"Microscopic Anatomy Female Reproductive II David W. Pruyne" 3/30

Question 1

What histological features distinguish a menstrual phase endometrium from a proliferative phase endometrium from a secretory phase endometrium?

Answer 1

Menstrual phase: Functional layer (including the surface epithelium) is absent, leaving the endometrium only ~ 0.5 mm thick.
• Bases of uterine glands are present in the basal layer, and are lined by secretory cells forming a simple columnar epithelium. In the basal layer, uterine glands are often parallel to the lumen surface.
• The stroma is densely-packed with cells (mostly fibroblasts).
Proliferative phase: The functional layer has regrown and the endometrium is now 2 – 3 mm thick. • The simple columnar surface epithelium has been restored.
• Uterine glands are long, straight and narrow through the functional layer.
• Stromal cells are spaced further apart in the functional layer than in the basal.
• Mitotic profiles can be found among fibroblasts and secretory cells.
Secretory phase: • The endometrium is now ~ 5 – 6 mm thick.
• Uterine glands are dilated and highly coiled, giving a cork-screw appearance. Their lumens contain secretory product.
• Stromal cells are spaced further apart in the functional layer than in the basal.
• Mitotic profiles are seldom found.
• Spiral arteries are prominent.

Late menstrual phase uterus: Surface epithelium is absent. Tubular glands
can be of various morphologies.
Proliferative phase uterus: Long, straight, tubular glands with narrow lumens. Simple columnar epithelium covers the surface. At high magnification, mitotic profiles are apparent.
Secretory phase uterus: Long, coiled, tubular glands with dilated lumens. Simple columnar epithelium covers the surface. At high magnification, secretory product is often apparent in the lumen.

Question 2

What structural feature of the functional layer leads to its shedding during the menstrual phase? Why is the basal layer not also shed?

Answer 2

Progesterone loss at the end of the menstrual cycle causes progesterone-sensitive spiral arteries to constrict and interrupt blood flow to the functional layer.
• Hypoxia and secondary damage trigger functional layer loss through menstrual flow. • Straight arteries that supply the basal layer are not affected.

Question 3

What features of the secretory endometrium make it a favorable environment for receiving and sustaining a developing embryo?

Answer 3

• Uterine gland secretions nourish the embryo until an embryo implants.
• The trophoblast cells produce human chorionic gonadotropin (hCG), to sustain the corpus luteum.
• The trophoblast forms the chorion, or embryonic portion of the placenta. Part of the endometrium forms the decidua basalis, or maternal portion of the placenta. Finger-like chorionic villi are invaded by fetal blood vessels, allowing exchange of nutrients, oxygen and wastes between fetal and maternal blood.

Question 4

What is endometriosis, and how does it occur?

Answer 4

Endometrial stromal and glandular cells colonize outside the uterus.
• Occurs when endometrial tissue sloughed during menses moves retrograde through the oviducts into the peritoneal cavity.
• Potential sites: ovaries, outer surfaces of the uterus or oviducts, broad ligament, colon, rectouterine pouch, rectal sheath.
• Explanted endometrial tissue remains hormone- sensitive, undergoing periods of growth followed by periods of tissue degradation and bleeding through the menstrual cycle.
• This can cause inflammation and pain, and formation of scar tissue, including adhesions between organs.

Question 5

What are leiomyomas?

Answer 5

Fibroids:
Benign tumors of smooth muscle.
• Appear in one out of four women.
• Grow in response to estrogen, and during pregnancy. • Generally asymptomatic.

Question 6

What histological features of the cervical glands would allow you to distinguish them from uterine glands in the endometrium?

Answer 6

Long, non-coiled, tubular glands that branch fairly frequently and have dilated lumens. Simple columnar epithelium covers the surface. Mucus-based secretory product is often apparent in the lumen.

• Cervical mucosa: stroma, simple columnar surface epithelium, and long, non- coiled, branched tubular glands with wide lumens. Cervical gland secretions are mucus-based. The cervical mucosa is not shed during the menstrual cycle.

Question 7

What are the sources of Nabothian cysts ad chocolate cysts?

Answer 7

Endometriosis: In the particular case where endometrial tissue infiltrates the ovary surface, blood can be trapped beneath the tunica albuginea, forming large chocolate cysts, so- called for the brown color of accumulated blood.

Non- pathogenic Nabothian cysts are a common result from gland occlusion of the cervix. Note: Nabothian cysts are commonly seen in the cervix, but cysts can also develop in the endometrium, and therefore are not reliable features for identifying the cervix.

Question 8

Describe the parenchyma and stroma of the inactive breast, the lactating breast and the breast during pregnancy.

Answer 8

Inactive breast ducts
• Intralobular stroma: abundant loose connective tissue.
• Interlobular stroma: dense connective tissue.
• Simple columnar epithelium of duct epithelial cells lines the ducts.

