Development Of Nervous System Part1 Flashcards

1
Q

What is HCG? (Human chorionic gonadotropin)

A

HCG is the hormone which is released from cytotrophoblast and syncytiotrophoblast on corpus luteum to secrete more and more progesterone to implant the embryo in uterus until they are own capable of secreting progesterone and estrogen

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2
Q

Is there will be 2nd meiotic division if there will be no sperm?

A

No, when ovum will be released from graffian follicle it will already complete 1st meiotic division
But if there will be sperm only in that case when sperm will touch ovum the ovum will undergo 2nd meiotic division.

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3
Q

Stages of development in the first week of gestation?

A

Zygote 1 cell stage
Blastula 2-4 cell stage
Morula -12-16 cell stage
Differentiate into inner and outer cell mass (blastomere)
Zona Pellucida degenerate- fluid acculturated inner cell will form Embryoblast and outer trophoblast
(Blastocyst)
Outside villi are formed - the organized cells with nucleus are cytotrophoblast
The outer floating nucleus cells are syncytiotrophoblast
Trophoblast - only responsible to give rise to supporting layer’s+ placenta
Embryoblast - give rise to all structures and inside layers of embryo and fetus.

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4
Q

What will happen in 2nd week of gestation?

A

Embryoblast give rise to 2 layers
Epiblast-above present amniotic cavity
Hypoblast-below present yolk sac
There will be precordal plate (future mouth), help in differentiating cephalic and caudal end
The cells will degenerate longitudinal and form primitive streak and node as well
Then cells undergo and form trilaminar layers
Ectoderm- there will be thickening of cells and form neural plate, then will go downward and form neural groove and neural fold, and form the remamnants as neural crest cells. In this way the folds are closed and form neural tube with anterior neuropore ( 25th day of gestation fusion) and posterior neuropore (27th day of gestation fusion occur)
Mesoderm- the cells will go longitudinal and form notochord
Endoderm

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5
Q

Remanants of notochord in adult?

A

They are present as nucleus pulposus in the fibrous annulus of intervertebral disc.

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6
Q

Trilaminar layers will give rise to what in future?

A

Ectoderm- skin
Mesoderm- body wall, ribs, muscles
Endoderm - GIT
*Notochord present between mesoderm will give ruse to brain and spinal cord

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7
Q

Why folic acid is important to present in good amount in maternal blood?

A

Folic acid should be present in every reproductive age woman because if there will be deficiency the anterior or posterior neuropore will not close properly.
Anterior neuropore - cause anencephaly

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