General embryology

Question 1

When do syncytiotrophoblasts form by?

Answer 1

1 week after conception - produce HCG to maintain the corpus luteum
Note: b-hCG is detectable in maternal serum ~8 days after fertilization and in the urine 14 days after fertilization

Question 2

neural development (neural plate –> neural fold)

Answer 2

day 18-21
Note: In the 3rd week of pregnancy called gastrulation, specialized cells on the dorsal side of the embryo begin to change shape and form the neural tube. When the neural tube does not close completely, an NTD develops.

Question 3

Annular pancreas (pancreas encircling descending duodenum) is caused by failure of what to properly migrate and fuse?

Answer 3

Ventral pancreatic bud fails to migrate and fuse with dorsal bud

Question 4

Dorsal pancreatic bud forms what? Ventral bud?

Answer 4

Dorsal - Majority of pancreas (body, tail, and most of head), accessory pancreatic duct
Ventral - uncinate process, inf/post head, major pancreatic duct
Failure to fuse –> pancreas divisum

Question 5

Foramen ovale adult remnant?

Answer 5

Fossa ovale

Question 6

Umbilical vein adult remnant?

Answer 6

Ligamentum teres

Question 7

Umbilical artery adult remnant?

Answer 7

Medial umbilical ligaments

Question 8

Ductus venosus adult remnant?

Answer 8

Ligamentum venosus

Question 9

Female in resp distress. XRay shows NG tube in L hemithorax, displacement of mediastinum to the R and absence of bowel gas in the abdomen. Embryologic event that caused this?

Answer 9

Incomplete formation of the pleuroperitoneal membrane
PLEUROPERITONEAL MEMBRANES fuse with the dorsal mesentery of the esophagus and with the dorsal part of the septum transversum to complete the partition between the thoracic and abdominopelvic cavities to form the primitive diaphragm.