Lecture 16: Fertilization
Animal Science 434 John J. Parrish
Capacitation Chang Experiment - 1951
1951 n 100
o
i Ovulation
t
Austin - rat a 80
z
i
l
i
t
Chang - rabbit r 60 After Before
e
F
Fertilization does not occur until several t 40
n
e
hours after sperm are placed in the c r 20
e
uterus or oviduct P 0 -2 -1 0 2 4 6 8 Time of Insemination (hr relative to ovulation)
Effect of Capacitation Capacitation Epididymal Ejaculated Capacitated
The changes within sperm that confer upon the sperm the ability to acrosome react in response to the appropriate Seminal Plasma stimulus. Female + + and/or Tract Zona Pellucida Epididymal Secretions Cumulus Cells Follicular Fluid
1 Model of Capacitation GAG D F D F
Acrosome Acrosome
Nucleus Nucleus
Cytoplasm Cytoplasm
Plasma Membrane Plasma Membrane
D F Chol-Acceptor GAG Capacitation Ca2+ Cholesterol No change in sperm morphology Motility change – hyperactivation
Acrosome Ca2+
Nucleus pH Activity of cAMP Enzymes cAMP Cytoplasm Power output
Plasma Membrane
Plasma Membrane Fused Plasma Membrane and Outer Acrosomal Membrane
Acrosin Acrosome Hyaluronidase
Nucleus Modification of the Equitorial Region
2 The Zona Pellucida Sperm Interaction with the Zona
Attachment Z o n a Binding P e ZP3 l Acrosome Reaction l Induction u c Acrosome Reaction i d a
Z Secondary Binding Zona Pellucida o ZP n 2 a ZP2 P Zona Penetration e ZP l 2 l u ZP2 c Motility i d a
6-12 hr
18-24 hr
Sperm tract through zona pellucida
3 Maturation Promoting Factor Zona Pellucida LH Surge (MPF) Oocyte Metaphase Promoting Factor 2+ Primary Oocyte GVBD Ca Metaphase I Ca2+
MPF MPF Ca2+ GV-Intact Ca2+ PB-1
Ovulation MPF MPF Perivitelline Space Metaphase II Secondary Oocyte
Zona Pellucida Zona Pellucida Oocyte Oocyte Ca2+ Ca2+ Ca2+ Ca2+
Ca2+ Ca2+
Ca2+ Ca2+
Perivitelline Perivitelline Space Space
Zona Pellucida Zona Pellucida Oocyte Oocyte Ca2+ Ca2+ Ca2+ Ca2+
Ca2+ Ca2+
Ca2+ Ca2+
Perivitelline Perivitelline Space Space
4 Calcium Transients During Bovine Fertilization Initiation of Calcium Pulse by
500 500 450 450 Soluble Sperm Component 400 400 ) ) 350 350 M M 300 300 (n (n
250 250 um i 200 200 c l
a 150 150 Calcium C 100 100 50 50 DAG 0 0 0 10 20 30 40 50 60 70 80 90 0 10 20 30 40 50 60 70 80 90 Oocyte PIP Time (m in) Time (min ) PLCzeta 2 500 500 IP 450 450 3 400 400
) 2+ 350 ) 350 Ca nM
300 nM 300 ( 250 ( 250 ium
cium 200 200 l alc
Ca 150 150 C 100 100 50 50 2+ 0 0 Ca 0 10 20 30 40 50 60 70 80 90 0 10 20 30 40 50 60 70 80 90 Time (min) Time (m in) Endoplasmic Reticulum
Sperm Receptor - Calcium Zona Pellucida Oocyte Pulse Initiation
PLC Ca++ IP3 ER Pronuclei
Ca2+ AII TII MXPF Perivitelline MII Space PBII
Zona Pellucida Zona Pellucida Oocyte Oocyte Decondensation Ca2+
Pronuclei Zona Block to Cortical Zygote Granules Polyspermy
Pronuclei
Ca2+ AII TII MXPF Perivitelline MII Perivitelline Space PBII Space
5 Zona Pellucida Blocks to Polyspermy Oocyte
Species Ca2+ 1. Mammals 1 3. Invertebrates Zona Block to Amphibians Cortical Fish 2 Granules Polyspermy Rabbits
4. Amphibians 3 Avians 4
Perivitelline Space
6