Embryology | Fertilization, Cleavage, Blastulation
Summary
TLDREste vídeo comienza una serie sobre embriología, explicando desde el final de la fertilización hasta el desarrollo del primer día. Se detallan las etapas clave como la ovulación, fertilización, cleavage y blastocystisación. Se discuten los cambios en la anatomía femenina, la liberación de hormonas y el proceso de capacitación del espermatozoide. Además, se explora la transformación del zygote en un blastocystis y la diferenciación de las células en la masa embrionaria y la trophoblasto, esenciales para el desarrollo del embrión y la placenta.
Takeaways
- 📅 La serie de embriología comienza después de la fertilización, que se discute en una lista de reproducción.
- 🌱 Se abordan los desarrollos desde la fertilización hasta la segunda semana, incluyendo la gastrulación.
- 🔎 Se conecta la anatomía uterina con la fisiología, destacando la importancia de la ovulación y la fertilización.
- 🧪 Se describe el ciclo menstrual femenino, con énfasis en la liberación de hormonas como la gonadotropina luteinizante (LH).
- 🤝 La ovulación ocurre alrededor del día 14 o 15 del ciclo menstrual, desencadenando la liberación de un óvulo.
- 🏋️♂️ La fertilización se produce en la ampolla del trompo de Falopio, donde el óvulo y el espermatozoide se encuentran.
- 🌟 La fusión del espermatozoide y el óvulo da lugar a un cigoto, que contiene 46 cromosomas (23 de cada progenitor).
- 📈 El cigoto comienza a proliferarse rápidamente a través de la cleavage, formando dos, cuatro, ocho y dieciséis células.
- 🌐 Se forma la morula, una bola hueca de células, a medida que el número de células aumenta.
- 🌱 La morula se convierte en un blastocisto a través del proceso de blastulación, diferenciando las células en masa embrionaria y tropoblástica.
Q & A
¿Cuál es el objetivo de la serie de videos de embriología que se menciona en el guion?
-El objetivo de la serie es comenzar desde el final de la fertilización y seguir el desarrollo del embrión hasta su completitud.
¿Cuál es el primer evento que se discute en la serie de embriología?
-El primer evento discutido es la fertilización, que se menciona que se puede encontrar en un playlist de reproducción.
¿Cuál es la secuencia de desarrollo que se abordará en el primer video de la serie?
-El primer video cubre el desarrollo desde la fertilización hasta la primera semana, incluyendo la gastrulación.
¿Qué hormona se libera alrededor del día 14 o 15 del ciclo menstrual femenino y qué desencadena?
-Se libera la hormona luteinizante, que desencadena la ovulación y la producción de fluidos en el ovario.
¿Qué es el graafian follicle y qué contiene?
-El graafian follicle es una bolsa que contiene el óvulo y se prepara para la ovulación, listo para liberar un óvulo secundario.
¿Qué fase del meiosis está atrapado el óvulo secundario después de la ovulación?
-El óvulo secundario está atrapado en la fase de metaphase del meiosis II después de la ovulación.
¿Qué proceso debe pasar el espermatozoide antes de poder fecundar el óvulo?
-El espermatozoide debe pasar por la capacitación, un proceso en el cual se eliminan ciertas moléculas de colesterol de su cabeza.
¿Qué sucede cuando el espermatozoide toca el óvulo durante la fertilización?
-Cuando el espermatozoide toca el óvulo, se activa y comienza a liberar enzimas que lo ayudan a perforar la membrana del óvulo y fusionar sus núcleos.
¿Cuál es la secuencia de divisiones celulares que sigue el zygote después de la fertilización?
-El zygote pasa por la cleavage, dividiéndose en dos, cuatro, ocho y luego dieciséis células, formando una morula.
¿Qué proceso transforma la morula en un blastocisto?
-El proceso de blastulación transforma la morula en un blastocisto, donde se forman la cavidad fluida y los grupos de células que eventualmente se convertirán en la tropoblasta y el embrioblasto.
¿Qué se denomina a la masa celular interna del blastocisto y qué papel desempeña?
-La masa celular interna se denomina embrioblasto y es la que eventualmente dará lugar al embrión humano.
¿Qué se convierte en la tropoblasta y qué función cumple?
-La tropoblasta se convierte a partir de la masa celular externa y tiene la función de formar parte de la placenta.
