BMSZ (semi)
, Fertilisation ,
Assisted Reproduction
i.
Contraception
,129 -
Fertilisation & early embryo development
Embryogenesis metric
assy
division
(generic ;;Ywe%¥
In 2h
01 .
MISH n
↑ LH
h
In 4 sperm
☐
, complete M2
.
to
Female MS fertilisation
" Kicky
polar body
Zona pellucida ( glycoprotein coat ) & prevents polyspenny (not compatible with life in humans
)
-
protects oocyte as
goes through oviducts +
from species
entering oocyte & mediates species specific -
recognition
^
human
Mouse
egg
e
14µm thick human ↓
7pm
.
vs in vs mouse
mouse sperm < human ↓ from carbohydrate
ZP4
has extra
residues
Cumulus cells Protein cumulus cells
%¥¥☒
thin
(above ZP ,
penetrating it with their processes into
cytoplasm of egg)
Functions :
penetrate ZP it egg
form intracellular
junctions with
oocyte cell mem .
Male
head shape species but ubiquitous
→
varies across components
Drosophila bifurea has
largest sperm 16cm long)
✗ 20 longer
than animal → spembund
, Fertilisation
Requires various barriers :
small window
{
3 stages of fertilisation
1) sperm preparation facnsome reaction)
2) sperm binding fusion r
3) preventing polys penny (cortical reaction
1) Sperm preparation
-
CAPA CITATION
oviduct
•
in
mature
allows sperm to
acquire capacity
to
fertiliser making it less stable
by losing
• :
via
cholesterol , phospholipids A
r
glycoproteins on
surface causes in tail movement
( hyperactivation)
1) Sperm preparation
-
A CROSOME REACTION
induced
by progesterone
•
↓
proteolytic enzyme release
( eg hyaluronidase for pores @ outer acnsomal mem .
↓
expose acres in @ inner aowsomal membrane
↓
expose surface molecules for sperm
binding to ZP receptors
⑨ Izumo
1)
,Sequence of events in
fertilisation
} """ "
this order of events .
"""
(
on )
its side
↑ I
penvitaelline oolemq
space
Time lapse experiment by
:
by
ZP penetrated aerosome -
reacted sperm or not acw some -
intact sperm
( remains on ZP
surface )
2) Sperm binding
-
OOCYTE PLASMA MEMBRANE
sperm Renard enters perivitelline space and
immediately after fusion with oolema the tail stops beating
•
↓
sperm head binds on its side to
oocyte ( via Izumo 1
ligand on
sperm head with Juno on
egg) .
↓
microvilli on
oocyte mem .
engulf sperm
↓
swelling (fertilisation )
at point of there is
fusion
cone
,3) Preventing polys penny -
CORTICAL REACTION
cortical
•
granules from inside with plasma contents released into pen : space
egg fuse
mem .
or .
-
t proteases peroxidases
, ,
polysaccharides
As structure
of ZP (which prevents polyspenny )
-
=
Zona block
I
2
ways
✓↳
{
2-0Mt REACTION
/ MEMBRANE
BLOCK
Zohra BLOCK
slow block 2- P2 cleaved
Juno shed
receptor
gradually gum
• •
80 mem
plasma membrane
oligosaccharides
ZP 3 removes
.
other sperm
•
so
block also
•
cross-link other ZP proteins cannot bind
440min after sperm
entry) .
w
polyspenny can still take place 4 -2% in vivo
/ 10% in
vitro
sperm contribution to
zygote
•
whole sperm enters
oocyte in most mammals
Conly head in
golden hamsters
mt
destroyed
→ mt inherited
sperm zygote maternally
•
.
.
all
sperm centriole has different fates
•
:
-
in humans it
incorporates into
zygote r
organises
1st mitotic spindle µ -
cell → 2- cell
embryo)
A
rodents it not retained
-
in is .
Formation
of zygote
As sperm enters female
"
ca Spike → stimulates to continue meiosis 1st nucleus
→ →
firms
v1 (female pronucleus )
sperm undergoes dramatic transformation t
2nd polar
body
}
-
sperm nucleus decmclenses
nuclear mem
forms around sperm DNA 24h to male Dmt
-
reprogram
~
.
me
sperm DNA
actively demethylation
-
-
histones replace protamines in
sperm chromatin
✓ ↳ nuclear proteins that protect DNA and aid in
male pronucleus tightly packing it to make it fit in
sperm
head .
, 1st mitotic division
[post fertilisation ,
takes 18 -24h
]
1) dissolving of pronuclear envelope
2)
syngamy merging of gametic ( )
-
Ftm chromosomes on spindle
3) formation of 2- cell
embryo .
