Embryology 1&2

Question 1

Specialized process of cell division that occurs only in the germ line

Answer 1

Meiosis

Question 2

A diploid 2N cell replicates its DNA (becoming diploid, 4N) and undergoes a single division to yield 2 diploid 2N daughter cells

Answer 2

Mitosis

Question 3

Day 0, fertilization, once a haploid sperm fuses with the haploid egg the egg is then called a ________.

Answer 3

Zygote

Question 4

Zygote initiates a rapid series of mitotic cell divisions called _________.

Answer 4

cleavage

Question 5

Day 1 (24 hours) The cells increase in number but the zygote does not increase in size, these daughter cells are called ___________.

Answer 5

Blastomeres

Question 6

Day 3 (72 hours) what happens?

Answer 6

Compaction: The cells become adhered to one another by tight junctions by Compaction.

Question 7

Day 4 (96 hours) what happens?

Answer 7

At 3 days there are 6-12 cells and by day 4 it consists of 16-32. The embryo is called Morula at this stage.

Question 8

What are the centrally placed blastomeres called?

Answer 8

Embryoblast

Question 9

What are the blastomeres at the periphery called?

Answer 9

Trophoblast

Question 10

The trophoblast is the primary source of the fetal component of the ______.

Answer 10

Placenta

Question 11

Day 5 (120 hours) what happens?

Answer 11

Blastocyst formation

Question 12

Morula reaches the uterus between 3 and 4 days of development. The blastocyst becomes tightly adhered to the uterine lining called ___________.

Answer 12

Implantation

Question 13

Cells of the uterus respond to its presence and to progestrone secreted by the corpus luteum by forming secretory cells called _________.

Answer 13

Decidual cells, response called the decidual reaction

Question 14

Before implantation occurs the embyroblast differentiate into 2 epithelial layers and by day 8 they are distinct and are called what?

Answer 14

Epiblast (columnar cells around outside)

Hypoblast (primitive endoderm)

Question 15

True/False: Epiblast is ventral

Answer 15

False, Epiblast is dorsal

Question 16

True/False: Hypoblast is Ventral

Answer 16

True

Question 17

By 9 days what has happened?

Answer 17

The embryo is completely implanted in the uterine endometrium and then the amniotic cavity is formed.

Question 18

Amniotic cavity is enclosed by what?

Answer 18

epiblast

Question 19

Migrating hypoblast cells merge to form a second cavity called the _______________.

Answer 19

Primary yolk sac

Question 20

Hypoblast cells start to migrate to form what?

Answer 20

heuser’s membrane

Question 21

Days 10 and 11, extraembryonic mesoderm spontaneously splits and forms a crescent shaped cavity called what?

Answer 21

Chorionic cavity

Question 22

On days 12 and 13 a second wave of migrating hypoblast cells produces a new membrane that wants to divide itself, (kind of like meiosis) the primary yolk sac goes and disappears… This new membrane is called what?

Answer 22

Definitive yolk sac stays

Question 23

What yolk sac dissapates into nothing

Answer 23

Primary yolk sac

Question 24

The dorsal amnion and ventral yolk sac (definitive yolk sac) together is called what?

Answer 24

embryonic disc

Question 25

The dorsal amnion and ventral yolk sac (definitive yolk sac) is suspended in the chorionic cavity by a thick ________________.

Answer 25

connecting stalk

Question 26

At the end of week 2 is the embryo slowly dividing or quickly dividing?

Answer 26

Quickly dividing (exponential growth)