Ovigenesis and fertilization

Question 1

Define oogenesis

Answer 1

formation and maturation of female gametes

Question 2

Name the 4 phases of oogenesis

Answer 2

1) mitotic division of primordial germ cells
2) Nuclear arrest
3) cytoplasmic growth
4) resumption of meiosis

Question 3

What is a dormant oocyte called?

Answer 3

dictyate oocyte

Question 4

How many oocytes mature in a sow

Answer 4

10-25

Question 5

When does the arrest of the primary oocyte occur?

Answer 5

In prophase 1

Question 6

When does arrest of the secondary oocyte occur?

Answer 6

In metaphase 2

Question 7

What kind of ovulators are production animals?

Answer 7

Spontaneous ovulators

Question 8

How does stimulation take place in induced ovulators?

Answer 8

Copulation stimulates neurons in the vagina and/or cervix with direct neurons to the hypothalamus

Question 9

What happens after neural stimulation?

Answer 9

1) neural stimulation results in the increase of GnRH and LH
2) LH initiates a sequence of events which leads to ovulation
3) The increase in LH causes an increase in P4 in the follicular fluid, Followed by PGF2alpha and PGE2.

Question 10

What can possibly hinder ovulation?

Answer 10

Inhibition of ovarian steroid or PGF2alpha secretion.

Question 11

What is the function of PGF2alpha

Answer 11

It ruptures lysosome like vesicles containing proteolytic enzymes, between the surface epithelium and surface albuginea.

Question 12

What is the function of proteolytic enzymes?

Answer 12

It degenerates tunica albuginea, theca externa and theca interna.

Question 13

What happens after the degeneration by the proteolytic enzymes?

Answer 13

1) plasmin acts as basement membrane
2) Wall of the follicle becomes thin and weak
3) Buldge (stigma) at the apex of the follicle is where the follicle will rupture.
4) When the follicle ruptures, follicular fluid, secondary oocyte and loosened granulosa cells will be extruded in the peritoneal cavity near the infundibulum.

Question 14

Where is the ovulation site in mares

Answer 14

Ovulation fossa

Question 15

Where is the ovulation site of all species except mares?

Answer 15

Anywhere on the ovarian surface

Question 16

What is the cumulus mass?

Answer 16

Loose matrix of cumulus cells around the tightly packed corona radiate cells which surrounds the oocyte. The oocyte is embedded in the cumulus mass.

Question 17

Granulosa cells is the sum of ….

Answer 17

cumulus + corona radiate

Question 18

Define gamete transport

Answer 18

Movement of viable gametes to the site of fertilization

Question 19

Where and how is the oocyte picked up?

Answer 19

In the infundibulum via ciliated cells, the cillia then moves the oocyte to the ampullary-isthmic junction.
The cillia also creates a directional flow of oviductal fluids which aids in transport.

Question 20

What is the most important mechanism for normal transport of an oocyte?

Answer 20

segmented, peristaltic contractions of the ampulla.

Question 21

What is the diffirent transport times of oocytes in the oviducts of the following animals? cattle, sheep, horse, swine.

Answer 21

Cattle= 90hrs
sheep= 72hrs
horse= 98hrs
swine= 50hrs

Question 22

What is the cause of the rapid phase transport of sperm?

Answer 22

Copulation-induced contractions, involving the smooth muscle in the cervix, uterus and oviduct.

Question 23

What stimulates these copulation induced contractions?

Answer 23

oxytocin and prostaglandins

Question 24

What follows the rapid transport phase of sperm?

Answer 24

Slower transport phase, which is the sustained transport of sperm to the oviduct.

Question 25

What is the greatest barrier to sperm transport?

Answer 25

Cervix

Question 26

What are the 2 types of cervical mucus in bovine?

Answer 26

1) sialomucins, low viscosity produced by cells in the basal portions of cervical folds.
2) Salfomucins, high viscosity produced by apical portions of the cervical folds.

Question 27

What causes sperm to be washed away from the cervix towards the vestibule?

Answer 27

Highly viscous sulfomucins

Question 28

What facilitates sperm transport through the cervix?

Answer 28

Low viscosity sialomucins

Question 29

name 2 functions of the cervical mucus

Answer 29

1) Increases sperm motility

2) filters out dead and abnormal sperm

Question 30

Retrograde loss of spermatozoa is _____ % of the deposited sperm.

Answer 30

18-30

Question 31

What serves as a barrier and filter for sperm?

Answer 31

uterotubal junction

Question 32

Name the first and second reservoir for sperm pooling.

Answer 32

1) cervix

2) isthmus

Question 33

When does sperm retain viability for longer?

Answer 33

When it is in contact with oviductal epithelium.

Question 34

What regulates the release of sperm?

Answer 34

Isthmic epithelium

Question 35

Name the site of fertilization.

Answer 35

Ampullary-isthmic junction

Question 36

Give the 5 major sequences of events when the sperm has been deposited into the female tract.

Answer 36

1) Immediate transport: includes retrograde loss, phagocytosis, entrance into the cervix/uterus
2) Cervix, removes abnormalities and nonmotile sperm
3) Uterus, capacitation initiated and phagocytosis
4) Oviduct, capacitation completed and sperm have a hyperactive motility
5) Fertilization, acrosome reaction, spermatozoon penetrates oocyte, male and female pronuclei form.

Question 37

Define polyspermy

Answer 37

Fertilization by more than one sperm

The zygote has a polyploidy nucleus

Question 38

Give the postcapacitation sequence of events that leads to fertilization

Answer 38

Hyperactive motility
Binding to zona pellucida 
Acrosomal reaction
Penetration of the ZP
Sperm-oocyte membrane fusion
Sperm engulfed
Decondensation of sperm nucleus
Formation of male pronucleus

Question 39

What does PGF2 alpha cause in the ovary and follicle

Answer 39

Contractions to expel the oocyte towards the infundibulum.