Ecto, Endo, Mesoderm

[joonkimdds]

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Do i have to memorize what ectoderm, endoderm, and mesoderm become?

do u guys know all of it~? any easy way to memorize them?

 

[DMD to Be]

I memorized it. It's actually pretty simple. The ectoderm forms into the integumentary system, the lens and retina of the eye, and the nervous system. I think of it as the ectoderm is the outer most layer, so it forms our outer most layers. The endoderm will develop into the epithelial linings of the digestive and respiratory tracts, parts of the liver, pancreas, thyroid, and bladder lining, and intestinial mucosa. This is the "inner layer" The mesoderm develops into the muscular and skeletal systems, circulatory system, excretory system, gonads and the connective tissue. Everything that forms from the mesoderm connects the others. You know, like the circulatory system. I think of the mesoderm as the middleman. Hope this helps... I've seen several questions about this in my practice tests, and I'd be willing to bet it will be on the real DAT. Good luck to you!

 

[joonkimdds]

I memorized it. It's actually pretty simple. The ectoderm forms into the integumentary system, the lens and retina of the eye, and the nervous system. I think of it as the ectoderm is the outer most layer, so it forms our outer most layers. The endoderm will develop into the epithelial linings of the digestive and respiratory tracts, parts of the liver, pancreas, thyroid, and bladder lining, and intestinial mucosa. This is the "inner layer" The mesoderm develops into the muscular and skeletal systems, circulatory system, excretory system, gonads and the connective tissue. Everything that forms from the mesoderm connects the others. You know, like the circulatory system. I think of the mesoderm as the middleman. Hope this helps... I've seen several questions about this in my practice tests, and I'd be willing to bet it will be on the real DAT. Good luck to you!

Thanks.

By the way, could u explain this to me?
Kaplan blue book says Allantois is involved in respiration and excretion, and develops into the placenta in human. I thought Allantois become Umblical Cord while Chorion becomes placenta. Any idea?

 

[DMD to Be]

Thanks.

By the way, could u explain this to me?
Kaplan blue book says Allantois is involved in respiration and excretion, and develops into the placenta in human. I thought Allantois become Umblical Cord while Chorion becomes placenta. Any idea?

The placenta and umbilical cord are outgrowths of the 4 extra-embryonic membranes formed during development - amnion, chorion, allantois, and yolk sac. The allantois develops as an outpocketing of the gut. The blood vessels of the allantoic wall enlarge and become umbilical vessels, which will connect the fetus to the developing placenta.

That all came from the blue book. The allantois doesn't develop into the placenta. It just connects the fetus to the placenta via umbilical vessels. So, technically...yes the allantois does become part of the umbilical cord. So does the yolk sac.

 

[joonkimdds]

The placenta and umbilical cord are outgrowths of the 4 extra-embryonic membranes formed during development - amnion, chorion, allantois, and yolk sac. The allantois develops as an outpocketing of the gut. The blood vessels of the allantoic wall enlarge and become umbilical vessels, which will connect the fetus to the developing placenta.

That all came from the blue book. The allantois doesn't develop into the placenta. It just connects the fetus to the placenta via umbilical vessels. So, technically...yes the allantois does become part of the umbilical cord. So does the yolk sac.

I read the same thing from the blue book but if you look at the Bio Test #11 in that blue book, it says allantois become placenta. Does this mean this problem has an error? maybe it should've said umblical cord instead?

 

[lintydent]

Thanks.

By the way, could u explain this to me?
Kaplan blue book says Allantois is involved in respiration and excretion, and develops into the placenta in human. I thought Allantois become Umblical Cord while Chorion becomes placenta. Any idea?

There are four extraembryonic membranes: yolk sac, amnion, chorion and allantois.

The yolk sac is the site of blood vessel development....amnion encloses the embryo in a fluid-filled amniotic sac (acts as a cushion)....allantois and chorion form a respiratory organ for the embryo; the allantois forms into the umbilical cord and the chorion forms the placenta.

 

[slayerdeus]

Do i have to memorize what ectoderm, endoderm, and mesoderm become?

do u guys know all of it~? any easy way to memorize them?

The way I memorized it, might be easier and simpler:

Ectoderm: The senses, meaning nervous system and skin (touch) , eyes (sight), epithelium of mouth (taste) and nasal cavity (smell). Although I'm not sure about hearing, it could be part of the ectoderm as well.

Endoerm: All of the gross inner workings like endocrine glands (liver, pancreas) the digestive tract and respiratory tract

Mesoderm: everything else, including cirulatory, muscle, bones, urinary and reproductive system

 

[joonkimdds]

There are four extraembryonic membranes: yolk sac, amnion, chorion and allantois.

The yolk sac is the site of blood vessel development....amnion encloses the embryo in a fluid-filled amniotic sac (acts as a cushion)....allantois and chorion form a respiratory organ for the embryo; the allantois forms into the umbilical cord and the chorion forms the placenta.

so... r u saying that the Kaplan Blue Book #11 that says Allantois become umblical cord is an error?

if allantois and chorion form a respiratory oragan, and chorion forms the placenta, shouldn't the answer for the problem be Chorion?

Kaplan blue book #11 says
which of the following is involved in respiration and excretion, and develops into the placenta in human? and the answer is Allantois.

the answer says Choice A(Chorion) is incorrect because chorion lines the inside of the shell, and is a moist membrane that permits gas exchange.

 

[lintydent]

so... r u saying that the Kaplan Blue Book #11 that says Allantois become umblical cord is an error?

if allantois and chorion form a respiratory oragan, and chorion forms the placenta, shouldn't the answer for the problem be Chorion?

Kaplan blue book #11 says
which of the following is involved in respiration and excretion, and develops into the placenta in human? and the answer is Allantois.

the answer says Choice A(Chorion) is incorrect because chorion lines the inside of the shell, and is a moist membrane that permits gas exchange.

This is from Campbell (paraphrased):


The chorion completely surrounds the embryo and the other extraembryonic membranes and contributes to the formation of the placenta. The amnion is the first layer to surround the embryo in a fluid-filled cavity. Below the embryo which is the yolk sac which encloses another fluid-filled cavity...it forms the cells that will later migrate to the embryo. The allantois is an outpocketing that transports nutrients and oxygen FROM the placenta and the allantois is incorporated into the umbilical cord.

So YES Kaplan is WRONG. Plus if you google chorion or allantois they will associate chorion with placenta and allantois with umbilical cord...as did Campbell.

 

[DMD to Be]

I read the same thing from the blue book but if you look at the Bio Test #11 in that blue book, it says allantois become placenta. Does this mean this problem has an error? maybe it should've said umblical cord instead?

Yes, I would think it should say umbilical cord instead of placenta. I can't seem to find anywhere that says the allantois BECOMES the placenta.