Lecture 4: Histology of the Female Reproductive System

Question 1

What is the general structure of the ovaries?

Answer 1

• Covered by a single layer of cuboidal mesothelial cells continuous with the mesovarium (germinal epithelium)
• A layer of CT (Tunica Albuginea) around the organ

ZONES:
• an outer cortex containing follicles in stages of development
• Central medulla with blood vessels and nerves in a dense CT stroma (supporting tissue)

Question 2

What starts follicle development?

Answer 2

FSH

Question 3

Normally ___ oocyte will be release at ovulation while other undergo atresia

Answer 3

One

Question 4

What are the features of the following follicles:

1. Primary follicle
2. Secondary follicle (how does it form?)
3. Mature (Graafian) follicle

Answer 4

• 45um
• Contains a central, immature ovum (primary oocyte) surrounded by a layer of cuboidal follicular epithelial cells called granulosa cells
• The stroma cells nearest the follicle form a layer (theca interna) and produce oestrogen
• Around the theca interna is a layer of CT cells, the theca externa
• A clear non-cellular glycoprotein layer (the zona pellucida) surrounds the oocyte

2. Secondary Follicle (Antral):

• Follicular epithelium of 5-12 primary follicles proliferates to form a multilayered capsule of follicular cells around the oocyte – the remainder degenerate (atresia)
• As this layer grows to 8-12 layers of granulosa cells, a small fluid-filled space (antrum) develops
• At maturity, (125-150 μm), the oocyte is embedded in a mound of granulosa cells at the edge of the antrum (cumulus oophorous). Attached to the zona pellucida, the innermost layer of granulosa is called the corona radiata. On ovulation, these cells (corona radiata) travel with the oocyte.

3. Mature (Graafian) Follicle:

• 10-14 days or longer is required for the primordial follicle to reach maturity as a mature or Graafian follicle about 1 cm in diameter.
• The oocyte remains connected to the layer of follicle cells that lines the antral cavity and underlies the basement membrane of the follicle (membrane granulosa).

Question 5

What two cells make up the corpus luteum?

Answer 5

Granulosa lutein cells (from granulosa cells)

Theca lutean cells (from theca interna cells)

Question 6

How long does the corpus luteum persist?

Answer 6

2 weeks without fertilization

11-12 with fertilization

Question 7

What are some of the features of the oviduct?

Answer 7

• A folded mucosa (mucous membrane) with ciliated simple columnar that beat toward the uterus and non-ciliated peg cells that are nutritive cells (secrete a fluid rich in nutrients)
• The lamina propria (layer outside epithelium) that has CT cells, blood vessels and leukocytes.
• The muscularis externa (muscular layer outside LP) has inner circular and outer longitudinal smooth muscle
• The serosa is a thin layer of CT covered by mesothelium (peritoneum)

Question 8

What are some of the features of the uterus?

Answer 8

• An outer layer, the peritoneum (serosa) – single layer of mesothelium resting on a layer of CT, containing blood and lymph vessels, nerves and sympathetic ganglia.
• middle, smooth muscular layer, the myometrium. Also contains stromal and vascular tissue.
• inner, glandular mucosa, the endometrium, which lines the uterine cavity.

Question 9

What is the structure of the endometrium?

Answer 9

simple columnar epithelium with or without cilia, a wide LP with mucosal glands, and the endometrial stroma. It is split into the stratum basalis (basal 1/3) and stratum functionalis (luminal 2/3).

Question 10

What are the key components of the uterine blood supply?

Answer 10

-Short, straight arteries that nourish the basal layer
-Spiral (helicine) branches that supply the functional layer.
Note: On menstruation, the spiral arteries constrict to shut off the blood flow.

Question 11

What are the phases of the menstrual cycle and when do they occur?

Answer 11

Proliferative stage (follicular phase):
Day 5 to day 14. Under estrogen, regeneration of the endometrium occurs, and epithelial cells are low columnar but gradually increase in height. At first, the glands are short, but as the mucosa thickens they increase in length.

Secretory (luteal phase)
Begins after ovulation on day 14 and continues until day 26. Major changes occur in the stratum functionalis; the basalis remains unchanged. The endometrium thickens, and the glands dilate, coil, and fill with glycogen and mucus. The coiled arteries increase in length.
These changes occur due to progesterone made in the corpus luteum.

Premenstrual or ischemic stage
At day 27. The coiled arteries begin to constrict due to reduced progesterone and oestrogen. The uterine glands cease to secrete, the endometrium thins due to water loss, and the st. functionalis become ischaemic.

Menstrual phase
Starts by a release of contraction of the coiled, resulting in a rush of blood into the previously closed arterioles. Weakened ischaemic walls of these vessels rupture, flooding the stroma with blood, separating the epithelium. The detached epithelium, uncoagulated blood, glandular secretions, and degenerating endometrial cells are shed into the uterine cavity.