Pregnant breast: Parenchyma grows in response to hormones, while stroma decreases.
• Duct epithelial cells proliferate to form end buds, which are solid masses of epithelial cells at the duct ends. Mitotic profiles are apparent during first half of pregnancy.
• End buds hollow-out to form alveoli lined by secretory cells.
• Eosinophils, lymphocytes, and plasma cells (*) infiltrate the stroma.

Lactating breast: ** looks like thyroid gland
Lobules are nearly all parenchyma, with little visible stroma.
• Milk (or colostrum) is present in active alveoli (A) and ducts (D).

Question 9

Name three cell types of the breast that contribute to lactation, and describe their roles.

Answer 9

• Secretory cells lining the alveoli secrete protein and lipid components of milk. This is reflected by their basophilic cytoplasm, and a large, poorly-stained lipid droplet in the apical cytoplasm.
• Plasma cells in the stroma synthesize IgAs. These are transferred into the alveolar lumens by secretory cells.
• Myoepithelial cells contraction drives milk into the ducts.

Question 10

What is the medical importance of the terminal duct lobular unit?

Answer 10

Breast cancer Most commonly arises from the terminal duct lobular unit (TDLU) (lobule plus the interlobular duct that services it).

Question 11

Stroma of the endometrium has what type of collagen?

Answer 11

Type III

Stroma is made mostly of fibroblasts

Question 12

What kind of arteries supply the endometrium?

Answer 12

• Spiral arteries supply the functional layer, while small straight arteries supply the basal layer.

Question 13

What are vascular lacunae?

Answer 13

Thin-walled vascular lacunae in the functional layer provide a maternal blood supply to an embryo immediately after implantation.

Question 14

What happens to the endometrium during the proliferative phase?

Answer 14

• Estrogen, as a mitogen, triggers proliferation in the basal layer.
• Stromal fibroblasts multiply and produce extracellular material, generating a new functional layer of the endometrium.
• Secretory cells multiply, elongating the glands and restoring the surface epithelium. • Spiral arteries regrow into the functional layer.

Question 15

What happens to the endometrium during the secretory phase?

Answer 15

• Progesterone stimulates several changes:
• Uterine gland secretory cells undergo hypertrophy, causing coiling of the glands. • Uterine gland secretory cells release glycogen- and glycoprotein-rich product, dilating the gland lumens.
• Thin-walled vascular lacunae appear beneath the surface epithelium.

Question 16

Hot pink stain around glands in the secretory endometrium is highlighting what?

Answer 16

Glycogen

Question 17

What forms/becomes the chorion?

Answer 17

The trophoblast

Question 18

How are maternal and fetal blood separated?

Answer 18

Fetal capillaries (C) and sinusoids (S) in the smallest chorionic villi are separated form spaces containing maternal blood (MB) by only a thin wall of syncytiotrophoblasts

Question 19

What is the myometrium?

Answer 19

• Thickest portion of the uterine wall.
• Three indistinct layers of smooth muscle.
• Progesterone: inhibits smooth muscle contractions, increasing the probability of successful implantation during the secretory uterine phase.
• During pregnancy, the smooth muscle undergoes hyperplasia and hypertrophy, and synthesizes collagen fibers, increasing the size and strength of the uterine wall. The vasculature of the myometrium also increases. These changes reverse after pregnancy.

Question 20

What part of the uterus is continuous with the broad ligament?

Answer 20

Peri (epi) metrium

Simple squamous

Question 21

Where is the most common site of cervical cancer?

Answer 21

Cervical carcinomas arise from stratified squamous epithelium, most frequently at the transformation zone

Question 22

Describe the parts of the vagina, histologically.

Answer 22

• Vaginal mucosa: stratified, squamous, non-keratinized epithelium (E) overlying a highly cellular lamina propria (L). Papillae of the lamina propria reach into the epithelium. No glands. Lymphocytes and neutrophils frequently infiltrate the mucosa.
• Vaginal muscular layer (M): two indistinct sublayers: an inner layer of circularly- arranged smooth muscle fibers, and an outer layer of longitudinal fibers.
• Vaginal adventitia: elastic connective tissue forms a resilient outer sheath.

Question 23

What is a breast lobule?

Answer 23

Breast lobule (Lobule): composed of intralobular ducts (IlD), tubuloalveoli (Ta), and end buds (E), that are embedded in loose connective tissue, the intralobular stroma.
• Intralobular ducts drain into interlobular ducts (ID) as they exit the breast lobule.
• Terminal duct lobular unit: a breast lobule plus its associated interlobular duct.

Question 24

What are lactiferous ducts?

Answer 24

Lobules are separated by dense connective tissue (CT), the interlobular stroma.
• Interlobular ducts drain into lactiferous ducts (LD) and lactiferous sinuses (LS), which empty at the nipple.