L4 Flashcards by Asma 1

What is the structure that is implanted in the uterus

Blastocyst

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The bilaminar a germ disk is composed of

ICM that is differentiated into epiblast and hypoblast

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Fertilization occurs in___ while implantation is in___

The ampulla of the uterine tubes
The body of the uterus

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Cuboidal cells

Hypoblast

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Describe the cytotrophoblast

Inner layer of mononucleated cells

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Describe syncytiotrophoblast

Outer layer multinucleated zone without distinct cell boundaries

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Describe the hypoblast

Cuboidal cells adjacent to the blastocyst cavity

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Describe epiblast

Columnar cells adjacent to the amniotic cavity

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How is the Amnioblast formed

Embryoblast pulls away from the trophoblast forming a hollow Amniotic Cavity. Epiblast cells adjacent to the cytotrophoblast are called amnioblasts

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-secretes hCG

syncytiotrophoblast

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The extraembryonic mesoderm splits into 2 layers

Somatic splanchnic

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Extraembryonic mesoderm is formed from

Hypoblast

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What are the events of the second week of development

• The trophoblast differentiates into 2 layers
• The embryoblast forms 2 layers
• The extraembryonic mesoderm splits into 2 layers
• Two cavities form
• bilaminar disk

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Mention the events of the third week of development

Formation of the primitive streak
Appearance of primitive node
Migration of the epiblast cells toward the primitive streak
Formation of the 3 germ layers
Trilaminar disk

GASTRULATION GASTRULATION GASTRULATION

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The primitive node know it appears at the__- region

Cephalic end of the primitive streak

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The endoderm and mesoderm form from the

MIGRATION of the epiblast

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The ectoderm is formed from the_

REMAINING cells of the epiblast

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Signals a lot of transcription factors to indicate how gastrulation will occur

Primitive node

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Where is the primitive streak located

Caudomedial

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Indicates early signs of gastrulation

Primitive streak

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Interpret: all the body develops from epiblast

All the body develops from the MIGRATING epiblasts because they form the three germ layers

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Gives rise to the umbilical cord

Extraembryonic mesoderm from hypoblast

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Gives rise to the placenta

Syn. Trophoblast

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Will give rise to the notochord

Prenotochordal cells

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What is the job of the notochord

Established by the axis signaling molecules It was eventually disintegrate and the remnants will be in the vertebral disc

What is the function of cavities

Nourish the embryo

Where does the primitive node it appears

Cephalic end OF THE PRIMITIVE STREAK

The primitive streak appears on the ___ what is the primitive node __

Caudal end cephalic end

Organizes the migration of epiblast sense to form three germ layers

Primitive node

Ensures which transcription factors or genes will be expressed at which time

Primitive node

Which cells give rise to the notochord

Mesoderm

How do the notochord forms from the mesoderm

They attached to the endoderm forming a notochord plate then they detach from it

What are the two types of mesoderm

Intraembryonic extraembryonic

The intraembryonic mesoderm differentiates into

Paraxial lateral intermediate

Gives rise to somites

Mesoderm > intraembryonic > paraxial

Development is(direction)

Cephalocaudal Left to right Ventral to dorsal

Which side is established first R or L?

Left

Establishment of the body axes is in which week

2 and 3

Which genes regulate head development

HESX1 LIM1 OTX2

What is the location of the cells that regulate head development

Anterior, cranial and, AVE(endoderm)

OTX2 LIM1 AND HESX1 results in (2)

Anteroposterior axis Head formation

what occurs during gastrulation

Ventralization and dorsalization

What genes are responsible for ventralization

BMP4 FGF

BMP4 FGF are secreted through

Bilaminar disk

BMP4 FGF result in

Ventralization of mesoderm—> intermediate and lateral

Which gene transcription factor is responsible for dorsalization

Goosecoid

Goosecoid is expressed in

Node

Goosecoid results in

Regulate chordin expression + noggin + follistatin = inhibits the activity of BMP4 = dorsalize: mesoderm —> notochord Paraxial mesoderm —> head

Brachyury T gene results in

Inhibits BMP4 = dorsalize Mesoderm —> notochord Paraxial —> caudal

Ventralization is related to what types of mesoderm

Lateral intermediate

Dorsalization is related to what types of mesoderm

Paraxial —> head in goosecoid —> caudal BT gene

Which GTF regulates caudal genesis

BT gene

Which GTF regulates crainal genesis

HESX1 LIM1 OTX2 GOOSECOIDS // PARAXIAL —> CRAINAL

Which GTF regulates dorsal genesis

BT gene Goosecoids

Which GTF regulates ventral genesis

BMP4 FGH

FGF8 results in

Establish the nodal protein

Nodal proteins is a part of which superfamily

TGF-B

Nodal protein accumulates on the

Left side

What induces nodal, lefty1 and lefty 2 expression

FGF8 under the influence of 5HT And Brachyury T gene

Regulates PITX2

Nodal and lefty 2

PITX2 results in

Inc left side expression

on what side are Lefty 1 and 2

1– ventral, left side of the neural plate 2- lateral plate mesoderm

SHH results in

Mid line barrier Inc left side genes on the right

Are expressed in the NODE

Goosecoids FGF8 Nodal Chordin Follistatin Noggin

Expressed in the notochord

SHH BT gene

Epiblast cells adjacent to the cytotrophoblast are called

amnioblasts

As the neural plate starts to form, neurotransmitter serotonin (5HT) increases in concentration on the left side why?

Because MAO metabolizes 5HT on the right

Expression of the transcription factor Snailresults in

regulate downstream genes important for establishing right-sidedness

establish right-sidedness

Snail

The Extraembryonic mesoderm splits into two layers that are located between

Cytotrophoblast and exocoelomic membrane

Dorsalizing the mesoderm is required for the development of

Notochord BT gene : meso —> notocord Goosecoid: meso —> notocord

Which protein is required for mesoderm to Differentiate into three segments

BMP4

What guides migration of epiblast from the primitive pit

TGF, nodal

Provides cellular supply for the formation of three germ layers

Epiblast

Causes mesoderm to differentiate into an embryo

FGF8

From where do the epiblast sells migrate to form the Notochordal process

Primitive node

Insufficient development of which embryonic structure leads to caudal dysgenesis

Mesoderm

Which abnormality is associated with old age

Neural tube defects

Gastrulation is initiated by

primitive streak