Embryology

Question 1

ICM produces this layer that has amitotic nuclei

Answer 1

Syncytiotrophoblast

Question 2

Trophoblastic cells that do not become part of syncytiotrophoblast become…

Answer 2

Cytotrophoblast

Question 3

Bilaminar germ disc

Answer 3

Epiblast and hypoblast

Question 4

Decidua reaction

Answer 4

Glandular secretions cause endometrium surrounding embryo to become edematous with glycogen and lipids

Question 5

ICM laminates into….

Answer 5

Amnion, epiblast, hypoblast

Question 6

Amnion

Answer 6

Membrane that forms along interior of cytotrophoblast

Question 7

Epiblast

Answer 7

Sheet of columnar cells from which entire fetus develops

Question 8

Amniotic cavity

Answer 8

Fluid filled cavity between amnion and epiblast into which fetus will grow

Question 9

Hypoblast

Answer 9

Between epiblast and blastocoel; produces yolk sac

Question 10

Extraembryonic endoderm

Answer 10

Hypoblast spreads along cytotrophoblast to create this membrane of flattened cells

Question 11

Yolk sac

Answer 11

Extraembryonic endoderm and space it surrounds

Question 12

Extraembryonic mesoderm

Answer 12

Forms between cytotrophoblast and extraembryonic endoderm; derived from extraembyronic endoderm

Question 13

Chorionic cavity

Answer 13

Extraembryonic lacunae that expand and coalesce into this layer within the extraembryonic mesoderm

Question 14

Splanchnic extraembryonic mesoderm

Answer 14

Surrounds yolk sac

Question 15

Somatic extraembryonic mesoderm

Answer 15

Lines cytotrophoblast

Question 16

Chorion

Answer 16

Extraembryonic mesoderm, cytotrophoblast, and syncytiotrophoblast

Question 17

Connecting stalk

Answer 17

Projection of extraembryonic mesoderm that attaches to amnion, germ disc, and secondary yolk sac; develops into umbilical cord

Question 18

Hensen’s node

Answer 18

Secretes GFs that induce tissue differentiation and embryogenic patterning

Question 19

Primitive streak begins…elongates….then….

Answer 19

At caudal end around day 15….toward cranial end until day 18 (about 2/3 the length of the germ disc)…regresses, disappearing by end of week 4

Question 20

Gastrulation

Answer 20

First mass movement of embryonic cells that compartmentalizes the embryo into endoderm, mesoderm, and ectoderm

Question 21

Endoderm

Answer 21

Forms gut and endothelial lining of numerous organs

Question 22

Mesoderm

Answer 22

Forms everything between epidermis and endothelium

Question 23

Ectoderm

Answer 23

Forms NS and epidermis

Question 24

Sacrococcygeal teratomas

Answer 24

Primitive streak fails to regress completely

Question 25

Caudal dysgenesis

Answer 25

Primitive streak regresses prematurely causing insufficient mesoderm in caudal region; anywhere from clubbed foot to sirenomelia

Question 26

Embryos develop from….to….

Answer 26

Cranial to caudal end

Question 27

Notochord derived from….

Answer 27

Hensen’s node; mesodermal

Question 28

Sclerotomes

Answer 28

Produce vertebrae by differentiating into cartilage and bone

Question 29

Myotomes

Answer 29

Differentiate into the muscles

Question 30

Dermatomes

Answer 30

Produce underlying dermis of skin

Question 31

Notochordal process

Answer 31

Epiblast cells invaginate and extend in the cranial direction to form this hollow tube

Question 32

Notochordal plate

Answer 32

Formed when notochordal process fuses with endoderm and opens ventrally, flatenning

Question 33

Prechordal plate

Answer 33

Region with adherent hypoblast and epiblast cells that block further progression of the plate; at this point the primitive streak regresses