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Histology / Embryology Unit 4 > Female Reproductive System > Flashcards

Flashcards in Female Reproductive System Deck (73)
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What covers the ovaries?

1. A dense CT capsule, the tunica albuginea
2. A layer of mesothelium (cuboidal / squamous) on the outside


What are the two parts of the ovary and what is found in them?

1. Outer cortex - portion beneath tunica albuginea. Consists of ovarian follicles + stroma
2. Medulla - central core, consists of loose connective tissue, blood vessels, lymph vessels, and nerves

No distinct boundary


What is the ovarian stroma?

Connective tissue containing collagen fibers, ground substance, smooth muscle cells, and fibroblast like cells which is found in the outer cortex


What type of oocyte do primordial follicles have?

One oocyte arrested in prophase 1 of Meiosis 1 (diplotene stage). Called primary oocyte. They can stay in this phase for 12-50 years.


What type of cells surround the oocyte in primordial follicles? What surrounds them?

A single layer of squamous cells called follicular cells. They are surrounded by a basal lamina, which is surrounded by the connective tissue of the ovarian cortex.


What are the two types of primary follicles?

1. Unilaminar primary follicle - early stage, 1 layer of granulosa cells
2. Multilaminar primary follicle - later stage, 3-5 layers of granulosa cells


What changes occur from primordial to primary follicle?

1. Squamous follicular cells become cuboidal granulosa cells, which can have multiple layers
2. Primary oocyte secretes zona pellucida, between it and the granulosa cells
3. Cortical granules appear in the ooplasm of the primary oocyte via TEM
4. Gap junctions are made between microvilli of oocyte and granulosa cells, and also between neighboring granulosa cells. This is for transfer of metabolites.
5. Theca begins to form.


What is the Zona Pellucida and how does it stain?

The layer forming in the primary follicular stage consisting of four major glycoproteins ZP1-4, secreted by the primary oocyte. It is between granulosa cells and oocyte.

Stains pink / red with H&E, and magenta with PAS (glycoprotein)


What are cortical granules for?

They contain proteases that are released if the oocyte is fertilized by sperm. Cortical reaction is used to block multiple fertilization events


What are theca cells, their two types, and when do they form?

They are connective tissue cells surrounding the basal lamina of the granulosa cells.
Theca interna: well vascularized with endocrine characteristics
Theca externa: less well vascularized, blends in with CT stroma of ovarian cortex

They form in the primary follicular stage but are best seen in secondary follicular


What changes occur from primary follicle to secondary (antral) follicle?

1. Primary follicle moves deeper into cortex due to increase in size from proliferation of granulosa cells.
2. Antrum appears among granulosa cells.
3. Theca layers become well defined.
4. Cumulus oophorus / cumulus mass forms
5. Oocyte stops increasing in size.
6. Corona radiata forms
7. Estrogen stimulates granulosa proliferation, increasing follicular size


What factors stimulate the growth of the primary follicle?

FSH, growth factors, and calcium


What stops the oocyte from increasing in size during the antral stage?

oocyte maturation inhibitor (OMI) that is secrete by the granulosa cells into the antral fluid


What forms the cumulus mass?

When a mound of granulosa cells becomes eccentrically located in the secondary / antral follicle


What is the corona radiata?

Granulosa cells of the cumulus mass that immediately surround the oocyte and remain with it during ovulation


What fluid fills the antrum?

Liquor folliculi - composed mainly of hyaluronic acid, as well as other hormones and growth factors such as oocyte maturation inhibitor


What is the function and stimulation of the theca interna cells?

Steroid-secreting endocrine cells which have receptors for luteinizing hormone (LH). They synthesize and secrete androgens + some progesterone, which pass through the basal lamina and are uptaken by granulosa cells


What do granulosa cells do under FSH control?

Convert the androgen androstenedione from theca interna cells into estradiol. Estrogen stimulates granulosa cell proliferation, increasing the size of the follicle.


During what stage do granulosa cells start to get LH receptors?

Secondary / antral stage


What characterizes the Graafian follicle stage?

1. Large antrum, zona pellucida, and detachment of oocte and corona radiata from rest of cumulus oophorus.
2. Completion of Meiosis I up until Metaphase II prior to ovulation due to LH surge.


What is released during ovulation?

Secondary oocyte, granulosa cells of corona radiata, and granulosa cells of the cumulus mass.


What happens to the lumen of the corpus luteum, which was occupied by the antrum of the follicle?

It is replaced by a blood clot and then by connective tissue.


What do the theca interna and granulosa cells become in the corpus luteum? How do they appear?

Theca interna: Theca lutein cells - small, less cytoplasm, basophilic
Granulosa: Granulosa lutein cells - large, eosinophilic
The theca cells invade into the granulosa and appear as strands.


What is meant by "luteinization"?

Luteinization = cells become filled with lipid, induced by LH surge. This works because both granulosa cells and theca interna cells now possess LH receptors. Both cell types will now produce mainly progesterone and some estrogen.


What is the corpus albicans?

If pregnancy does not happen, and the corpus luteum is not maintenanced by hCG, the luteinized cells become and irregular, highly folded, glassy, eosinophilic structure called corpus albicans.

Most of the cells left are macrophages.


What are atretic follicles?

Primordial follicles which start development as primary follicles, but do not develop into mature ova (only 400 mature ova out of 600,000-800,000 primordial at birth.). They degenerate via atresia.


What happens to form atretic follicles?

1. Apoptosis of granulosa cells.
2. Granulosa cell layer invaded by neutrophils and macrophages.
3. Granulosa cells slough into antrum
4. Theca interna hypertrophy
5. Follicle collapses as degeneration continues.
6. Connective tissue invades into follicle cavity.


What types of atretic follicles can be seen and how are they distinguished from the corpus albicans?

Only ones larger than primary follicles.
1. Zona pellucida will be recognizable as an eosinophilic band.
2. Corpus albicans is much larger and thicker, with no ZP
3. Basal lamina thickens, folds, and becomes eosinophilic as a "glassy membrane" in atretic follicles.


What are the four regions of the uterine tube and what characterizes them?

1. Infundibulum - funnel-shaped with fimbriae, which move close to surface of ovary at time of ovulation for uptake of oocyte.
2. Ampulla - longest segment, where fertilization takes place
3. Isthmus - narrow region near uterine wall
4. Intramural (uterine part) - opens into cavity of uterus


What cells characterize the mucosa of the uterine tube?

Simple columnar epithelium
1. Ciliated columnar - for motion of the oocyte
2. Non-ciliated columnar - Peg cells - secrete fluid containing nutrients for spermatozoa and ova