Outlines
🌟 Introducción a la serie de embriología
El vídeo comienza con una introducción a la serie de embriología, explicando que se iniciará desde el final de la fertilización. Se recomienda ver un vídeo previo sobre fertilización antes de continuar. Se menciona que se omitirán algunos detalles y se centrarán en el desarrollo durante la primera semana, pasando por la gastrulación y la formación del sistema nervioso. Se destaca la importancia de comprender la anatomía y la fisiología antes de abordar los eventos celulares, y se describe brevemente la anatomía uterina femenina, incluyendo la vagina, el cuello uterino, el cuerpo del útero, los ovarios y las trompas de Falopio. Se menciona que la fertilización ocurre en la ampolla de la trompa de Falopio.
🔬 Proceso de ovulación y liberación de hormonas
Se describe el proceso de ovulación y la liberación de hormonas durante el ciclo menstrual femenino. Se explica que alrededor del día 14 o 15, el cuerpo libera una hormona llamada hormona luteinizante (LH), que es estimulada por el hipotalamo a través de la liberación de gonadotropina liberadora de hormonas (GnRH). La LH estimula al ovario a producir fluido y a presionar la folículo de Graaf, lo que lleva a la ovulación. Se describe cómo la ovulación ocurre y cómo el óvulo se mueve hacia la ampolla de la trompa de Falopio, listo para la fertilización.
🤝 Fertilización y formación del cigoto
El vídeo detalla el proceso de fertilización, comenzando con la unión del óvulo y el espermatozoide en la ampolla de la trompa de Falopio. Se explica que el espermatozoide debe capacitarse, eliminar ciertas moléculas de colesterol y adherirse a receptores ZP3 en la superficie del óvulo para poder penetrar. Una vez que el espermatozoide toca el óvulo, se activa y libera enzimas que le permiten perforar la membrana del óvulo. El núcleo del espermatozoide se fusiona con el del óvulo, creando un cigoto con 46 cromosomas. Se describe el proceso de clevaje, donde el cigoto se divide repetidamente formando dos, cuatro, ocho y dieciséis células, hasta llegar a la morula, que es un conjunto de células en forma de bola hueca.
🌱 Desarrollo desde la morula hasta el blastocisto
Se describe el proceso de blastulación, donde la morula se transforma en un blastocisto. Se menciona que las células de la morula comienzan a compactarse y a agruparse, formando una estructura con células en el borde y un grupo de células en el centro. El blastocisto tiene una cavidad llena de fluido y dos tipos de masas celulares: la masa celular interna, que se convertirá en el embrión, y la masa celular externa, que se convertirá en el tropoblastoplasma. Se explica que el tropoblastoplasma se especializa en el citotrofoblasto y el siniciclo tropoblastoplasma, mientras que la masa celular interna se desarrolla en el blastodisco. Se resumen los pasos clave que ocurren durante la primera semana, incluyendo la ovulación, la fertilización, el clevaje, la blastulación y la especialización de las masas celulares.
Mindmap
Keywords
💡Fertilización
💡Citocinesis
💡Morula
💡Blastocisto
💡Masa interna de células
💡Masa externa de células
💡Tropoblas激
💡Discos bi y trilaminar
💡Implantación
💡Ciclo menstrual
Highlights
Embryology series begins with the end of fertilization.
Development within the first week starts post-fertilization.
Anatomy correlation is crucial for understanding embryology.
Luteinizing hormone triggers ovulation around day 14 or 15 of the menstrual cycle.
Estrogen levels play a role in the release of luteinizing hormone.
Ovulation involves the release of a secondary oocyte from the ovary.
The secondary oocyte is in metaphase of meiosis II, awaiting fertilization.
Sperm cells undergo capacitation to prepare for fertilization.
Fertilization occurs in the ampulla of the fallopian tube.
The zygote is formed by the fusion of 23 maternal and 23 paternal chromosomes.
Cleavage is the process of cell division from zygote to morula.
The morula is a hollow ball of cells with no internal structure.
Blastulation is the transformation of the morula into a blastocyst.
The blastocyst has an inner cell mass and an outer cell mass.
The inner cell mass will develop into the embryo, while the outer cell mass will form the placenta.
The embryoblast will further develop into the bilaminar disk.
The trophoblast will differentiate into the cytotrophoblast and syncytiotrophoblast.
