CADE EXAM 1: WEEKS 1-2 : BILAMINAR EMBRYO
overview of what goes on in bilaminar embryo development
fertilization
cleavege
blastocysts formation
implantation : burrow into uterus
week 1 : The process of Fertilization
Ovulation occurs before completion of oocyte maturation.
--> the secondary oocyte is released from ovary and is arrested in METAPHASE of
MEIOSIS 2.
-this secondary oocyte is released from the ovary and is swept up by the uterine tube
fimbriae Into the widest portion of the uterine tube called the ampulla.
the AMPULLA is where most fertilization will occur. the spermatozoa will travel through
the vagina, into the uterine tube up to the ampulla to bind to the secondary oocyte.
-the secondary oocyte is surrounded by:
(1) Zona pellucida: a thin transparent gelatinous layer of protein and polysaccharides.
(2) Corona radiata: several layers of the ovarian follicle.
both of which must be penetrated in order for fertilization to occur, sperm must be able
to chew through all of these layers in order to bind to oocyte
zona pellucida:
is a thin transparent gelatinous layer of protein and polysaccharides that surrounds the
secondary oocyte.
it is a zone around the oocyte.
,--> this will be important for sperm binding and will surround the developing embryo up
until the time for implantation. the embryo will have to hatch out of the zone pellucida
before it can adhere to the uterine lining.
corona radiata
-the secondary oocyte when released from the ovary will bring several layers of the
ovarian follicle. these layers of the ovarian follicle are the corona radiata.
capacitation
is the functional changes that sperm undergo.
--> this process happens in the female reproductive tract
this process enables them to fertilize a secondary oocyte.
-after capacitation you have a higher proportion of motile sperm
during the capacitation process, the acrosome reaction occurs.
acrosome reaction
changes in the membrane of the sperm that causes the release of enzymes
-the overlying plasma membrane becomes unstable when glycoprotein coat and
seminal plasma proteins are removed from plasma membrane overlying the sperm's
acrosome (modified lysosome)
the acrosome is shown in yellow, this region contains the enzymes that will be used to
chew through the corona radiata and the zone pellucida.
, -during the capacitation process changes are made to the acrosome to make the
overlying membrane to break down. this breakdown of the overly membrane will release
hyaluronidase and expose across to help the sperm to penetrate the corona radiata and
zone pellucida
steps in fertilization
A. sperm penetration of corona radiata and zona pellucida
B. next, fusion of plasma membranes of sperm an oocyte are necessary.
--> entry of a sperm into the egg triggers changes that prevent polyspermy (fertilization
of an egg by more than one sperm)
C. formation of MALE PRONUCLEUS: the tail and mitochondria of the sperm degrade,
so that all mitochondria in the embryo (and all mitochondrial DNA) come from mother.
once we get a sperm into the secondary oocyte, the head, nucleus of the sperm will
undergo certain changes. The DNA of the nucleus of the sperm will undergo changes
that will allow the DNA of sperm and DNA of egg to fuse.
D. Completion of second meiotic division of oocyte and formation of the FEMALE
PRONUCLEUS
E. once the male pronucleus from the nucleus of the sperm and the female pronucleus
intermingle by a process called syngamy you form a diploid zygote
THE TWO processes that occur in order to prevent polyspermy:
(1) cortical reaction: oocyte membrane becomes impenetrable to other sperm, occurs
on the cortex of the oocyte: outer regions of the oocyte.
overview of what goes on in bilaminar embryo development
fertilization
cleavege
blastocysts formation
implantation : burrow into uterus
week 1 : The process of Fertilization
Ovulation occurs before completion of oocyte maturation.
--> the secondary oocyte is released from ovary and is arrested in METAPHASE of
MEIOSIS 2.
-this secondary oocyte is released from the ovary and is swept up by the uterine tube
fimbriae Into the widest portion of the uterine tube called the ampulla.
the AMPULLA is where most fertilization will occur. the spermatozoa will travel through
the vagina, into the uterine tube up to the ampulla to bind to the secondary oocyte.
-the secondary oocyte is surrounded by:
(1) Zona pellucida: a thin transparent gelatinous layer of protein and polysaccharides.
(2) Corona radiata: several layers of the ovarian follicle.
both of which must be penetrated in order for fertilization to occur, sperm must be able
to chew through all of these layers in order to bind to oocyte
zona pellucida:
is a thin transparent gelatinous layer of protein and polysaccharides that surrounds the
secondary oocyte.
it is a zone around the oocyte.
,--> this will be important for sperm binding and will surround the developing embryo up
until the time for implantation. the embryo will have to hatch out of the zone pellucida
before it can adhere to the uterine lining.
corona radiata
-the secondary oocyte when released from the ovary will bring several layers of the
ovarian follicle. these layers of the ovarian follicle are the corona radiata.
capacitation
is the functional changes that sperm undergo.
--> this process happens in the female reproductive tract
this process enables them to fertilize a secondary oocyte.
-after capacitation you have a higher proportion of motile sperm
during the capacitation process, the acrosome reaction occurs.
acrosome reaction
changes in the membrane of the sperm that causes the release of enzymes
-the overlying plasma membrane becomes unstable when glycoprotein coat and
seminal plasma proteins are removed from plasma membrane overlying the sperm's
acrosome (modified lysosome)
the acrosome is shown in yellow, this region contains the enzymes that will be used to
chew through the corona radiata and the zone pellucida.
, -during the capacitation process changes are made to the acrosome to make the
overlying membrane to break down. this breakdown of the overly membrane will release
hyaluronidase and expose across to help the sperm to penetrate the corona radiata and
zone pellucida
steps in fertilization
A. sperm penetration of corona radiata and zona pellucida
B. next, fusion of plasma membranes of sperm an oocyte are necessary.
--> entry of a sperm into the egg triggers changes that prevent polyspermy (fertilization
of an egg by more than one sperm)
C. formation of MALE PRONUCLEUS: the tail and mitochondria of the sperm degrade,
so that all mitochondria in the embryo (and all mitochondrial DNA) come from mother.
once we get a sperm into the secondary oocyte, the head, nucleus of the sperm will
undergo certain changes. The DNA of the nucleus of the sperm will undergo changes
that will allow the DNA of sperm and DNA of egg to fuse.
D. Completion of second meiotic division of oocyte and formation of the FEMALE
PRONUCLEUS
E. once the male pronucleus from the nucleus of the sperm and the female pronucleus
intermingle by a process called syngamy you form a diploid zygote
THE TWO processes that occur in order to prevent polyspermy:
(1) cortical reaction: oocyte membrane becomes impenetrable to other sperm, occurs
on the cortex of the oocyte: outer regions of the oocyte.
