Vert. Anatomy 3

Question 1

Amniotes

Answer 1

Vertebrates that lay eggs on land and their descendants

Question 2

Macrolecithal

Answer 2

extremely large amount of yolk that remains outside of the body; can develop musculoskeleton & respiratory system before hatching
-reptiles, birds, monotremes

Question 3

Secondarily microlecithal

Answer 3

egg that reverts to the microlecithal condition from ancestors that were macrolecithal

Question 4

Eutheria

Answer 4

“placental” mammals

Question 5

Metatheria

Answer 5

marsupial mammals

Question 6

Cleavage

Answer 6

a period of rapid cell division during which the cell cycles are abbreaviated; G1 & G2 are essentially skipped

Question 7

Maternal effect genes

Answer 7

mRNA from the mother used to synthesize proteins during cleavage

Question 8

Blastula

Answer 8

Result of cleavage in microlecithal and mesolecithal embryos consisting of a hollow ball of cells surrounding a cavity

Question 9

Blastocoele

Answer 9

cavity of a blasula

Question 10

Macromeres

Answer 10

Develop from the vegetal hemisphere of mesolecithal embryos

Question 11

Micromeres

Answer 11

Develop from the animal hemisphere of mesolecithal embryos

Question 12

Cleavage of macrolecithal embryos

Answer 12

only occurs at the animal pole

Question 13

Blastoderm

Answer 13

single layer of cells covering the blastocoele

Question 14

Blastodisc

Answer 14

the thin, flat disc of tissue covering the blastocoele; as seen from above

Question 15

Posterior Marginal Zone (PMZ)

Answer 15

the edge of the blastoderm, along the rim of the blastocoele; homologous to the gray crescent

Question 16

Chorion

Answer 16

a thin membrane that covers the entire outer surface of the yolk

Question 17

Extraembryonic ectoderm

Answer 17

The chorion and other ectoderm

Question 18

Extraembryonic endoderm

Answer 18

the inner surface of the blastoderm, continuous endoderm of the gut

Question 19

Hypoblast

Answer 19

A sheet of cells from the posterior marginal zone that spreads across the center of the blastocoele, dividing it into upper and lower cavities.

Question 20

Subgerminal cavity

Answer 20

cavity below the hypoblast; will form the gut and a couple of extraembryonic cavities; precursor to the endoderm

Question 21

Epiblast

Answer 21

the upper layer of tissue overlying the subgerminal cavity formed by the original blastoderm

Question 22

bilaminar stage

Answer 22

two-layered body stage of development of macrolecithal amniotes

Question 23

Syncytiotrophoblast

Answer 23

the outer layer of the trophoblast; a continuous mass of cytoplasm formed by cells fusing together (in therian mammals)

Question 24

Morula

Answer 24

undifferentiated clump of cells formed during the early rounds of mitosis

Question 25

Blastocyst

Answer 25

In therian mammals, the stage in which a cavity forms within a morula
Unlike a blastula, the cells surrounding the cavity do not form the body of the embryo

Question 26

Inner cell mass

Answer 26

cluster of cells located within the cavity that the body will develop from

Question 27

Trophoblast

Answer 27

the layer of cells surrounding the blastocyst, involved in implantation and formation of the placenta

Question 28

Syncytiotrophoblast

Answer 28

outer layer of the trophoblast
-produces enzymes that digest the wall of the uterus at whatever location the blastocyst comes into contact with it, causing implantation

Question 29

Endometrium

Answer 29

the surface of the uterine wall