L5 Flashcards by Asma 1

Hello

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Organogenesis happens during

Gastrulation

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At the end of the embryonic period two things have happened what are they

1- main organ systems are formed
2-external body form is recognizable

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What induces the ectoderm to form the neural plate?

Then notochord

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Cells of the neural plate make up the

Neuroectoderm

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The neural plate will expand towards ___ and folds ___

Primitve streak, dorsaly

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By the end of the 3rd week, the lateral edges of the neural plate forms the

Neural folds

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By the end of the third week, The middle region depresses and forms

Neural groove

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Fusion begins at which region and how does it proceeds. What does it form

Cervical region, cranially and caudally
Neural tube

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What form the neural tube

Fusion of the neural plate

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Which cells give rise to the neural tube?

Neuroectoderm induced by notochord

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Folding/ closing begins at the end of which week

3rd week

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If closure of the caudal pores fail, what might result

Spina bifida

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The notochord induces the ___ to form the ___ which makes up the ___ to make the __ and ___

Ectoderm
Neural plate e
Neuroectoderm
Neural crest and neural tube

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until the fusion is complete, the cephalic and caudal end of the neural tube communicates with

The amniotic cavity with the neuropores

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Is there a communication between the mesoderm and the Neuroectoderm ?

Yes

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Anterior neuropore closes at day
Posterior neuropore closes at day

25
28

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Is the anterior pore fails to close or if the posterior pore fails to close what congenital malformations will rise

Ancephaly
Spina bifida

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what are the changes between day 25 and 28 (6)

1- inc in head size
2-umbilical cord formation
3-closure of neuropores
4- inc in somites number
5-Indentations for limbs
6- otic palcode gives rise to eyes and ears

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BMP and FGF are secreted from (endo-ecto-meso)?

Ectoderm

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Neural crest cells are what type of cells

Neuralectodermal

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When does the formation and migration of neural crest cells happen

During neural tube closure

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At the dorsal part cells begin to detach and migrate from neural tube and as they detach, they change their profile from epithelial to mesenchymal

they will give rise to structures that are associated to the CNS , ganglions

😊

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Mention the function of the following
-Developing superarenal gland
-Preaortic ganglion
-Enteric ganglion

-secretes cortisol from the kidneys
-Controls vasodilation vasorestriction
-GI tract To increase or decrease digestion

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Why do the neural crest cells detach and migrate

Because some parts of the nervous system are not dorsal.the neural tube and neural crest cells are dorsal, while other ganglions and nerves are all over the body. So immigration is needed

Why are BMPs and FGFs Are necessary for neural crest formation? Exam question

As we said, neural crest cells form ganglions, and ganglions all are all over the body not only dorsally where the neural tube is so ventralization genes are necessary

What is the significance behind transforming the profile of neural crest cells from epithelial to mesenchynal?

To have the ability to migrate

In the case of ancephaly what organ fails to form

Most of the brain

If the neural tube fails to close below the cervical region what might result

Spina bifida Most commonly and the lumbosacral region

The somatic mesoderm is also known as ___, And it surrounds the__ The splanchnic mesoderm is also known as ___, And it surrounds the__

Parietal, ectoderm Visceral, endoderm

When does the Paraxial mesoderm begins to be organized as segments, and what are the segments called

Beginning of the third week Somitomeres

Somitomeres formation proceeds

Cephalocaudally

Somitomeres are further organized into

Somites

By the end of the 5th week how many somites are formed

42-44

How many parts does a somite have

Scleratome myotome dermatome

Go to slide 16 and check the positions of the somites

Okay?

what TF is needed to develop muscle cell from the dorsomedial part of the somite? And what induces it? MYOD WNT BMP4 PAX3 NT3 SHH PAX1 NOGGIN MYF5

MYF5, WNT from dorsal///SHH from the ventral part

what TF is needed to develop skin cells cell from the middorsal part of the somite? And what induces it? MYOD WNT BMP4 PAX3 NT3 SHH PAX1 NOGGIN MYF5

PAX3 NF3 dorsal part

what TF is needed to develop muscle cell from the ventrolateral part of the somite? And what induces it? MYOD WNT BMP4 PAX3 NT3 SHH PAX1 NOGGIN MYF5

MYOD WNT from ectoderm , BMP4 from intermediate mesoderm

what TF is needed to develop bones from the scleratome part of the somite? And what induces it? MYOD WNT BMP4 PAX3 NT3 SHH PAX1 NOGGIN MYF5n

PAX1 SHH ventral , noggin notochord

Which part is incorporated with a developing fetus (endo-ecto-meso)

Endoderm, visceral

Reveal answer for a note!

The endoderm germ layer covers the ventral surface of the embryo and forms the roof of the yolk sac

What causes both the head and tail regions to move ventrally forming cranial and caudal body folds

Growth of brain vesicles Lengthening of the neural tube

The embryo lies within which cavity >

Amniotic cavity

When the umbilical region in the ventral region doesn’t close completely, it leaves

A connection between the yolk sac and the gut

At the cranial end, the foregut is separated from the ___ by ___

Stomodeum Oropharyngeal membrane

At the caudal region, the hind gut is separated from the ___ by

Exterior (amniotic cavity) Cloacal membrane

What remains in connection with the yolk sac?

Midgut

Maturation of tissues and organs and rapid growth takes place

Fetal period

Weight gain is striking during last__ months of gestation

Growth in length is conspicuous in

Fetal period, 3-5 months

During this period, Slowdown of head growth compared to rest of the body

Fetal

Face becomes more human-looking

3rd month

Eyes and ears move to the adult position

Third month

Upper limbs reach their relative length

3rd month

In the third month, only ___ limbs reach the relative length

Upper

Primary ossification centers (bone formation) present in skull during

3rd month

External genitalia develop - can be seen in ultrasound during

3rd month

Intestinal loops are withdrawn into the ___ during

Abdominal cavity third month

When and why will the pregnant mother start to feel some kicks

During the third month because of muscular activity

Muscular activity during

3rd month

The fetus is lined with fine lanugo hair, When and why

4-5 month To protect the skin

Why is the fetus reddish by the sixth week

Because of the development of blood vessels

Why does a fetus born at six months may not survive

Because the lung has not developed yet

Why does the fetus increases in weight in the last two months

In the last two months, the position of sub continuous tissue takes place which results in

What proteins differentiates the mesoderm into 3 segments

BMP4