Cleavage
series
of rapid
divisions without cell
growth divisions are
reductive BLASTOMERES
( totipotent
)
-
I
so produce
cleavage timings (quicker development
can
As between mouse r human in
mice placenta
as all
as
cells
well
of
-
early embryogenesis
-
body
occur at same time
Compaction [takes 10h ] e- but independent → Polarisation
8- cell smooth starts @ 8- cell
stage each cell
gains polarisation to become
•
= •
then compaction
cells
flattened increases cell-to-cell contact epithelial like :
•
-
microvilli
confines
to
requires action E-cadherin p catenin microvilli @ outer apical surface
•
surface of
r - -
↓
¥÷÷¥ ☆ -
organelles @ outer apical region
embryo to
• •
allows
become
closely @ basal
-
nucleus inner
region
a
bonded
single entity
1
-
formation of tight junctions
cells continue to divide
↓
MORULA
( 16 cell
)
-
dinner ]
outer polarised cells
→ Allows
polar BLASTOCYST
a cells
formation
cavitation (blastocyst formation
•
ATP -
dependent pump system
: Nat
=
pumped into
blastocyst cavity ! Hwn in
by osmosis
↓
cavity expands
( BLASTOCOEL E)
↓ embryo now
essential differentiated
for proper development of ICM
into ICM t
at end
as inner polar cells remain one f-
a
troph ectoderm
t f
,Blastocyst implantation [day 8- a ]
hatches
embryo from
ZP with 1- 2d
after entering uterus .
survival obstacle
This step is a
significant as -
tz fail to
successfully implant
, L 30 -
Assisted reproduction
30.1
Understanding the female reproductive system
@ period :
endometrium 3mm
4- 5mm
small
follicles
@ tod after period :
follicles 11mm
@ 1 2d :
endometrium 9mm
follicles 14mm
@ Kid :
pre ovulating follicle 18mm
fertile mucous present (
in prep to let sperm into
.
uterus
sperm swims all the
way
into
fallopian tube
J
V
meet
has
ovary grown
a
big follicle
# egg released → picked up by
tube
follicle released fallopian
✓
follicle collapses down and cells
change
bÉmes CL
CL
very vascular
( ✗8
of kidney) since it produces a lot
of progesterone
↓
A endometrium
by stopping
its
growth starts secreting
+
proteins important for early
nourishment
pregnancy
.
, Fertilisation ,
Assisted Reproduction
i.
Contraception
,129 -
Fertilisation & early embryo development
Embryogenesis metric
assy
division
(generic ;;Ywe%¥
In 2h
01 .
MISH n
↑ LH
h
In 4 sperm
☐
, complete M2
.
to
Female MS fertilisation
" Kicky
polar body
Zona pellucida ( glycoprotein coat ) & prevents polyspenny (not compatible with life in humans
)
-
protects oocyte as
goes through oviducts +
from species
entering oocyte & mediates species specific -
recognition
^
human
Mouse
egg
e
14µm thick human ↓
7pm
.
vs in vs mouse
mouse sperm < human ↓ from carbohydrate
ZP4
has extra
residues
Cumulus cells Protein cumulus cells
%¥¥☒
thin
(above ZP ,
penetrating it with their processes into
cytoplasm of egg)
Functions :
penetrate ZP it egg
form intracellular
junctions with
oocyte cell mem .
Male
head shape species but ubiquitous
→
varies across components
Drosophila bifurea has
largest sperm 16cm long)
✗ 20 longer
than animal → spembund
, Fertilisation
Requires various barriers :
small window
{
3 stages of fertilisation
1) sperm preparation facnsome reaction)
2) sperm binding fusion r
3) preventing polys penny (cortical reaction
1) Sperm preparation
-
CAPA CITATION
oviduct
•
in
mature
allows sperm to
acquire capacity
to
fertiliser making it less stable
by losing
• :
via
cholesterol , phospholipids A
r
glycoproteins on
surface causes in tail movement
( hyperactivation)
1) Sperm preparation
-
A CROSOME REACTION
induced
by progesterone
•
↓
proteolytic enzyme release
( eg hyaluronidase for pores @ outer acnsomal mem .
↓
expose acres in @ inner aowsomal membrane
↓
expose surface molecules for sperm
binding to ZP receptors
⑨ Izumo
1)
,Sequence of events in
fertilisation
} """ "
this order of events .
"""
(
on )
its side
↑ I
penvitaelline oolemq
space
Time lapse experiment by
:
by
ZP penetrated aerosome -
reacted sperm or not acw some -
intact sperm
( remains on ZP
surface )
2) Sperm binding
-
OOCYTE PLASMA MEMBRANE
sperm Renard enters perivitelline space and
immediately after fusion with oolema the tail stops beating
•
↓
sperm head binds on its side to
oocyte ( via Izumo 1
ligand on
sperm head with Juno on
egg) .
