Fertilization and Implantation (M1B1)

Question 1

Contact between sperm and corona radiata cells will trigger the…………. of the sperm and releasing of…………… that allows sperm to move easily to the……………

Answer 1

acrosomal reaction, hyaluronidase, zona pellucida

Question 2

Binding of specific sperm proteins with ZP3 and ZP4 receptors will
activate the……………… on the acrosomal membrane to degrade
the zona pellucida locally.

Answer 2

protease acrosin

Question 3

The first sperm penetrating the zona pellucida fuses with the oocyte
plasmalemma and triggers the?

Answer 3

cortical reaction

This reaction converting the zona pellucida to the impenetrable perivitelline barrier to block polyspermy

Question 4

what is Tubal ligation?

Answer 4

common surgical type of contraception (prevention of pregnancy)

Question 5

what is Salpingitis?

Answer 5

inflammation of mucosa of fallopian tube uterine tube by infectious agents ascend from the lower genital tract

Question 6

what is Ectopic (tubal) pregnancy?

Answer 6

implantation inside the mucosa of

fallopian tube due to blockage of oocyte or embryo transport to the uterus.

Question 7

The zygote undergoes mitotic cleavages (divisions without cell growth) as it is moved toward the uterus forming morula with its cells called?

Answer 7

blastomeres

(About 5 days after fertilization the embryo reaches the uterine cavity,
by which time blastomeres have moved to form a central cavity in the morula and the embryo enters the blastocyst stage of development)

Question 8

blastomeres then arrange themselves as a peripheral layer called the……………. around the cavity, while a few cells just inside this layer make up the embryoblast or inner cell mass

Answer 8

trophoblast

Question 9

Cells of the embryoblast
rearrange around two new
cavities which are?

Answer 9

the amnion and the yolk sac

yolk sac and amnion form extra embryonic structures

Question 10

trophoblast will differentiates into?

Answer 10

■ The cytotrophoblast

■The syncytiotrophoblast

Question 11

what’s The cytotrophoblast?

Answer 11

a layer of mitotically active cells immediately around the amnion and yolk sac

Question 12

what’s The syncytiotrophoblast?

Answer 12

more superficial, nonmitotic mass of

multinucleated cytoplasm which invades the surrounding stroma

Question 13

The endometrial stroma undergoes histologic changes as its fibroblasts
become enlarged, polygonal, more active in protein synthesis, and are
now called?

Answer 13

decidual cells

Question 14

The whole endometrium is now called the decidua and includes?

Answer 14

■The decidua basalis between the 
implanted embryo and the myometrium.
■The decidua capsularis, the region 
between the embryo and the uterine 
lumen.
■The decidua parietalis, on the side of the 
uterus away from the embryo

Question 15

the site of exchange for nutrients, wastes, O2, and CO2 between the mother and the fetus is the?

Answer 15

placenta

Question 16

placenta contains tissues from both individuals which are?

Answer 16

a) The embryonic part is the chorion, derived from the trophoblast
b) The maternal part is from the decidua basalis.

Question 17

Chorionic villi of the developing placenta go through three stages which are?

Answer 17

■Primary villi appear 2 days after implantation as simple cords of
proliferating cytotrophoblast cells covered by syncytiotrophoblast extend into lacunae containing maternal blood.

■ Secondary villi begin to form on about the 15th day of embryonic development as the primary villi are invaded by extraembryonic mesenchyme.

■Tertiary villi develop within a few more days as mesenchyme in the secondary villi differentiates to form capillary loops continuous with the embryonic circulatory system

Question 18

The chorionic villi provide the surface area for metabolite exchange of
gases, nutrients, and wastes occurs between fetal blood in the
capillaries of villi and maternal blood that the villi bathing through it.

Answer 18

…

Question 19

The placental barrier is formed of?

Answer 19

1-Continuous endothelium of the
fetal capillary and its basal lamina

2- A layer of cytotrophoblasts and
its adjacent basal lamina

3- A layer of syncytiotrophoblasts
exposed to maternal blood.

Question 20

what is Placenta previa?

Answer 20

complication of pregnancy caused by faulty placental implantation into the uterine wall (close to the cervix or covering the cervical os) It leads to severe third trimester vaginal bleeding. It occurs in one in 200 pregnancies. Treatment depends on the severity but may include delivery by cesarean section.

Question 21

what is placenta accreta?

Answer 21

potentially life-threatening condition to the mother due to partial or complete absence of the decidua basalis results in placental adherence directly to the myometrium. It may require cesarean section followed by peripartum hysterectomy.