus)

Question 3

What are the steps of ejaculation?

Answer 3

Intromission

Sensory stimulation from glans penis (temp and pressure)

Afferent to spinal cord —> motor neuron (pudendal nerve)

Contraction of urethralis, bulbospongiosus and ischiocavernosus muscles

Expulsion of semen

Question 4

Where is semen deposited during natural mating in the cow, ewe, doe, and bitch?

Answer 4

Anterior vagina

Question 5

Where is semen deposited during natural mating in the mare?

Answer 5

Uterus

Question 6

Where is semen deposited during natural mating in the sow?

Answer 6

Cervix

Question 7

How are sperm lost once in the female tract?

Answer 7

Retrograde loss

Phagocytosis by neutrophils

Question 8

Where is capacitation completed?

Answer 8

Oviduct - sperm become hypermotile

Question 9

What must occur for a sperm to fertilize an oocyte?

Answer 9

Hyperactive motility 
Binding to ZP 
Acrosome reaction 
Spermatozoa penetrates oocyte 
Sperm-oocyte fusion 
Decondensation of sperm nucleus 
Male and female pronuclei form

Question 10

Sperm are continually delivered to the oviducts from what reservoir sites?

Answer 10

Cervix
UTJ

This extends the time in which fertilization can occur

Question 11

Where are sperm stored in the oviduct?

Answer 11

Isthmus

Question 12

What is the purpose of seminal plasma?

Answer 12

Mixing of sperm and seminal plasma coats the sperm with proteins that must be removed for max fertility

Question 13

What is capacitation?

Answer 13

Stripping of membrane proteins (from seminal plasma) by uterine factors

• over tail improves motility
• mover the mid-piece improves metabolism
• over the head allows binding to ZP

Resulting in hyper activated sperm in ampulla

Question 14

What initiates the acrosome reaction?

Answer 14

Binding to ZP

Plasma membrane over the acrosomal membranes fuses use acrosomal membrane —> vacuolation

Acrosomal enzymes can pass broth

Vesicles are sloughed off leaving inner acrosomal membrane and nuclear cap intact

Enters perivitelline space
Membranes fuse
Cortical reaction induced

Question 15

What is the cortical reaction?

Answer 15

Sperm head attaches to oocyte plasma membrane (vitelline membrane) and initiates block to polyspermy

ZP hardens
Vitelline membrane changes

Question 16

Where does fertilization take place at in the cow?

Answer 16

Ampullaisthmic junction

Question 17

What is syngamy?

Answer 17

Fusion of male and female pronuclei (forms zygote)

Question 18

What barriers prevent polyspermy?

Answer 18

Cumulus cells

Zona pellucida — oocyte cortical granules are released into the perivitelline space (cortical reaction)

Oocyte membrane

Question 19

What stages does a fertilized embryo go through prior to attachment?

Answer 19

Zygote

Two celled stage

Four celled stage

Eight celled stage

Morula

Early blastocyst

Hatching blastocysts

Hatched blastocyst

Question 20

Each blastomere is totipotent up the the ________ cell stage

Answer 20

8-16

Question 21

What is totipotent?

Answer 21

The ability of a single blastomere to develop into a fully formed individual animal

Question 22

How long does it take the zygote to travel from the uterine tubules to the uterus?

Answer 22

4 days

Question 23

What is freemartinism?

Answer 23

Male and female twins..

Anti mullerian hormone from male blocks formation of the Müllerian duct in the female
—> clitoral enlargment and brain changes like a male (male adult behavior)

Question 24

What is the shape of the ruminant hatched blastocyst? How is the mare different?

Answer 24

Ruminant= Filamentous thread-like

Mare = remains spherical