Lab2

Question 1

Fertilization

Answer 1

Process that initiates development; ovum and spermatozoon fuse to form an embryo.

Question 2

Gray crescent

Answer 2

Crescent-shaped area located between the pigmented animal hemisphere and unpigmented vegetal hemisphere.

Question 3

Zygote

Answer 3

Single cell embryo.

Question 4

Cleavage

Answer 4

Phase of development in which embryo’s cells rapidly undergo mitosis with little or no cell growth.

Question 5

Holoblastic cleavage

Answer 5

Type of cleavage in which two seperate daughter cells form.

Question 6

Radial cleavage

Answer 6

Cleavage plane is perpendicular or parallel to the previous one.

Question 7

Rotational cleavage

Answer 7

During second cleavage, one blastomere divides meridionally, and the other equatorially.

Question 8

Morula

Answer 8

a solid ball of cells resulting from division of a fertilized ovum, and from which a blastula is formed.

Question 9

Blastula

Answer 9

an embryo at the end of the cleavage stage when it is a sphere of cells surrounding a cavity, the blastocoel.

Question 10

Blastomere

Answer 10

An embryonic cell of an early embryo formed during the cleavage stage.

Question 11

Micromere

Answer 11

Small cells; in sea urchins they are located in the vegetal pole; in amphibians they are the cells of the animal hemisphere.

Question 12

Macromere

Answer 12

4 large blastomeres of the vegetal hemispheres.

Question 13

Blastocoel

Answer 13

A cavity within the embryo at the blastula or blastocyst stage.

Question 14

Gastrulation(gastrula)

Answer 14

Phase of development during which the 3 embryonic germ layers form. An embryo undergoing this phase is called a gastrula.

Question 15

Primary germ layers

Answer 15

ectoderm(outermost layer), mesoderm(middle layer), endoderm(innermost layer)

Question 16

Invagination

Answer 16

Infolding or a buckling inward of a sheet of cells during gastrulation.

Question 17

Involution

Answer 17

Inward migration of an expanding outer sheet of cells during gastrulation so that it spreads over the basal surface of the remaining external cells.

Question 18

Epiboly

Answer 18

Expansion of an outer sheet of cells during gastrulation to cover the embryo’s surface.

Question 19

Blastopore

Answer 19

The opening of the archenteron which in deuterostomes becomes the anus.

Question 20

Dorsal blastopore lip

Answer 20

A lip-like structure over which the cells involute during gastrulation. It is the amphibian organizer. (Spemann organizer)

Question 21

Bottle cells

Answer 21

The first cells to migrate inwards at the blastopre during amphibian gastrulation.

Question 22

Marginal zone

Answer 22

Area surrounding the equator of the amphibian embryo where the micromeres and macromeres meet.

Question 23

Archenteron

Answer 23

The embryonic gut. Also called gasrocoel.

Question 24

Yolk plug

Answer 24

24.A small patch of endoderm cells that protrudes from the amphibian blastopore.

Question 25

Chordamesoderm

Answer 25

Mesoderm that generates the notochord.

Question 26

Neurulation

Answer 26

Process by which the neural tube forms. Embryo undergoing this is neurula.

Question 27

Neural plate

Answer 27

Thickened ectoderm which is the earliest rudiment of the central nervous system.

Question 28

Neural fold

Answer 28

The paired, raised lateral edges of the neural plate to form the neural tube during neurulation.

Question 29

Neural groove

Answer 29

The depression in the neural plate located between the raised neural folds.

Question 30

Neural tube

Answer 30

A dorsal tube of neural ectoderm cells that run along anterior-posterier axis and give rises to the central nervous system.

Question 31

Neurocoel

Answer 31

The lumen of the neural tube.

Question 32

Neural ectoderm

Answer 32

Embryonic ectoderm that becomes the neral plate, neural folds, and neural tube.

Question 33

Skin ectoderm

Answer 33

Ectoderm that differentiates into the epidermis of the skin.

Question 34

Neural crest cells

Answer 34

Group of ectoderm cells that migrate to various areas of the embryo to become several structures.

Question 35

Forebrain

Answer 35

The rostral region of the embryonic brain.

Question 36

Prosencephalon

Answer 36

The most rostral primary region of the neural tube that gives rise to the forebrain.

Question 37

Telecephalon

Answer 37

Rostralmost brain vesicle located cranial to the diencephalon.

Question 38

Diencephalon

Answer 38

Second brain vesicle located between the telencephalon and mesencephalon.

Question 39

Midbrain(mesencephalon)

Answer 39

Middle region of the embryonic brain.

Question 40

Hindbrain(rhombencephalon)

Answer 40

The caudal region of the embryonic brain that gives rise to the metencephalon and mylencephalon.

Question 41

Notochord

Answer 41

A longitudinal, rod-like structure that runs the length of the dorsal embryonic axis between the digestive and neural tube.

Question 42

Paraxial(segmental plate) mesoderm

Answer 42

Mesoderm that lies to the left and right sides of the neural tube that gives rise to the somites.

Question 43

Somites

Answer 43

Paired blocks of paraxial mesoderm located ventrolateral to the neural tube.

Question 44

Mesenchyme

Answer 44

Loosely scattered cells mostly of mesoderm origin.

Question 45

Foregut

Answer 45

Cranial region of the embryonic gut.

Question 46

Midgut

Answer 46

Middle region of the embryonic gut.

Question 47

Hindgut

Answer 47

The caudal region of the embryonic brain.