A&PII Lab 18: Embryonic Development

Question 1

Fertilization

Answer 1

successful union between a spermatocyte and oocyte

Question 2

Embryonic development

Answer 2

1st series of changes during prenatal development follow a series of cell divisions beginning with the 1st division and continuing for about 8 weeks

Question 3

Zygote

Answer 3

fertilized egg

Question 4

Cleavage

Answer 4

process of the zygote dividing by mitosis

Question 5

Morula

Answer 5

small of ball of cells (“little mulberry”); what the zygote is referred to as by the time it reaches the uterus (~3 days)

Question 6

Differentiation

Answer 6

cell division and change; includes the movement of fluid into the intercellular spaces of the morula, which gradually enlarges the space and separates the cells into 2 portions

Question 7

Trophoblast

Answer 7

outer layer of cells of the differentiated morula; later contributes to the placenta

Question 8

Inner cell mass

Answer 8

inner layer of cells of the differentiated morula; later becomes the embryo

Question 9

Embryo

Answer 9

“a swelling”; develops from the inner cell mass

Question 10

Blastocyst cavity

Answer 10

the intercellular spaces join to form 1 large cavity; AKA blastocele

Question 11

Blastocyst

Answer 11

once the intercellular spaces have joined to form 1 large cavity, the morula has become this cell

Question 12

Implantation

Answer 12

when the trophoblast contacts the inner wall of the uterus (endometrium), this process begins

Question 13

Germ layers

Answer 13

the cells on 1 side of the disc (ventral side) forms these layers; early cells that will eventually differentiate into the tissues and organs of the body

Question 14

Endoderm

Answer 14

1st layer formed from germ cells

Question 15

Ectoderm

Answer 15

2nd germ layer; from the dorsal side of the disc

Question 16

Mesoderm

Answer 16

middle germ layer; forms after the ectoderm

Question 17

Amniotic cavity

Answer 17

as small spaces begin to appear between the embryo and the trophoblast, this cavity begins to form

Question 18

Chorion

Answer 18

trophoblast differentiates to form this “membrane” in the 3rd week of implantation; membrane later associated with the fetus

Question 19

Placenta

Answer 19

the chorion will eventually form the embryonic portion of this “flat cake”

Question 20

Amnion

Answer 20

2nd membrane begins developing during the 3rd week; “little membrane of the fetus”; expands the fluid-filled amniotic cavity until it envelops the embryo

Question 21

Yolk sac

Answer 21

during the latter part of this developmental period, this 3rd membrane arises from the endoderm to form this cavity

Question 22

Primitive streak

Answer 22

thickening of the ectoderm layer along the midline of the embryo; gives rise to the 3rd germ layer (mesoderm) by folding inward (invaginates)

Question 23

Gastrulation

Answer 23

process of the primitive streak folding inward to form the mesoderm

Question 24

Gastrula

Answer 24

what the embryo is called during gastrulation; “little stomach”

Question 25

Notochord

Answer 25

during gastrulation, this rod-like structure begins to form as an outgrowth of mesodermal cells from the primitive streak

Question 26

Neural tube

Answer 26

once the notochord has formed, portions of the ectoderm invaginate to form this structure immediately dorsal to it; eventually gives rise to the CNS

Question 27

Neurulation

Answer 27

process of ectodermal growth

Question 28

Neurula

Answer 28

what the embryo is called during neurulation

Question 29

Foregut

Answer 29

head cavity of an embryo

Question 30

Hindgut

Answer 30

tail cavity of an embryo

Question 31

Midgut

Answer 31

part of the embryo formed earlier by the endoderm; develops further to become the GI tract

Question 32

Allantois

Answer 32

yolk sac + ____ = umbilical cord

Question 33

Umbilical cord

Answer 33

formed from the yolk sac and the allantois (membrane)

Question 34

Amniotic fluid

Answer 34

fluid within the saclike amnion that bathes the embryo until birth

Question 35

Organogenesis

Answer 35

process of development of the major organs of the body during the 1st 8 weeks of life