H&n 4 Anterior Head Development

Front 1

Before the folding, cardiogenic region is

Back 1

cephalic to the cephalic end of the embryo

Front 2

Before folding, lateral plate mesoderm is

Back 2

split at the lateral edge of embryo

Front 3

Before folding, somatic mesoderm surrounds

Back 3

the amnion

Front 4

Before folding, Splanchnic mesoderm surrounds

Back 4

endoderm

Front 5

Lateral edges of splanchnic and somatic mesoderm pinch (direction)

Back 5

ventrally and medially

Front 6

Lateral edges of splanchnic and somatic mesoderm reduce

Back 6

left to right dimension of the connection btw developing gut tube and yolk sac

Front 7

Space btw Splanchnic and somatic mesoderm, results from splanchnic pinching in ahead of somatic

Back 7

intraembryonic coelum

Front 8

Cardiogenic region eventually becomes what to the cephalic end of the embryo?

Back 8

ventral to that end

Front 9

The cephalic end of the embryo first arcs

Back 9

90 degrees to point ventrally, then arcs another 90 to point toward caudal end

Front 10

The caudal end of the embryo first arcs

Back 10

90 degrees to point ventrally, then arcs another 90 to point toward cephalic end

Front 11

Connection btw developing gut tube and yolk sac does what in the cephalic 2 caudal direction?

Back 11

shortens

Front 12

The connection btw developing gut tube and yolk sac narrows where?

Back 12

in left to right dimension- due to lateral folding;

cephalic to caudal dimension- due to cephalocaudal folding

Front 13

What remains after the gut tube and yolk sac connection narrows?

Back 13

vitelline duct

Front 14

Cephalic end arching creates

Back 14

the head fold - a depression btw 2 bulges

What are the 2 bulges?

Front 15

Heart bulge located where?

Back 15

caudal to the head fold

Front 16

Frontonasal prominence located where?

Back 16

cephalic to the head fold; rostral/anterior to the pituitary fossa

Front 17

Frontonasal prominence contains

Back 17

abundant ectoderm - on exterior surface and in cephalic end of neural tube

hardly any mesoderm

Front 18

Swinging caudally from the deep end of the head fold are in sequence what?

Back 18

stomodeum - primitive mouth pit

buccopharyngeal membrane

primitive pharynx- connects to the developing gut tube

Front 19

Buccopharyngeal membrane dissolves when?

Back 19

Early in development (week 4)

Front 20

Buccopharyngeal membrane important only as border btw what?

Back 20

more superficial tissues with somatic sensation;

deeper tissue with visceral sensation

Front 21

Each pharyngeal arch is what shape?

Back 21

horseshoe shaped

Front 22

External surfaces of the pharyngeal arches is

Back 22

convex and symmetric across the anterior midline of the embryo; partially obscured by the heart bulge

Front 23

The internal surface of each pharyngeal arch is

Back 23

concave

Front 24

Each pharyngeal arch has all 3 germ layers where?

Back 24

Ectoderm - external surface of the arch

Endoderm - inner surface of the primitive pharynx and gut tube

Mesoderm - btw the ectoderm and endoderm

Front 25

Where are the furrows located?

Back 25

between the arches on both the external and internal surfaces of the embryo

Front 26

Grooves (clefts) are what?

Back 26

furrows on the external surface of the embryo

Front 27

Pouches are what?

Back 27

furrows on the internal surfaces

Front 28

Pharyngeal arches are derived from what?

Back 28

gills of fish, but pharyngeal arches have no openings created by groove/pouch contact

Front 29

How do fluids reach the pouch sides of the arches?

Back 29

passing through the stomodeum

Front 30

How many sources of mesoderm are in the arches and what are they?

Back 30

3; paraxial, somatic, and neural crest cells

Front 31

Paraxial mesoderm give rise to what?

Back 31

myotomes, sclerotomes, and dermatomes

Front 32

Somatic mesoderm reach the arches when?

Back 32

during lateral folding

Front 33

During development of the 1st pharyngeal arch, 4 prominences develop due to what?

Back 33

mainly the proliferation of the mesoderm

Front 34

During development of the 1st pharyngeal arch, the mandibular prominences travel how?

Back 34

start caudal and lateral to the head fold and grow toward the ventral midline; fuses with its counterpart to form a mandibular arch

Front 35

During development of the 1st pharyngeal arch, axillary prominences travel how?

Back 35

grow in a ventral and cephalic direction; does NOT form an arch

Front 36

During development of the 2nd through 6th arches, the prominences grow how?

Back 36

like the mandibular arch, toward the ventral midline;

develop in numerical order, with each additional arch smaller and more caudal than the one before

Front 37

During development of the 2nd through 6th arches, exception to the pattern is

Back 37

The 5th arch breaks down soon after forming