Female Reproductive System I: The Ovaries Flashcards Preview

Unit 7 Histology > Female Reproductive System I: The Ovaries > Flashcards

Flashcards in Female Reproductive System I: The Ovaries Deck (20)
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1
Q

List the 4 layers of the ovaries and briefly describe them

A

1) Germinal epithelium
- highly regenerative
- modified mesothelium
- simple cuboidal epithelium

2) Tunica albuginea
- dense, irregular CT
- rich in collagen & contains fibroblasts

3) Cortex
- follicles
- highly cellular CT stroma
- low vascularity except around highly developed follicles and in glandular tissue

4) Medulla
- loose CT
- contains blood and lymphatic vessels and nerves that enter the ovary hilus

2
Q

what are primary oocytes? What do they originate from?

A

Primordial germ cells differentiate into oogonia, which will proliferate and enter meiosis, arresting at prophase 1 becoming known as primary oocytes

3
Q

T/F: Oocyte and follicle formation occur only during fetal development

A

True

4
Q

Stromal cells around the primary oocyte reorganize to form?

A

follicular epithelium

5
Q

What are the 4 follicles we can need to identify and what are some characteristics associated with them?

A

1) Primordial follicle
- smallest
- first follicle stage
- central primary oocyte surrounded by follicular epithelium (simple squamous -low metabolic activity)

2) Unilaminar primary follicle
- follicular cells become cuboidal in shape (higher metabolic activity)
- as follicles grow, they move deeper into cortex

3) Multilaminar primary follicle
- follicular cells become stratified, cuboidal epithelium (granulosa)
- zona pellucida (thick, acellular glycorpotein) surrounds primary oocyte (aid in activation of sperm for fertilization)

4) Secondary (antral)
- oocyte has COMPLETED ITS growth
- granulosa cells continue to proliferate
- granulosa cells produce follicular liquid (antrum)

5) Graafian follicle
- aka mature/vesicular follicle
- usu. only 1 activated follicle reaches this stage
- follicular liquid accumulates dramatically enlarging follicle to a diameter of 2+ cm
- forms a bulge on ovary surface called stigma

6
Q

When does follicle activation occur? What triggers it?

A

Follicle activation occurs at the start of the 28 day menstrual cycle, triggered by FSH. FSH triggers granulosa cells to produce aromatase (androstenedione to estrogen). Estrogen will then promote follicular cell mitosis.

7
Q

Blood vessels do not penetrate follicles. All signals that get to the primary oocyte have to cross the basement membrane, the granulosa cells, and the zona pellucida. How does this occur?

A

Gap junctions btw granulosa cells promote transport & signaling within the follicle.

Also, granulosa cells have filopodia that can reach thru zona pellucida to contact microvilli on the oocyte, making gap junctions.

8
Q

As liquid accumulates in secondary follicle, the oocyte and granulosa cells are pushed to the periphery. Near the oocyte, the granulosa cells are bunched together forming a mound called? What is the name for the granulosa cells that directly surround the oocyte?

A
  • cumulus oophorus = the mound of granulosa cells in which the oocyte is embedded
  • corona radiata = granulosa cells that directly surround the occyte
9
Q

The stroma around developing follicles rearranges to form theca folliculi. Describe the 2 components of the theca folliculi.

A

1) Theca externa (outer layer)
- provides structural support
- SM cells, fibroblasts, collagen fibers
- blends w/ stroma

2) Theca interna (inner layer)
- secrete androsteneidone
- extensive smooth ER, large mitochondria, lipid droplets
- foamy looking cytoplasm
- becomes highly vascular to transport hormones

10
Q

Follicular/granulosa cells undergo apoptosis. What about the oocyte?

A

autolysis

11
Q

What is corpus fibrosum?

A

later stages of atresia, BM thickens & collapses into the follicular space, leaving a mostly acellular collagenous scar called corpus fibrosum

12
Q

What are interstitial glands?

A

Theca interna cells that continue to produce hormones after atresia so they are called intersitital glands b/c they are not associated with a follicle.

13
Q

What triggers ovulation?

A

the rupturing of a graafian follicle releases oocyte from ovary into peritoneal space is triggered by LH surge –> positive feedback of estrogen.

14
Q

When does the primary oocyte (arrested in prophase I since birth until puberty) finishes the first meiotic division?

A

A few hrs prior to ovulation, the primary oocyte of graffian follicle completes the first meiotic division. This oocyte will commence its 2nd meiotic division but not complete it unless fertilization occurs.

15
Q

What is the oocyte complex?

A

The granulosa cells forming corona radiata remain attached to zona pellucida surrounding the expelled secondary oocyte = oocyte complex

16
Q

What does the ovulated follicle give rise to?

A

corpus luteum is formed after ovulation when the follicle wall collapses into folds and the antrum is infiltrated w/ clotted blood and then CT

17
Q

What is LH’s effect on granulosa cells and theca cells after ovulation?

A

LH causes granulosa and theca interna cells to differentiate into steroid hormone-producing luteinized granulosa and luteinized theca cells.

18
Q

What gives corpus luteum its yellow hue?

A

Lipochrome pigment accumulation in luteinized GRANULOSA cells gives corpus luteum its yellow hue

19
Q

Explain what happens to the corpus luteum without fertilization

A

after 10-12 days, corpus luteum requires further hormone stimulation or undergoes luteolysis (apoptosis). Macrophages engulf remaining debris. A large scar of dense CT will form, known as corpus albicans. This will last several months. Loss of progesterone –> trigger menstruation.

20
Q

Explain what happens to corpus luteum in case of pregnancy.

A

trophoblast cells forming the outermost layer of implanting embyro secrete hCG which prevents corpus luteum from undergoing luteolysis. Progesterone levels are sustained.