Folding Of Embryo

Question 1

At the end of the —— week,
intraembryonic mesoderm differentiates into:

Answer 1

At the end of the 3rd week,
intraembryonic mesoderm differentiates into:
1.Paraxial mesoderm,
2.Intermediate mesoderm
3.Lateral plate mesoderm

Question 2

The ——- mesoderm gives rise to somitomeres and somites which play a major role in the formation of the skull and vertebrae
•——- mesoderm: contributes to the urogenital system
•———-mesoderm: formation of body cavity

Answer 2

he paraxial mesoderm gives rise to somitomeres and somites which play a major role in the formation of the skull and vertebrae
•Intermediate mesoderm: contributes to the urogenital system
•Lateral plate mesoderm: formation of body cavity

Question 3

•The lateral plate mesoderm splits into two to form:

Answer 3

Splanchnic mesoderm
•Somatic mesoderm

Question 4

——— lateral plate mesoderm becomes continuous with the extraembryonic splanchnic mesoderm around the yolk sac.
•——- lateral plate mesoderm becomes continuous with extraembryonic somatic mesoderm around the amniotic cavity

Answer 4

Splanchnic mesoderm becomes continuous with the extraembryonic splanchnic mesoderm around the yolk sac.
•Somatic mesoderm becomes continuous with extraembryonic somatic mesoderm around the amniotic cavity

Question 5

FOLDING OF THE EMBRYO
•Converts a flat trilaminar embryonic disc into a —— embryo
•Folding occurs simultaneously in ——- and ——— planes of the embryo
•Rate of growth in —- axis of the embryo overtakes rates at the —- of the embryo (—- fold)

Answer 5

FOLDING OF THE EMBRYO
•Converts a flat trilaminar embryonic disc into a cylindrical embryo
•Folding occurs simultaneously in transverse and longitudinal planes of the embryo
•Rate of growth in long axis of the embryo overtakes rates at the sides of the embryo (lateral fold)

Question 6

As the brain develops, the forebrain grows cranially beyond the ——- membrane, hence overhanging the developing heart
•Consequently, the primordial heart and oropharyngeal membrane moves unto the —— surface of the embryo

Answer 6

As the brain develops, the forebrain grows cranially beyond the oropharyngeal membrane, hence overhanging the developing heart
•Consequently, the primordial heart and oropharyngeal membrane moves unto the ventral surface of the embryo

Question 7

Head folding:
•During folding, the part of the endoderm that becomes incorporated (“trapped cranially into the fold”) into the embryo (lying between the brain and heart) forms the ——

Answer 7

ead folding:
•During folding, the part of the endoderm that becomes incorporated (“trapped cranially into the fold”) into the embryo (lying between the brain and heart) forms the foregut

Question 8

Tail folding:
•In the tail region, a part of the embryo projects over the —— membrane, such that a part of the endoderm becomes incorporated into the embryo- this forms the ——

Answer 8

ail folding:
•In the tail region, a part of the embryo projects over the cloacal membrane, such that a part of the endoderm becomes incorporated into the embryo- this forms the hindgut

Question 9

The portion of the endoderm between foregut and hindgut forms- ——-

Answer 9

The portion of the endoderm between foregut and hindgut forms- midgut

Question 10

Midgut communicates with the yolk sac at the yolk stalk which narrows to become- ——-

Answer 10

Midgut communicates with the yolk sac at the yolk stalk which narrows to become- vitelline (omphalomesenteric) duct

Question 11

Midgut communicates with the yolk sac at the ——which narrows to become- vitelline (omphalomesenteric) duct

Answer 11

Midgut communicates with the yolk sac at the yolk stalk which narrows to become- vitelline (omphalomesenteric) duct

Question 12

At its cephalic end, the foregut is bound by an ectodermal-endodermal membrane- ——- membrane
•Hindgut is terminated temporarily by a similar membrane- ——— membrane

Answer 12

At its cephalic end, the foregut is bound by an ectodermal-endodermal membrane- oropharyngeal membrane
•Hindgut is terminated temporarily by a similar membrane- cloacal membrane

Question 13

In the — week, the buccopharyngeal membrane ruptures, establishing an open connection between the ——and the ——

Answer 13

In the 4th week, the buccopharyngeal membrane ruptures, establishing an open connection between the oral cavity and the primitive gut

Question 14

In the 4th week, the ——- membrane ruptures, establishing an open connection between the oral cavity and the primitive gut

Answer 14

In the 4th week, the buccopharyngeal membrane ruptures, establishing an open connection between the oral cavity and the primitive gut

Question 15

The hindgut also terminates temporarily at an ectodermal-endodermal membrane- the ——- membrane, which breaks down in the —— week to create the opening for the —-.

Answer 15

The hindgut also terminates temporarily at an ectodermal-endodermal membrane- the cloacal membrane, which breaks down in the 7th week to create the opening for the anus.

Question 16

Lateral folding:
•During the —- week, the sides of the embryo begin to grow down forming how many lateral body walls folds
•These folds consist of the —- (somatic) layer of the lateral plate mesoderm and overlying ectoderm- ——-

Answer 16

Lateral folding:
•During the 4th week, the sides of the embryo begin to grow down forming 2 lateral body walls folds
•These folds consist of the parietal (somatic) layer of the lateral plate mesoderm and overlying ectoderm- somatopleure

Question 17

Lateral folding:
As these folds progress, the endodermal layer also folds —— and closes to form the ——.
•By the end of the —— week, the lateral body wall folds meet in the midline and fuse to close the ———.
•Failure of fusion leads to ——-

Answer 17

As these folds progress, the endodermal layer also folds ventrally and closes to form the gut tube.
•By the end of the 4th week, the lateral body wall folds meet in the midline and fuse to close the ventral body wall.
•Failure of fusion leads to ventral wall defects