Transcripts
iein engineers what we're gonna do in
this video is we're gonna begin our
embryology series okay so if you guys
haven't already we're gonna start from
the end of fertilization which is on a
reproductive playlist if you guys
haven't seen that already go watch that
first we're not going to go into a ton
of detail on that we're kind of just
going to skip over pieces and begin the
development within the first week then
after that what we'll do is we'll go
into the next video which is going to be
the development up until the second week
right so we're gonna go for gastrulation
then we'll have another video what we're
going to the development during up to
week three which is gonna involve dinner
elation process and then we'll discuss
the the formation of the nervous system
and we'll just continue to keep going
from there until the development of the
entire embryo alright so let's go ahead
and get started I'm user so let's go
ahead and get started then so first off
we have to talk about before we kind of
get into all the cellular events I want
us to really kind of correlate our
Anatomy with kind of the bigger picture
then we'll get down to the cellular
events so if you guys remember from the
fertilization video just a little bit
about your uterine anatomy right so very
simple here there's gonna be the vagina
they also call it the sheath right then
you're gonna have this portion right
here right which is called the cervix of
the uterus then we'll kind of get into
the body of the uterus right here up
this top like portion here which is kind
of rounded out like that that's gonna be
the fundus of the uterus and then here
you're gonna have your fallopian tubes
right and then at the end of the
fallopian tube you kind of have this
little dilated region right there that's
called the ampulla of the fallopian
tubes that's where fertilization is
supposed to occur right then you got
your little fingers little same brain
right and then after that you got the
ovaries right so what's important is
that an order for us to really kind of
talk about the cellular events we have
to understand the physiology going into
this so what happens usually around day
14 or day 15 of a female's menstrual
cycle right I'm sorry
they start to release a specific type of
hormone right called luteinizing hormone
so if you guys remember here let's draw
like a little diagram here we're gonna
have this guy but you guys remember this
diagram it's pine grain into your brain
right now we're gonna have
the hypothalamus with the poster
pituitary and anti pituitary that's not
nutsacks okay so just remember that now
what happens the hypothalamus starts
releasing specific types of neuro
peptides what are these neuro peptides
called they're called ganado tropen
releasing hormone and then what is gonna
a - open releasing woman do lots of it -
it stimulates the anterior pituitary
what does it tell the anterior pituitary
to do it tells it to start secreting
large amounts of luteinizing hormone
alright and this is also kind of playing
a role not just with the GnRH but if you
guys remember a little bit back from
you're kind of the dimensional
physiology
there's also another very big trigger
here and that's going to be a sturgeon
if you guys remember that positive
feedback cycle when estrogen levels
increase again right during the second
time that's also a big stimulator of
luteinizing hormone as well all right
anyway luteinizing hormone it's released
it gets into the blood goes down to the
over what does it do
well if you guys remember it tells the
ovary to kind of start producing a lot
of fluid alright so it tells the ovary
start making a lot of fluid but
pressurize that follicle because
remember we have that graafian follicle
which is the guy who's gonna have that
secondary oocytes what does he do he
triggers the release of certain types of
prostaglandins to dilate the vessels to
increase a lot of the leakiness out of
the capillaries around that graafian
follicle and activate certain types of
enzymes metalloproteinase is to break
down the connective tissue around it and
guess what that helps helps to pop that
little OA site out and then what happens
is the fimbriae they get all kinds of
cool and they start kind of moving that
actual oh a site towards what the
ampulla then this little oh a site here
we're going to draw it right here and
here is going to be the corona radiata
around it it gets popped out here right
so now that's our secondary oocytes I
think eyes remember I talked about it
and the kind of the whole ovulation
cycle that this is the secondary oocyte
what that means is if it's are
undergoing meiosis one and it's getting
ready to go into meiosis
- right it's getting ready to finish
meiosis - but it hasn't yet what stage
is it particularly in well if you guys
remember we said that once it's ovulates
it's stuck in a specific phase it's a
secondary Oh a site in metaphase -
that's an important thing to remember
secondary oocytes stuck in metaphase -
the reason why is it's waiting for a
sperm cell to touch it and then once it
does it says oh what I need is here I'm
gonna go ahead and finish meiosis to get
myself prepared for this nucleus from
the sperm cell and then I'm gonna fuse
with it so it's waiting and waiting and
who is awaiting on it's waiting on the
lucky son of a gun
right who gets the sperm cells where
they need to go and what happens is the
