Gastrulation

Question 1

Invagination

Answer 1

Folding of the surface epithelium of the blastula usually at the vegetal pole to form a central tube, archenteron

Question 2

Blastopore

Answer 2

Point of invagination

Question 3

Involution

Answer 3

Similar to invagination and also forms an archenteron that extends towards the animal pole from a blastopore

Question 4

Ingression

Answer 4

Migration of individual cells from surface epithelium into the interior of the embryo

Question 5

Primary mesenchyme cells

Answer 5

Apical surface of vegetal plate form bottle cells which ingress into blastocoel, remaining clustered at vegetal plate to form precursors of the mesoderm

Question 6

Cadherins

Answer 6

Ca2+ dependent adhesion molecules

Question 7

Convergent-extension

Answer 7

Cells become elongated perpendicular to axis of elongation and form actin and myosin rich lamellipodia at opposite poles. Lamellipodia used to exert traction on each other and drive cell intercalation narrowing invaginating tube and elongating towards animal pole

Question 8

Secondary mesenchyme cells

Answer 8

Complete elongation of archenteron. Form at invaginating tip of archenteron and produce filopodia

Question 9

Filopodia

Answer 9

Long cytoplasmic extensions that search for basal surface of animal pole§

Question 10

Trophoblast

Answer 10

Outer epithelium at 16-32 cell stage of holoblastic cleavage, forms chronic layers of placenta

Question 11

Inner cell mass

Answer 11

Small population of internal mesenchyme- like cells at 16 to 32 cell stage

Question 12

First step in development of mammalian ICM

Answer 12

Formation of hypoblast and epiblast

Question 13

Hybolast layer is adjacent to

Answer 13

Blastocoel

Question 14

Heuser’s membrane

Answer 14

Layer of exraembryonic endoderm deriving from hypoblast spreading around trophoblast lining the blastocoel

Question 15

Yolk sac

Answer 15

Enclosed cavity by Heuser’s membrane

Question 16

Meckel’s diverticulum

Answer 16

Small bulge in the small intenstine and is most frequent congenital malformation of digestive tract

Question 17

Amniotic membrane

Answer 17

Layer of flattened epithelial, extraembroynic ectoderm,cells lining amnion formed by epiblast

Question 18

Synctiotrophoblast

Answer 18

Tissue formed when trophobolast is in contact with endometrium. Highly invasive and penetrates uterine walls, secreting enzymes that digest the extracellular matrix which normally surrounds and connects cells.

Question 19

Cytotrophoblast

Answer 19

Trophoblast cells lining blastocoel in contact with ICM remaining a single layered cellular epithelium

Question 20

Lacunae

Answer 20

Cavities in the synctiotrophoblast filled with maternal blood from uterine capillaries

Question 21

HCG

Answer 21

Required to maintain progesterone production by the corpus luteum

Question 22

Buccopharyngeal membrane

Answer 22

Formed by epiblast layer at future rostral pole

Question 23

Cloacal membrane

Answer 23

Formed by hypoblast layer at future caudal pole

Question 24

Primitive streak

Answer 24

Ridge of cells at midlien of caudal half of epiblast layer on 14th day

Question 25

Node

Answer 25

Mould of cells at rostral end of primitive streak

Question 26

Somites

Answer 26

Paired blocks formed progressively along rostral-caudal axis by paraxial mesoderm.

Question 27

Anecephaly

Answer 27

Failure to close anterior neural tube causes brain degeneration and failure to form cranium

Question 28

Spina bifida

Answer 28

Failure to close posterior end leads to severe paralysis

Question 29

Pharyngeal arches

Answer 29

Cranial neural crest cells which differentiate as cartilage and bone migrate into ventral region of head

Question 30

Phylotypic stage

Answer 30

Where vertebrate embryos are most similar

Question 31

The ICM forms

Answer 31

tissues of fetus, amniotic membrane, yolk sac epithelium, vascalature of placenta and umbilical cord

Question 32

The amniotic membrane is formed from the

Answer 32

Epiblast layer

Question 33

The epiblast layers has ______ epithelium

Answer 33

Simple cuboidal

Question 34

Chronic somatomammotropin

Answer 34

Maintains placental growth

Question 35

Chronic thyrotropin

Answer 35

Regulates mothers metabolism

Question 36

Chronic corticotropin

Answer 36

Regulates growth of mammary glands

Question 37

Trophoblast blocks _______ by ______ antigen

Answer 37

Pregnancy termination by paternal antigen

Question 38

Buccopharyngeal form

Answer 38

mouth

Question 39

Cloacal

Answer 39

anus

Question 40

Nucleus pulposus is the only area where

Answer 40

notochord is retained in inter-vertebral discs

Question 41

Neural plate of ectoderm is formed at the

Answer 41

end of gastrulation

Question 42

Apical constriction and convergent-extension is needed for

Answer 42

neural tube closure

Question 43

Splachnic mesoderm is formed from

Answer 43

Embryonic folding

Question 44

Krox20 is necessary for transcription of

Answer 44

Rhomborents 3 + 5