Transcript Lecture 16: Fertilization

Lecture 16: Fertilization
Animal Science 434
John J. Parrish
Capacitation
1951
Austin - rat
Chang - rabbit
Fertilization does not occur until several
hours after sperm are placed in the
uterus or oviduct
Chang Experiment - 1951
Ovulation
After
Before
Capacitation
The changes within sperm that confer
upon the sperm the ability to acrosome
react in response to the appropriate
stimulus.
 Zona Pellucida
 Cumulus Cells
 Follicular Fluid
Effect of Capacitation
Epididymal
Seminal
Plasma
+ and/or
Epididymal
Secretions
Ejaculated
Female
+
Tract
Capacitated
DF (BSP in Bovine)
Plasma Membrane
Decapacitation Factor – Stabilizes plasma membrane
and inhibits a premature acrosome reaction
Cholesterol
Acceptor
Plasma Membrane
BSP
Heparin
Cholesterol
Acceptor
Plasma Membrane
BSP
Heparin
Raft Migration
Zp binding
clustering
HCO3-
H+
BSP
Cholesterol
Acceptor
Heparin
Raft Migration
sAC
(+)
H+
HCO3cAMP
(+)
(+)
pHi
PK-A
(+)
PTK
(+)
(-)
Ptyr-Ptase
(-)
Protein Tyrosine Phosphorylation
Zp binding
clustering
Extracellular Space
Diffusion
CO2 + H2O
H2CO3
Carbonic Anhydrase
H+ + HCO3-
HCO3-
H+
BSP
Cholesterol
Acceptor
Heparin
Raft Migration
sAC
(+)
H+
HCO3cAMP
(+)
(+)
pHi
PK-A
(+)
PTK
(+)
(-)
Ptyr-Ptase
(-)
Protein Tyrosine Phosphorylation
Zp binding
clustering
Ca2+
ATP
ADP
Ca2+
ATP
ADP
Ca2+
Acrosome
Cholesterol
Acceptor
BSP
Heparin
Ca2+
Raft Migration
ADP
ATP
Ca2+
Ca2+
ATP
ADP
Ca2+
Acrosome
HCO3-
H+
Heparin
Ca2+
(+)
sAC
(+)
H+
BSP
Cholesterol
Acceptor
HCO3-
Ca2+
cAMP
(+)
(+)
pHi
PK-A
(+)
PTK
(+)
Ca2+
(-)
Ptyr-Ptase
(-)
Protein Tyrosine Phosphorylation
Acrosome
Capacitation
No change in sperm morphology
Motility change
– hyperactivation
cAMP
Power output
The Acrosome Reaction
Plasma Membrane
Acrosome
Nucleus
Fused Plasma
Membrane and
Outer Acrosomal
Membrane
Acrosin
Hyaluronidase
Modification
of the
Equitorial
Region
The Zona Pellucida
Sperm Interaction with the Zona
Attachment
Z
o
n
a
P
e
l
l
u
c
i
d
a
Binding
ZP3
Acrosome Reaction
Induction
Acrosome Reaction
Secondary Binding
Z
o
n
a
ZP2
ZP2
P
e
ZP2
l
l
u ZP2
c
i
d
a
Zona Penetration
Motility
Zona Pellucida
Sperm tract through zona pellucida
6-12 hr
18-24 hr
Maturation Promoting Factor
(MPF)
LH Surge
Metaphase Promoting Factor
Primary Oocyte
GVBD
Metaphase I
MPF
MPF
GV-Intact
PB-1
Ovulation
MPF
Metaphase II
MPF
Secondary Oocyte
Zona Pellucida
Oocyte
Ca2+
Ca2+
Ca2+
Ca2+
Perivitelline
Space
Zona Pellucida
Oocyte
Ca2+
Ca2+
Ca2+
Ca2+
Perivitelline
Space
Zona Pellucida
Oocyte
Ca2+
Ca2+
Ca2+
Ca2+
Perivitelline
Space
Zona Pellucida
Oocyte
Ca2+
Ca2+
Ca2+
Ca2+
Perivitelline
Space
Zona Pellucida
Oocyte
Ca2+
Ca2+
Ca2+
Ca2+
Perivitelline
Space
500
500
450
400
450
400
350
350
Calcium (nM)
Calciu m (nM)
Calcium Transients During Bovine Fertilization
300
250
200
150
250
200
150
100
50
100
50
0
0
0
10
20
30
40 50 60
Time (m in)
70
80
90
500
500
450
400
450
400
350
350
Calcium (nM)
Calcium (nM)
300
300
250
200
150
50
0
0
30
40 50 60
Time (min)
70
80
90
30
40 50 60
Time (min)
70
80
90
0
10
20
30
40 50 60
Tim e (m in)
70
80
90
150
50
20
20
200
100
10
10
300
250
100
0
0
Initiation of Calcium Pulse by
Soluble Sperm Component
DAG
Oocyte
PLCzeta
PIP2
IP3
Ca2+
Ca2+
Endoplasmic Reticulum
Zona Pellucida
Oocyte
Pronuclei
TII
Perivitelline
Space
PBII
AII
Ca2+
X
MPF
MII
Zona Pellucida
Oocyte
Decondensation
Pronuclei
Zygote
Pronuclei
TII
Perivitelline
Space
PBII
AII
Ca2+
X
MPF
MII
Zona Pellucida
Oocyte
Ca2+
Cortical
Granules
Perivitelline
Space
Zona Block to
Polyspermy
Zona Pellucida
Oocyte
Ca2+
Cortical
Granules
Perivitelline
Space
Zona Block to
Polyspermy
Blocks to Polyspermy
Species
1. Mammals
3. Invertebrates
Amphibians
Fish
Rabbits
4. Amphibians
Avians
1
2
3
4
Gamete Aging
Oocyte life span approx. 6 – 12 hours
after ovulation
Sperm life span approx. 24 – 48 hours
after ejaculation