Twinning & Fetal EPO

Question 1

_________ twins are formed when two different sperm fertilize two different secondary oocytes

Answer 1

Dizygotic

“Dizygotic is Different”

Question 2

_________ twins are formed when one sperm fertilizes one secondary oocyte, but instead of single blastocyst forming a single fetus, the inner cell mass splits into two

Answer 2

Monozygotic

Question 3

Monozygotic twins MOST COMMONLY develop a ______ placenta and chorion

Answer 3

Single

“Monochorionic, Diamniotic”

Question 4

Monozygotic twins MOST COMMONLY develop _____ amniotic sac(s)

Answer 4

Separate
“Monochorionic, Diamniotic”

The later the cleavage, the more likely that the twins will share amnion (“monochorionic, monoamniotic”) – if the cleavage is too late = conjoined twins

Question 5

Erythropoeisis begins in the ___ week of development

Answer 5

3

Question 6

EPO 3-8 weeks

Answer 6

Yolk Sac

“Young Liver Synthesizes The Blood”

Embryonic hemoglobin - delta2alpha2

Question 7

EPO 6-30 weeks

Answer 7

Liver

“Young Liver Synthesizes The Blood”

Fetal hemoglobin - gamma2alpha2

Question 8

EPO 9-28 weeks

Answer 8

Spleen and Thymus

“Young Liver Synthesizes The Blood”

Question 9

EPO 28 weeks onward

Answer 9

Bone Marrow

“Young Liver Synthesizes The Blood”

Adult hemoglobin - alpha2beta2