Embrology Weeks 3-5 and clinical correlates Flashcards
Gastrulation
Formation of the primitive node and streak at the caudal end of the epiblast.
Trilaminar germ disc
Occurs right after primitive streak formation and is formed via hypoblast cells migrating thought the streak.
Makes the endo, excto and mesoderm
Endoderm
Formed to replace the hypoblast cell layer and becomes the ventral layer of the trilaminar disc
Mesoderm
Mesenchymal cells that dont form endoderm form mesoderm in the middle of the trilaminar disc
Ectoderm
Formed from epiblast cells that dont become mesenchymal cells via migration. Is the dorsal layer of the trilaminar disc.
Primordial germ cells
Originate from the epiblast and are the precursors for gametes
Situs solitus
Normal left-right asymmetry
Situs inversus
180 degree flip of normal right-left symmetry
Situs ambiguous
Partial 180 degree flipped organs in left-right asymmetry
Neurolation
Signals from the notochord causes ectoderm to thicken and from the neural plate.
Two parts of the neural plate
Neural groove: forms along the midline of the neural plate
Neural folds: sides of neural plates that form the neural crest.
Neural tube
Forms when the lateral edges of the folds come together. Gives rise to the CNS cells
Spinal bifida
Incomplete formation of the neural tube.
Neural crest cells
Detached cells migrate and give rise to PNS system, medula of the adrenal gland, melanocytes and facial bones
Surface ectoderm forms what?
Epidermis of skin, appendages and nasal cavities. Also the anus cavity.
Paraxial mesoderm forms what?
Cranial paraxial mesoderm: skeletal muscles, most cranium bones
Somatic paraxial mesoderm: produces dermatomes, myotome and sclerotomes.
Intermediate mesoderm forms what?
Tissues of the urogential system and the cortex ofthe adrenal gland.
Lateral plate mesoderm has what layers and produces what?
Splanchnic visceral mesoderm: smooth muscles, CT of the viscera and visceral linings of the thoracic organs. Also forms all heart layers and blood/lymph vessels
Somatic parietal mesoderm: serious epithelial layers of the thoracic region and fibrous pericardium
Endoderm forms what?
Forms with the gut tube (which will form the Digestive system organs).
Produces epithelial lining of the GI tract, bladder and urethra and the trachea/bronchi of the lungs.
Sarcococcygeal teratoma
Primitive streak does not disappear and causes tumors to form
- usually doesn’t kill fetus and can be safely excised
Hydatiform moles
Degenerating chorionic villi from fetus death causes moles in the mother.
- can evolve into chriocarcinomas and give the mother cancer.
Congenital diaphragmatic hernia (CDH)
Posterolateral defect in the formation of the diaphragm causes herniation of the intestines and stomach.
- this is caused by chromosal abnormalities and gene mutations to GATA6.
- usually compresses one lung and can cause pulmonary hypoplasia.
Diaphragmatic eventration
Defective diaphragm musculature caused by failure of migration into the plueroperitoneal membrane diaphragm to balloon into the thoracic cavity
- creates diaphragmatic pouch
Retro sternal herniations
Caused by intestinal herniation into the pericardial sac through the sternocostal hiatus