↓
microvilli on
oocyte mem .
engulf sperm
↓
swelling (fertilisation )
at point of there is
fusion
cone
,3) Preventing polys penny -
CORTICAL REACTION
cortical
•
granules from inside with plasma contents released into pen : space
egg fuse
mem .
or .
-
t proteases peroxidases
, ,
polysaccharides
As structure
of ZP (which prevents polyspenny )
-
=
Zona block
I
2
ways
✓↳
{
2-0Mt REACTION
/ MEMBRANE
BLOCK
Zohra BLOCK
slow block 2- P2 cleaved
Juno shed
receptor
gradually gum
• •
80 mem
plasma membrane
oligosaccharides
ZP 3 removes
.
other sperm
•
so
block also
•
cross-link other ZP proteins cannot bind
440min after sperm
entry) .
w
polyspenny can still take place 4 -2% in vivo
/ 10% in
vitro
sperm contribution to
zygote
•
whole sperm enters
oocyte in most mammals
Conly head in
golden hamsters
mt
destroyed
→ mt inherited
sperm zygote maternally
•
.
.
all
sperm centriole has different fates
•
:
-
in humans it
incorporates into
zygote r
organises
1st mitotic spindle µ -
cell → 2- cell
embryo)
A
rodents it not retained
-
in is .
Formation
of zygote
As sperm enters female
"
ca Spike → stimulates to continue meiosis 1st nucleus
→ →
firms
v1 (female pronucleus )
sperm undergoes dramatic transformation t
2nd polar
body
}
-
sperm nucleus decmclenses
nuclear mem
forms around sperm DNA 24h to male Dmt
-
reprogram
~
.
me
sperm DNA
actively demethylation
-
-
histones replace protamines in
sperm chromatin
✓ ↳ nuclear proteins that protect DNA and aid in
male pronucleus tightly packing it to make it fit in
sperm
head .
, 1st mitotic division
[post fertilisation ,
takes 18 -24h
]
1) dissolving of pronuclear envelope
2)
syngamy merging of gametic ( )
-
Ftm chromosomes on spindle
3) formation of 2- cell
embryo .
Cleavage
series
of rapid
divisions without cell
growth divisions are
reductive BLASTOMERES
( totipotent
)
-
I
so produce
cleavage timings (quicker development
can
As between mouse r human in
mice placenta
as all
as
cells
well
of
-
early embryogenesis
-
body
occur at same time
Compaction [takes 10h ] e- but independent → Polarisation
8- cell smooth starts @ 8- cell
stage each cell
gains polarisation to become
•
= •
then compaction
cells
flattened increases cell-to-cell contact epithelial like :
•
-
microvilli
confines
to
requires action E-cadherin p catenin microvilli @ outer apical surface
•
surface of
r - -
↓
¥÷÷¥ ☆ -
organelles @ outer apical region
embryo to
• •
allows
become
closely @ basal
-
nucleus inner
region
a
bonded
single entity
1
-
formation of tight junctions
cells continue to divide
↓
MORULA
( 16 cell
)
-
dinner ]
outer polarised cells
→ Allows
polar BLASTOCYST
a cells
formation
cavitation (blastocyst formation
•
ATP -
dependent pump system
: Nat
=
pumped into
blastocyst cavity ! Hwn in
by osmosis
↓
cavity expands
( BLASTOCOEL E)
↓ embryo now
essential differentiated
for proper development of ICM
into ICM t
at end
as inner polar cells remain one f-
a
troph ectoderm
t f
,Blastocyst implantation [day 8- a ]
hatches
embryo from
ZP with 1- 2d
after entering uterus .
survival obstacle
This step is a
significant as -
tz fail to
successfully implant
, L 30 -
Assisted reproduction
30.1
Understanding the female reproductive system
@ period :
endometrium 3mm
4- 5mm
small
follicles
@ tod after period :
follicles 11mm
@ 1 2d :
endometrium 9mm
follicles 14mm
@ Kid :
pre ovulating follicle 18mm
fertile mucous present (
in prep to let sperm into
.
uterus
sperm swims all the
way
into
fallopian tube
J
V
meet
has
ovary grown
a
big follicle
# egg released → picked up by
tube
follicle released fallopian
✓
follicle collapses down and cells
change
bÉmes CL
CL
very vascular
( ✗8
of kidney) since it produces a lot
of progesterone
↓
A endometrium
by stopping
its
growth starts secreting
+
proteins important for early
nourishment
pregnancy
.