sperm once it's ejaculated it goes into
the vagina up through the cervix of the
uterus up through the body it makes its
way through the fallopian tubes and it
meets that nice little secondary oocytes
phase - at the ampulla all right and it
says hey I want to go ahead and touch
you now not in a creepy way though
alright so it goes ahead and it touches
it and then guess what starts happening
well let's go ahead and dig into that so
what we're gonna do is we're gonna
imagine that these guys are touching one
another right here in this kind of like
zone we're going to blow it up and we're
gonna take a look see so now we're
blowing it up here and here we're gonna
have that egg right so we have that
secondary oocytes stuck in metaphase -
this is the one then we got that sperm
cell and that sperm cell is coming over
here to meet this egg alright but in
order for it to be able to touch it you
guys remember it has to go through a
process called capacitation where has to
clean off a bunch of cholesterol
molecules and things off of the head of
it and then it has to attach to a
specific type of protein on the surface
and what is this protein if you remember
we have what's called zp3 receptors and
these zp3 receptors are really important
because once the actual sperm touches so
zp3 receptors once the sperm cell
touches it it activates the sperm cell
and then the head of the sperm cell whew
with the zone with the oocytes membrane
starts releasing a bunch of different
enzymes lysosomes hydrolytic enzymes
from its acrosome and it starts
burrowing its way through this then what
it does is it releases its nucleus you
see this little green guy it releases
its nucleus into the cytoplasm so here's
going to be this nucleus now in the
nucleus you know that there's
chromosomes right 23 chromosomes are
going to be in the sperm cell nucleus
and 23 chromosomes are going to be in
d.o.a sites nucleus well what happens is
let's see here 23 are gonna be paternal
and 23 of the other chromosomes are
going to be maternal these are going to
fuse when they fuse how many you gonna
get was 23 plus 23 it's 46 right so
you're gonna get 46 chromosomes now and
this is going to be a diploid cell but
we're also going to call it as I go so
again how many chromosomes 23 plus the
23 23 maternal 23 paternal 46 total
chromosomes and this is going to give us
our zygote now it's pretty amazing when
you think about it that from this one
cell this one cell we're actually gonna
be able to make an entire human body
that's pretty amazing so how does this
happen this zygote guess what
it starts undergoing lots and lots of
lots of proliferation so it starts going
through achieve one sg2 mitosis and just
starts replicating and replicating and
replicating what is that call whenever
it starts replicating and making two
cells then four cells then eight cells
then sixteen cells
that's called cleavage so it's very
simple we've already talked about
fertilization now what do we have to go
through we have to go through a bunch of
stages called cleavage so it's very
simple now now it's just a matter of
counting it up now what I'm gonna do is
I'm going to divide this cell it was
once one cell guess what I'm gonna do
now I'm gonna now have two cells now
here's the important thing to remember
remember I told you that this pink
membrane had a protein called the zona
pellucida three receptor that pink
protein is called the zona pellucida so
you're gonna have it in fertilization
you're gonna have it in the zygote and
you're
so gonna have it in this cell where it
divides what's this cell called this is
now called the two cell stage it's very
simple right so zygote you're gonna go
into the two cell stage guess what it's
then gonna do then it's then gonna
divide again it's gonna go from two
cells and you're gonna double that so
now it's going to be four cells so let
me do this now so there is going to be
four cells so this is the four cell
stage then what I bet you already
guessed it it's going to divide again
and it's going to turn into the eight
cell stage and then what do you think
it's going to go to after that it's
gonna go to the sixteen cell stage so
throughout that process now if you
imagine we're gonna have eight cells
here and then before you know we're not
gonna draw in all sixteen cells here
what you know here is that you're gonna
have tons and tons and tons of cells and
what this is gonna do is it's going to
form a kind of structure which is very
interesting what do I mean okay you're
gonna have these cells and they're going
to be surrounding the entire thing
surrounding this entire structure right
so it's entire circle you have these
cells surrounding it but inside the
center of it is hollow there's nothing
in there okay so if you were to imagine
let's imagine I took like a
cross-section here here's going to be
all the cells right forming the outer
coat
there's our cells forming the outer coat
but inside of this there's nothing it's
completely Hollow what do we call this
anything from 16 cells and up until we
get our blastocyst we call this the
marula so we call this one the marula
and this is basically going to be a
hollow ball of cells which is going to
be 16 or + cells
and what they call these they'd like to
give these cells a special name these
little circular blue cells here once
it's at the level of the marula they
