body folding embryo

Question 1

what does growth involve?

Answer 1

cell division &elaboration of cell products

Question 2

what does morphogenesis involve?

Answer 2

development of shape, size, and other features of a particular organ or part or the whole body

Question 3

what is morphogenesis controlled by?

Answer 3

gene expression & regulation in an orderly sequence

Question 4

what is Differentiation ?

Answer 4

cells are organized in a precise pattern of tissues & organs that are capable of performing specialized functions

Question 5

what is the first step in body folding?

Answer 5

Primordium of the intraembryonic coelom (embryonic body cavity) appears

Isolated coelomic spaces Coalesce to form the intraembryonic coelom

Question 6

intraembryonic coelom divides lateral mesoderm into what?

Answer 6

Somatic (parietal) layer of lateral mesoderm

Splanchnic (visceral) layer of lateral mesoderm

Question 7

what is the somatopleure?

Answer 7

somatic mesoderm& overlying embryonic ectoderm form body wall

Question 8

what is the splanchnopleure?

Answer 8

splanchnic mesoderm & underlying embryonic endoderm form embryonic gut

Question 9

how does folding occur?

Answer 9

cranial & caudal ends, & sides occurs simultaneously

Question 10

why is folding significant? whats important about the lateral edges

Answer 10

Folding is significant for creating correct body form

Embryo increases in length, but lateral edges cannot keep pace

Question 11

when does embryo elongate?how?

Answer 11

cranially & caudally (4thweek/day 22)

Question 12

overgrowth of neural folds over oropharyngeal membrane causes what?

Answer 12

moves septum transversum, primordial heart, pericardial coelom, & oropharyngeal membrane to ventral surface

Question 13

Endoderm forms what when it is incorporated into foregut?

Answer 13

primordium of pharynx, esophagus, & lower respiratory system

Question 14

after head folding has occured, what position is embryo in?

Answer 14

Pericardial cavity is ventral

• Pericardioperitonealcanals run dorsally on each side of the foregut
• Intraembryonic & extraembryonic coeloms are in communication

Question 15

folding of caudal end of embryo is due to what?

Answer 15

growth of the distal neural tube

Question 16

tail folding causes what change in position?

Answer 16

caudal eminence(tail region) projects over thecloacal membrane (future anus)

primitive streak lies caudal to cloacal membrane

Allantois is partially incorporated

Connecting stalk attached to ventral surface

Question 17

terminal hindgut forms what?

Answer 17

cloaca

Question 18

what produces the R/L lateral folds

Answer 18

Rapid growth of SC & somites

Extend ventrally toward the midline

Creates a cylindrical embryo

Question 19

what happens to abdominal wall as a result of lateral folding?

Answer 19

incorporates endoderm to form themidgut

Question 20

how is omphaloentericduct formed due to lateral folding?

Answer 20

Connection btwnumbilical vesicle & midgutis reduced

Question 21

as a result of lateral folding what happens to amnion?

Answer 21

Amniotic cavity expands, obliterates most of extraembryonic coelom

Amnion forms epithelial covering of umbilical cord

Question 22

Gastroschisis,what happens?

Answer 22

Protrusion of viscera; site of the abdominal defect is to the right of the umbilical cord

bowel is uncovered and floating in the amniotic fluid

lateral folding deficiency

Question 23

Congenital epigastric hernia, what happens?

Answer 23

Midline bulge of abdominal wall located between the xiphoid process & umbilicus

Bowel is not exposed to the amniotic fluid

Question 24

intraembryonic coelom will be divided into what?

Answer 24

pericardial cavity, pleural cavities, & peritoneal cavity

Question 25

Parietal wall is derived from what?

Answer 25

somatic mesoderm

Question 26

visceral wall is derived from what?

Answer 26

splanchnic mesoderm

Question 27

pericardial cavity does what during head folding?

Answer 27

relocated ventrally, anterior to the foregut opens into pericardioperitonealcanals (2), located dorsal to the foregut now cranial to septum transversum

Question 28

where are Pericardioperitonealcanals after headfolding?

Answer 28

dorsal to septum transversum

Question 29

dorsal mesentery does what after head folding?

Answer 29

suspends Caudal foregut, midgut, & hindgut in the peritoneal cavity

Question 30

partitions in pericardioperitonealcanal are called what?

Answer 30

Pleuropericardial folds (cranial) Pleuroperitonealfolds (caudal)

Question 31

Pericardial cavity and pleural cavities separated how?

Answer 31

pleuropericardial Membranes fuse with mesenchyme ventral to esophagus (7thweek)

Question 32

Bronchial buds grow into what to split mesenchyme? what does it split into?

Answer 32

pericardioperitonealcanals Outer layer → thoracic wall inner layer → fibrous pericardium

Question 33

Pleuroperitoneal Membranes are formed how?

Answer 33

Pleuroperitoneal folds enlarge, project into pericardioperitoneal canals Form as developing lungs & pleural cavities expand/invade the body wall

Question 34

how are Pleuroperitoneal Membranes closed?

Answer 34

Fuse with dorsal mesentery of esophagus & septum transversum in week 6 Myoblasts migrateinto the pleuroperitonealmembranes & completes closure process

Question 35

Septum transversum forms what ? how?

Answer 35

fuses with dorsal mesentery of the esophagus & pleuroperitonealmembranes central tendon of diaphragm

Question 36

Pleuroperitonealmembranes form what?

Answer 36

primordial diaphragm

Question 37

dorsal mesentery forms what?

Answer 37

median portion of diaphragm

Question 38

Myoblasts form what?

Answer 38

cruraof the diaphragm

Question 39

how is innervation of diaphragm formed? how is the phrenic nerve related to this?

Answer 39

Pleuropericardial membranes contain cardinal veins AND myoblasts migrating through diaphragm Myoblasts pull ventral rami (C3-C5) with them. Phrenic subsequently lies on fibrous pericardium

Question 40

what is a congenital diaphragmatic hernia?

Answer 40

Viscera bulge into pleural cavity Lung maturation may be delayed; polyhydramnios may be present diaphragm doesnt close ! Left side typically impacted (80%) Can be corrected at birth