Bilaminar Embryo

Question 1

The secondary oocyte is surrounded by

Answer 1

Zona pellucida and Corona radiata

Question 2

A think transparent gelatinous layer of protein and polysaccharides

Answer 2

Zona Pellucida

Question 3

Several layers of ovarian follicle

Answer 3

Corona radiata

Question 4

Sperm must penetrate what in order for fertilization to occur

Answer 4

Zona pellucida and Corona radiata

Question 5

What is capacitation

Answer 5

function changes that sperm undergo in the female reproductive tract that enable them to fertilize a secondary oocyte

Question 6

Capacitation increases what

Answer 6

sperm motility

Question 7

What is the acrosome and what is its function

Answer 7

modified lysosome that releases enzymes (hyaluronidase) (across) to help the sperm penetrate the corona radiate and zone pellucida

Question 8

What are the steps in fertilization

Answer 8

1. Sperm penetrates the egg, 2. Fusion of plasma membranes of sperm and oocyte, 3. Formation of male pronucleus, 4. Completion of second meiotic division of oocyte and formation of female pronucleus, 5. Fusion of pronuclei to form a zygote (diploid).

Question 9

How does the egg prevent polyspermy?

Answer 9

When a sperm enters the egg, there is a cortical reaction where the oocyte membrane becomes impenetrable to other sperm. There is also a zoo reaction where the zona pellucid alters its structure to prevent other sperm from binding and penetrating.

Question 10

What happens during the formation of the male nucleus?

Answer 10

The tail and mitochondria of sperm degrade because sperm are only needed for genetic material.

Question 11

All the mitochondria in the embryo comes from

Answer 11

The mother

Question 12

After fertilization the zygote undergoes a series of mitotic cell divisions known as _ as it migrates to the _

Answer 12

cleavage; uterus

Question 13

About 3 days after fertilization (12-32 cell stage) the embryo is termed a

Answer 13

morula (mulberry)

Question 14

The morula consists of a solid ball of cells with an

Answer 14

inner and outer cell mass

Question 15

The inner cell mass will become the _ and the outer cell mass will become the _

Answer 15

embryo; placenta

Question 16

The morula will enter the uterus by

Answer 16

day 4

Question 17

Fluid from the uterus penetrates the zone pellucid into the morula and forms a

Answer 17

hollow cavity transforming the morula into a blastocyst

Question 18

The fluid filled cavity of the blastocyst separates the blastomeres of the inner and outer cell mass into the

Answer 18

Trophoblast (outer cell mass) and the embryo blast (inner cell mass)

Question 19

The trophoblast is the

Answer 19

thin, outer layer that will make hCG which is the basis for pregnancy testing

Question 20

The embryo blast is

Answer 20

a group of centrally located blastomeres

Question 21

about 2 days after entering the uterus the blastocyst will

Answer 21

shed its zone pellucida in what is known as hatching, which allows the blastocyst to increase in size

Question 22

At the end of week 1, the blastocyst will attach to the

Answer 22

uterine endometrium at its embryonic pole and the trophoblast will invade the uterine wall

Question 23

What is an abnormal blastocyst

Answer 23

Most won’t produce any sign of pregnancy because trophoblast is defective and can’t produce enough hCG to maintain corpus luteum.

Question 24

What are Hydatidiform moles

Answer 24

Trophoblast develops and forms placental membranes will little or no embryonic tissue present. These moles contain “grape-like” vesicles and secrete high levels of hCG that may produce benign or malignant tumors. These end as spontaneous abortion or miscarriage.

Question 25

What is In Vitro fertilization?

Answer 25

Mature oocytes from stimulated ovaries are retrieved transvaginally with sonographic guidance. Sperm and ova are combined in vitro to force fertilization. If this is successful, viable embryos are transferred into the endometrial cavity.

Question 26

What is intracytoplasmic sperm injection?

Answer 26

Applicable to male factor infertility. The corona radiate is enzymatically digested and a single sperm is injected through the zone pellucid and oocyte cell membrane.

Question 27

The trophoblast will differentiate into what 2 layers?

Answer 27

Cytotrophoblast (inner layer of mono nucleated cells with mitotic capacity) and synctiotrophoblast (outer multinucleated zone that invades the uterine endometrium to implant the blastocyst; process hCG)

Question 28

Implantation is completed by

Answer 28

the end of week 2

Question 29

Site of implantation is marked temporarily by

Answer 29

a fibrin plug

Question 30

What is an abnormal implantation in the uterus?

Answer 30

Placenta previa- the blastocyst may implant close to the internal os of the cervix. The placenta may cover the internal os that results in painless vaginal bleeding in the late stages of pregnancy.

Question 31

What is an abnormal implantation outside the uterus?

Answer 31

Ectopic pregnancy give signs and symptoms of pregnancy with abdominal pain and tenderness.

Question 32

Where do ectopic pregnancies typically occur?

Answer 32

95% occur in the uterine tube but may also implant in the abdominal cavity in either the rectouterine punch or pouch of douglas

Question 33

The embryo blast will differentiate into which 2 layers?

Answer 33

The dorsal epiblast and the ventral hypoblast (transition structure that doesn’t form anything in the adult)

Question 34

Within the epiblast, clefts develop to form

Answer 34

the amniotic cavity and the amnion

Question 35

hypoblasts migrate and line the inner surface of the cytotrophoblast which forms the

Answer 35

exocoelomic membrane (or Heuser’s membrane)

Question 36

The exocoelomic membrane surrounds a space known as the

Answer 36

primitive or primary yolk sac (primary umbilical vesicle)

Question 37

What proliferates to fill the space between the cytotrophoblast and either the amnion or primitive yolk sac?

Answer 37

Extraembryonic mesoderm

Question 38

Cavities form within the extra embryonic mesoderm to form the

Answer 38

chorionic cavity (extraembryonic coelom)

Question 39

The chorionic cavity is surrounded by the

Answer 39

chorionic membrane

Question 40

The chorionic membrane is formed by the

Answer 40

extra embryonic mesoderm, cytotrophoblast, and the synctiotrophoblast.

Question 41

The extra embryonic mesoderm at the embryonic pole does not cavitate but instead forms

Answer 41

the connecting stalk which will become the future umbilical cord.

Question 42

The hypoblast produces cells that migrate along the inner surface of the primitive yolk sac to form

Answer 42

the definitive or secondary yolk sac/umbilical vesicle

Question 43

During formation of the definitive yolk sac, large portions of the primitive yolk sac are pinched off as

Answer 43

exocoelomic cysts in the chorionic cavity