Peds- abdomen embryology Flashcards
what 5 things are included in embryology?
- fertilization
- zygote
- blastula
- gastrula
- organogenesis
what is organogenesis?
cephalocaudal and lateral foldings lead to formation of primitive/primordial gut from endoderm
what are the 3 primary germ layers?
- endoderm (inner layer)
- mesoderm (middle layer)
- ectoderm (external layer)
3 primordial gut parts?
- foregut
- midgut
- hindgut
What forms the foregut? (9)
- pharynx
- oral cavity
- upper/lower respiratory system
- esophagus
- stomach
- duodenum
- liver
- bile ducts
- pancreas
during duodenal development what occurs?
- during duodenal development, the lumen becomes obliterated and recanalizes
- if this fails, duodenal atresia or stenosis occurs
- infants present with bile-stained vomiting
what does the midgut form?
- part of duodenum
- jejunum
- ileum
- cecum
- appendix
- part of transverse colon
when does physiological herniation occur?
9-11 weeks
what is physiological herniation?
- when does midgut return into abdomen?
- what are the last structures to return?
- what becomes fixed to posterior of andominal cavity?
- rapidly enlarging liver and kidneys cause a shortage of room
- midgut forms a loop and elongates into the umbilicus (week 9)
- midgut returns to abdo. by the 12th week (anticlockwise rotation)
- cecum and appendix are the last structures to return
- large bowel becomes fixed to the posterior of abdo. cavity
what does the hidgut form?
- left 3rd of transverse colon
- descending colon
- sigmoid
- rectum
- upper part of anal canal
What is the rectum separated from the urogenital organs by?
a septum
if there is abnomral seperation from rectum and urogenital organs what occurs?
- fistulas to the urethra, bladder, and vagina occur
When does the liver, GB, and bild duct system form?
4-6th week of fetal development
endodermal outgroth or hepatic diverticulum forms at what week?
4-6th week of fetal development
How does the endodermal outgrowth or hepatic dicerticulum form?
- caudal portion?
- cephalic portion?
- caudal portion differentiates into cystic duct and bile duct
- cephalic portion 2 buds begin forming the right and left hepatic lobes
cephalic portion of liver formation?
- The buds grow into columns that branch and form networks
- These eventually become the liver sinusoids.
- The columns of endodermal cells and the liver parenchyma grow into the surrounding mesoderm
- The mesoderm provides tissue for the portal tracts and the Glisson capsule
When do the liver lobes become different sizes?
- In the beginning both lobes are equal in size
- The liver begins developing blood cells
- By end of 6th wk right lobe becomes larger, left lobe undergoes some degeneration
- Liver fills most of the abdominal cavity
Liver, Gallbladder and Bile Duct System- oxygenated blood/ nutrients are delivered via?
- 2 branches?
- umbilical vein, which has two branches
- Intrahepatic part of umbilical vein joins left portal vein (ligamentum teres)
- Ductus venosus flows into IVC (ligamentum venosum)
Ligamentum venosum and teres can become recanalized as?
collaterals in portal hypertension
what is the spleen?
- intraperitoneal
- lymphatic organ
what does the spleen form from?
- mesenchymal cells
- mesodermal
How does the spleen develop?
cells differentiate to form the:
- splenic pulp
- supportive connective tissue
- capsule pulp
spleen- what does while pulp consist of?
- lymphatic tissue (lymphocytes and macrophanges)
spleen- what does red pulp consist of?
- vascular sinuses that are capable of storing morse than 300ml of blood
What does the pancreas develop from?
- ventral and dorsal pancreatic buds
- mainly derived from the dorsal pancreatic bud
What pancreatic bud appears first?
dorsal pancreatic bud
where does the ventral pancreatic bud develop?
near the entry of the bile duct to the duodenum
ventral bud forms?
dorsal bud forms?
ventral bud - uncinate process/head
dorsal bud- body/tail
what forms the main panc. duct of wirsung?
- ventral and dorsal buds fuse, the duct system fuses
Development of the renal tract?
- the development of the urinary and genital systems are intimately related
- The ducts from the urinary system go on to be incorporated into the genital system
- Occurs in 3rd week of fetal development
kidneys begin to form from?
- mesoderm
what three sets of excretory organs develop in an embryo in a cranial to caudal progression?
- pronephros
- medonephros
- metanephros
pronephros?
rudimentary non-functioning
mesonephros?
well developed and functions briefly
metanephros?
becomes permanent kidneys
what becomes the permanent kidney?
metanephros
Renal tract 4th week?
- pronephros
- mesonephros
The Pronephros:
-degenerates rapidly, leaving a duct to be used by the next kidney
The Mesonephros:
- forms caudad to the pronephros
- provides partial function while permanent kidneys continue to develop
- by the end of the embryonic period, the mesonephros → the mesonephric ducts/ Wolffian ducts (male genital structures), disappear in females
rental tract 5th week?
- metanephros
- nephrons
The Metanephros:
- appears as ureteric buds
- distal end forms the pelvis, calyces, collecting tubules
- proximal portion forms the ureters
Nephrons form from the mesoderm around the buds.
at first how does the permanent kidney lie?
- close to each other in the pelvis
- as abdomen grows the kidneys move cranially until they come in contact with the adrenal glands
What 2 parts do the adrenal glands consist of?
- medulla
- cortex
adrenal gland- medulla?
- developed from neural crest cells (sympathetic)
- Adrenal medullary pathology may appear along the sympathetic neurons at the celiac axis
Adrenal glands cortex?
- derived from gonadal mesoderm
- Ectopic adrenocortical tissue along the gonadal migration path
adrenal gland develop from?
- different embryonic tissues
- form 2 different anatomical and functional structures within one endocrine gland
