NM702 EXAM 3 QUESTIONS AND ANSWERS WITH COMPLETE SOLUTIONS VERIFIED

NM702 EXAM 3 QUESTIONS AND ANSWERS WITH COMPLETE

SOLUTIONS VERIFIED


What are the three processes that comprise implantation? -

(1) Loss of the zona pellucida ("hatching" of the blastocyst) 5 days after fertilization,

followed by rapid proliferation of the trophectoderm to form the trophoblast cell mass;

(2) Adherence of the blastocyst to the endometrial surface, which leads to the decidual

reaction;

(3) Erosion of the epithelium of the endometrial surface, with burrowing of the blastocyst

beneath the surface.

When is the ideal window for implantation of the blastocyst into the endometrium? -

The ideal window for synchronization between the uterus and blastocyst and thus

normal implantation is thought to occur around 8 days after ovulation

Describe what happens in the uterus to make it receptive to the blastocyst? -

•The endometrium prepares for implantation by the cyclic secretion of 17b-estradiol and

progesterone.

•Uterine receptivity is characterized by increased vascularity and edema of the

endometrium, increased secretory activity of the endometrial glands, decrease in the

polysaccharide matrix surface coating of the epithelial cells, and development of

pinopods (microprotrusions) on the epithelial surface.

When does the blastocyst adhere to the endometrium -

,• By 5 to 6 days after fertilization (7 to 9 days after ovulation), the blastocyst rests on

and adheres to the endometrium.

where does the blastocyst usually attach? -

The place of attachment is usually on the upper posterior wall of the uterus, near the

side where the ovary with the corpus luteum is located

What is its orientation when the blastocyst attaches -

The blastocyst orients itself so that the embryonic pole containing the embryo-forming

inner cell mass contacts the endometrial surface first.

Which layer of the blastocyst is the trophoblast, and what does the trophoblast develop

into? -

The trophoblast is the outer later and develops into the placenta

What are the two layers of the trophoblast? Which layer secrets hCG and what is the

function of that hCG? -

• the inner cytotrophoblast and the outer syncytiotrophoblast layer.

•The trophoblast, primarily the syncytiotrophoblast, produces hCG (which maintains the

corpus luteum during early pregnancy)

What is the result if the trophoblast invasion into the endometrium does not occur

effectively? -

•If trophoblast invasion is too extensive, placenta accreta can result; if invasion is too

little, the risk of miscarriage or placental abruption is increased.

What is the physiology behind implantation spotting (the scant bleeding that may occur

upon implantation)? -

,The syncytiotrophoblast is a thick multinuclear mass, without distinct cell boundaries,

that puts out fingerlike projections that invade the endometrial epithelium, engulfing

uterine cells. Slight bleeding may occur during this process, which may be mistaken for

a scanty, short menstrual period.

When is the process of implantation complete, and what is the condition of the

blastocyst at this point? -

•Implantation is complete by 10 days after fertilization. At this point, the blastocyst lies

beneath the endometrial surface and is covered by a blood clot and cellular debris. By

10 to 12 days, the endometrial epithelium has regenerated in this area.

What are the two layers of the endometrium and what does each layer contain? -

Endometrial lining has 2 layers - epithelial layer of mucus-secreting and ciliated cells.

Endometrium has 2 zones: top layer contains glands and blood vessels; deepest layer

is where secretory activity and regeneration after menstrual sloughing. Hormones after

fertilization lead to hypertrophy of the epithelium and stromal (deep) cells.

How does the blastocyst receive nutrition? -

•Under stimulation of progesterone and estrogen, the epithelium and stromal cells

become progressively hypertrophic and develop subnuclear vacuoles rich in glycogen

and lipids. Early nutrition of the blastocyst is from digestion of substances in endometrial

tissue and surrounding capillaries.

Describe the "decidual reaction"? -

•The endometrial changes during pregnancy are known as the decidual reaction, and

the altered endometrial lining is known as the decidua.

•The decidual reaction involves remodeling of the extracellular matrix with changes in

, collagen, proteoglycans, and glycoproteins.

•Decidualization also involves alterations in local immune cells and processes and

changes in maternal spiral arteries

What is a poor dicidual reaction associated with? -

•A poor decidual reaction is associated with placenta accreta and ectopic pregnancy. In

addition these pathways are altered in endometriosis leading to impaired implantation.

What is the relationship between the decidual reaction and the window of receptivity for

implantation? -

•As decidualization increases, the window of receptivity for implantation is closed.

What is the role of the decidua? -

•In addition to its role in early nutrition of the embryo, the decidua may protect the

endometrium and myometrium from uncontrolled invasion by the trophoblast cell mass.

•The decidua also acts as a physical barrier and—via production of cytokines that

promote trophoblast attachment, not invasion—to protect the endometrium during the

period when trophoblast cells migrate out of the placenta to the maternal spiral arteries

What is just above the area of trophoblast proliferation, initially covers the growing

embryo. -

Decidua Capsularis

What with development of the chorion, gradually regresses. -

Decidua Capsularis

What is the portion of the decidua on which the blastocyst rests, forms a soft, spongy

vascular bed, site of the future placenta, forms the maternal portion of the placenta and

the stratum in which separation of the placenta will occur at delivery -