Quiz 5

Question 1

fusion of a haploid spermatazoa w/ a haploid secondary oocyte to form one single diploid cell

Answer 1

Fertilization

Question 2

Position and state of ovum

Answer 2

Ovum in ampulla or AIJ of oviduct

Question 3

Cumulus cells

Answer 3

Present in sow
Absent in cow, mare, and ewe

Question 4

Encounter of sperm with ovum

Answer 4

Capacitation

Question 5

Fertilization Process

Answer 5

-Sperm form a loose, nonspecific attachment w/ zona pellucida
-Sperm cells bind to receptors on zona pellucida
-Bound sperm complete acrosome reaction in preparation for penetration of ZP
-Release of enzymes
-Acrosome reacted sperm can them penetrate ZP
-Sperm head fuses w/ vitelline membrane
-Cortical granules spill their contents into perivitelline space giving rise to zona reaction and vitelline block

Question 6

Union of pronuclei

Answer 6

Syngamy

Question 7

Duration of fertilization process

Answer 7

Varies from 12 to 24 hours

Question 8

Polyspermy

Answer 8

-Fertilization by more than one sperm cell
-Results in zygote with polyploidy (>2n)
-Incidence = 1-2%
-Increases with aged ovum
- Lethal condition

Question 9

Zygote

Answer 9

From syngamy to first division is completed

Question 10

Embryo

Answer 10

From 2-cell stage until differentiation is completed

Question 11

Fetus

Answer 11

From completion of differentiation to parturition

Question 12

Conceptus

Answer 12

Whole product of conception at any stage of development including placenta

Question 13

Process of cellular division without growth
Continues from first division to hatching of blastocyst

Answer 13

Cleavage

Question 14

Nourishment for embryo during cleavage

Answer 14

-Uterine secretions
-Cytoplasm of egg

Question 15

Process of cleavage

Answer 15

-First cleavage yields a 2-cell embryo
-Additional cleavages result in 4,8,16,32- cell etc.
-All divisions are miotic
-16- to 32- cell stage called morula
-Fluid begins to collect in intercellular spaces and cavity forms (blastocoele) to give rise to a blastocyst

Question 16

What 2 layers of cells are in the blastocyst

Answer 16

Trophoblast and inner cell mass

Question 17

Blastocyst stage

Answer 17

Zona pellucida will hatch
Period of elongation
Metabolic rate increases

Question 18

Twinning rate

Answer 18

beef= less than 1%
Dairy= 3.5%
Thoroughbred= 1 to 2 %
Draft-type= 3%

Question 19

Monozygotic (identical)

Answer 19

-Originate from single fertilized ovum
-More common in man and cattle
- 8 to 10 % of twins are identical
- 30% of twins in humans are identical
- Always same gender

Question 20

Mechanisms

Answer 20

-Separation of zygotic cells after first cleavage w/ each cell developing independently
- Formation of two inner cell masses w/ blastocyst