The Uterus

Question 1

The uterus is a thick-walled pear-shaped organ that is derived from a structure known as

Answer 1

the female gubernaculum in the differentiated fetus.

Question 2

The gubernaculum is comprised of muscular fibers derived from

Answer 2

mesonephric and inguinal abdominal wall derivatives.

Question 3

The gubernaculum must fuse with the fetal mülerian ducts to allow or together with the mesonephric ducts to induce

Answer 3

Adequate uterine formation and development

Question 4

The uterus provides the site for

Answer 4

embryo implantation, fetal development and parturition

Question 5

To fulfill these functions the muscular layer (myometrium) and the mucosal layer (endometrium) are more complex than in

Answer 5

the vagina and oviduct.

Question 6

The entrance to the uterus is protected by ___________ and the exit from the uterus is composed of the __________.

Answer 6

the cervix and paired utero-tubal junctions that lead into the oviducts.

Question 7

The uterus is comprised of the following three layers:

Answer 7

Perimetrium, Myometrium, Endometrium

Question 8

Perimetrium

Answer 8

Epithelial tissue that covers the outside (exterior) of the uterus.

Question 9

Myometrium

Answer 9

The middle layer of the uterus that is primarily responsible for expulsion of the fetus during parturition.

Question 10

Most of the uterine tissue volume is

Answer 10

myometrium

Question 11

The myometrium smooth muscle fibers are arranged as interlacing bundles that run in horizontal, vertical, diagonal directions allowing for

Answer 11

the powerful contractions necessary during parturition.

Question 12

What hormone indirectly causes excitability of the myometrium contractions by sensitizing it to make it more responsive to external stimulation?

Answer 12

Estrogen

Question 13

What hormone makes the myometrium quiescent?

Answer 13

progesterone

Question 14

During the follicular phase of the menstrual cycle E concentrations are high and the uterus may exhibit random strong contractions.These menstrual cycle uterine contractions will also stimulate the pain innervation of the uterus leading

Answer 14

to the sensation of menstrual cramps.

Question 15

Under the influence of the estrogens of pregnancy the smooth muscle layer markedly

Answer 15

increases in size through both hypertrophy and hyperplasia.

Question 16

During pregnancy, menstrual cramps are rare due to the presence of concurrently

Answer 16

High concentrations of progesterone

Question 17

At parturition, decreasing levels of P and increasing levels of E causes

Answer 17

Forceful contractions of the myometrium to expel the fetus

Question 18

At parturition, decreasing levels of P and increasing levels of E causes forceful contractions of the myometrium to expel the fetus. These contractions also

Answer 18

Cut blood supply to the fetal placenta that precipitates the detachment from the uterus

Question 19

Endometrium

Answer 19

The innermost layer contains supportive broad highly cellular stromal and connective tissue containing many simple tubular glands (the lamina propria) covered by cuboidal to columnar epithelial tissue that forms the lining of the uterine lumen.

Question 20

The endometrium undergoes regular cyclic changes under the sequential influence of estrogen and progesterone during successive menstrual cycles in preparation for the potentially implanting embryo.

Answer 20

During the follicular (predominantly E) phase of the menstrual cycle the endometrium proliferates (proliferative phase). In the luteal phase influenced by P form and the endometrium thickens further (secretory phase).

Question 21

The endometrium consists structurally of the following two layers:

Answer 21

i. Stratum basalis
ii. Stratum functionalis

Question 22

Stratum basalis:

Answer 22

The basal layer that is adjacent to the myometrium and forms part of the lamina propria. The basalis is not as responsive as the other two layers to the ovarian steroids (E & P) and is not shed during menses.

Question 23

Stratum functionalis:

Answer 23

The functional layer that contains the glandular portion of the lamina propria and the epithelial tissue that lines the lumen.

Question 24

This “functional layer” thickens during each menstrual cycle under the influence of

Answer 24

E and P and is shed during menstruation

Question 25

The functionalis can be further subdivided into the:

Answer 25

1. Intermediary stratum spongiosum 2. luminal stratum compactum

Question 26

Intermediary stratum spongiosum layer

Answer 26

characterized by a stroma that has a spongy appearance

Question 27

Luminal stratum compactum

Answer 27

associated with a compacted stromal layer that is thinner than the other layers.

Question 28

The endometrium has a rich vascular supply that plays a central role in the

Answer 28

menstrual cycle

Question 29

The uterine artery has multiple branches that pass through the myometrium and immediately divide into two distinct types of arterial patterns:

Answer 29

straight arteries and spiral arteries.

Question 30

The straight arteries supply blood to

Answer 30

the basalis layer

Question 31

The spiral arteries are larger and thicker than the straight arteries and are

Answer 31

coiled as they enter the functionalis.

Question 32

As spiral arteries approach the surface of the endometrium they give off numerous side branches that

Answer 32

form an arterial plexus within the stratum functionalis.

Question 33

The growth of the spiral arteries is stimulated by

Answer 33

estrogen and progesterone.

Question 34

If pregnancy does not occur E and P levels drop at the end of the menstrual cycle causing

Answer 34

vasoconstriction of the spiral arteries.

Question 35

Restriction of blood flow to the endometrium is a precipitating event in the

Answer 35

shedding of the functionalis at the time of menses.

Question 36

Evidence suggests an __________ process mediated by __________ also plays a role bringing about the enzymatic autodigestion and degradation of the functionalis tissue and its capillary plexus.

Answer 36

1. apoptotic 2. cytokines