call these blastomeres blasto mears okay
so that's important to remember now from
here what's gonna happen then okay so
now we have this marula right the marula
guess what it starts to do it starts to
take the cells right you have the cells
right here forming the edge what's going
to happen is a bunch of the cells in the
center there's gonna be a bunch of cells
that start compacting towards one edge
alright so you're gonna have the cells
lining the edge of this cell so let's do
it like this here you're gonna have
these cells they're gonna be kind of
lining the edge and they're gonna form
one type of cell structure that's very
important because this helps to go on
and form a part of the placenta okay
then another group of the cells around
that are gonna group towards one side
and kind of clump together let's do that
in a different color so that we don't
confuse this let's do this in the screen
here now we're gonna have these other
cells and they're going to be kind of
grouping together here and now we had a
hollow ball now what we do is we have a
cell lining around the edge and we had
to have just a bunch of group of cells
just clumped together in this one edge
over here what do we call this this is
going to be our blastocyst so the
process of what we're going from the
marula into the blastocyst is your blast
chelation process so now what do we have
here we're gonna have our blast
chelation
and we're gonna form here our blastocyst
which is so darn cool now within the
blastocyst you're gonna have this fluid
filled cavity so it's going to be all
fluid in here right
but then this group right here this
bunch of cells that are going to be kind
of clumped here together
this becomes a specific thing right we
call this part here the inner cell mass
okay and then the cells around the edge
or the periphery of it this is going to
be called D and very simple outer cell
mass now what happens is these cells
they start to differentiate and become
more functional right and what happens
is they become a little bit more
differentiate a little bit more
functional and then they become a
different type of name we just like to
change names for things all the time so
now what happens they continue to
differentiate continue to develop and
now that outer cell mass becomes a
specific type of thing which we call the
trophoblast so now this outer cell mass
is now what we call a trophoblast
becomes a little bit more differentiated
a little bit more specialized and we
call this the trophoblast
then we had that inner cell mass it
starts to become more specialized and
more differentiated and it turns into a
specific thing which is going to be
important and this is going to be called
the embryo blast this is called the
embryo blast so all I want you to really
know is the outer cell mass becomes the
trophoblast and the inner cell mass
becomes the embryo blast why is that
important because guess what eventually
the trophoblast becomes which we're
going to talk about next
it didn't differentiate into two other
specialized layers one is going to be
called the Saito trophoblast which we'll
talk about and the other one is to be
going to be called the syncytium
trophoblast the embryo blast guess what
its gonna start developing into it's
gonna start developing into your by
lemon or disk so and we'll talk about
how that happens but this is going to
start converting into your bi laminar
disk so within this first week right
that we've talked about what happened we
had ovulation was the first step right
so let's go ahead and mark out down our
steps first step was ovulating right
second step was fertilization okay and
that was here this was here and then
continuing on down here this is still
fertilization right so this is still the
fertilization step then what happened
from all the way from the zygote all the
way until the sixteen cell stage this
was all called cleavage so we'll write
that down that was the third step okay
then what happened after that then the
next thing is the marula converted into
the blastocyst okay that's going to be
the fourth stage so the fourth step is
going to be blast elation then after
that the blastula became more
specialized and converted into a
trophoblast which used to be the outer
cell mass and the embryo blast which we
used to become d which used to be the
inner cell mass then they will become
even more specialized in the embryo
blast become the bilaminar disk which is
going to be the EPI blast and the hypo
blast which we'll talk about and the
trophoblast is going to become the Saito
trophoblast and this is serial blast
this is important because these help to
be able to make to your structures like
the placenta okay whereas the embryo
blast is gonna make the embryo right so
this will then go from the by laminar to
the Tri laminar and that will help us to
make our entire embryo so that's why
this is so important this is generally
occurring within the first week
what we'll do next is we'll take this
truffle blast excel with the embryo
blast and we'll talk about how it
sprouts these little things we'll talk a
little bit more about this in seetio
trophoblast with the villi and how it
breaks through the zona pellucida and
then we'll talk a little bit more about
the embryo blast and how that converts
into the bilaminar disk alright so we'll
talk about that in the next video
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