Female Reproductive System

Question 1

Label the anatomy of the female reproductive system?

Answer 1

Question 2

Functions of the ovaries?

Answer 2

1. Produce gametes (AKA oogenesis, in females)
2. Produce steroids, mainly oestrogens and progestogens (mainly progesterone)

Question 3

Structure of the ovaries?

Answer 3

Medulla - forms the core of the organ and contains loose CT, contorted arteries, veins and lymphatics; it is continuous with the hilum of the organ

Cortex - contains scattered ovarian follicles, in a highly cellular CT stroma. Outer shell is a dense CT layer (tunica albuginea), which is covered by a single layer of cuboidal cells (germinal epithelium)

Question 4

What is the germinal epithelium of the ovarian cortex?

Answer 4

AKA ovarian surface epithelium Holdover from a time when they were thought to give rise to gametes, i.e: the term germinal epithelium is a misnomer

Question 5

Development of female ova during the embryonic development of a female?

Answer 5

Early, around week 6, germ cells from the yolk sac invade the ovaries and proliferate, via mitosis, to form oogonia (small diploid cell that goes on to become a primordial follicle)

These undergo development and division, via meiosis, to form mature oocytes (AKA ova)

Question 6

Define oogenesis?

Answer 6

Development of oocytes (female germ cells), from oogonia

Question 7

Define folliculogenesis?

Answer 7

Growth of the follicle, which consists of the oocyte and any assoc. support cells

Question 8

No. of germ cells present, in both ovaries combined, during different stages of follicular development?

Answer 8

In a 6 week embryo, there are 1700 (in the form of germ cells)

At 7 months in utero, there are 5,000,000 (in the form of oogonia)

At birth, there are 1,000,000 (in the form of primary oocytes)

At puberty, there are 500,000 (in all types of follicles)

At menopause, there are few germ cells

Question 9

Apoptosis of oognonia and oocytes is termed what?

Answer 9

Atresia

The cell is resorbed following cell death

Question 10

Describe the process of meiosis beginning in the oocytes

Answer 10

Before birth, meiosis begins in the oocytes but it halts at prophase I

If the oocyte undergoes further development, meiosis will restart but many remain in this state for several decades (until fertilisation occurs, once a sperm is met)

E.g: in a 20 year old female, ~15 follicles restart development per day, dropping to ~1 per day in a 40 year old

Question 11

Stages in follicular development?

Answer 11

Pre-antral follicles:

1. Primordial follicle
2. Primary follicle
3. Late primary follicle

Antral follicles:

5. Secondary follicle
6. Mature Graafian follicle

Question 12

What cells must the oocyte assoc. with?

Answer 12

Pre-granulosa cells (follicle cells) - these are squamous but, if the follicle enters the growth phase, they become cuboidal If the oocyte fails to assoc. with these cells, it will die

Question 13

Structure of primary follicle?

Answer 13

Defined by the cuboidal granulosa cells (AKA follicular cells), forming the zona granulosa In the primary follicle, stromal cells are assoc. with the outside of the follicle and will go on to form the theca folliculi

The oocyte has enlarged and a layer of special EC matrix, the zona pellucida, is beginning to form between the oocyte and granulosa cells

Question 14

Further development of the primary follicle, into a late primary follicle?

Answer 14

Granulosa cell layer proliferates (this is a hallmark of late primary follicles, i.e: instead of having one granulosa layer, they have more), so now termed the theca folliculi

Inner layers of the adjacent stromal cells (theca folliculi) transform to form a layer, called the theca interna; this goes on to secrete oestrogen precursors, which will be converted to oestrogen by granulosa cells

Outer layers remain fibroblast-like and form the theca externa

Question 15

Development of the secondary follicle?

Answer 15

As the follicle enlarges, an antrum (space), filled with fluid, begins to form and enlarge in the granulosa cells layer, forming a secondary follicle

Overall, the follicle enlarges, as the antrum enlarges, and the granulosa and thecal layers (theca interna and theca externa) continue to proliferate

Question 16

What are Graafian follicles?

Answer 16

The very largest antral follicles; these can reach 20mm in diameter

NOTE - the cumulus oophorus is a cloud of granulosa cells surrounding the follicle

Question 17

What is the secondary oocyte and how does it form?

NOTE - this is note the same as a secondary follicle

Answer 17

1 day before ovulation, the oocyte in the largest Graafian follicle completes meiosis 1; instead of producing 2 equal cells, it produces:

• 1 cell called the secondary oocyte, which is similar in size to the original primary oocyte
• 1 tiny polar body, which carries the second nucleus away to degenerate

Question 18

Once the secondary oocyte forms, what happens to it?

Answer 18

It begins the 2nd phase of meiosis but stops at metaphase II

It will only complete meiosis to become a fully mature oocyte after it has been released (during ovulation) and fertilised by a sperm, resulting in production of a 2nd polar body

Question 19

What is follicle stigma?

Answer 19

Indicates imminent rupture of the follicle, resulting in release of the oocyte and the granulosa cells surrounding it, which are then referred to as the corona radiata

Question 20

What happens to the follicle after ovulation?

Answer 20

Transforms into the corpus luteum with the theca and granulosa cells secreting oestrogens and progesterone, helping to prepare the uterus for implantation

Question 21

What happens to the follicle if no implantation occurs?

Answer 21

Becomes a white-coloured CT, called the corpus albicans

Question 22

What happens to the follicle if implantation occurs?

Answer 22

Placenta secretes HCG, preventing degeneration of the corpus luteum for a time and so maintains progesterone levels, which, in turn, maintains the pregnancy

Question 23

Journey of the ovum, from the ovaries?

Answer 23

Funnel-shaped infundibulum moves so that its opening is adjacent to the site where the follicle ruptures

Ovum moves down the tube, propelled by gentle peristalsis and currents created by the ciliated epithelium; secretory cells in the epithelium secrete nutrients

Fertilisation usually occurs in the ampulla and the fertilised ovum is then transported to the uterus, for implantation

Question 24

Histology of the ampulla of the uterine tube?

Answer 24

Mucosa is folded and lined by simple columnar epithelium, with ciliated cells and secretory cells (both secretion and ciliogenesis are cyclic)

This is surrounded by smooth muscle (2 layers)

Question 25

Histology of the isthmus of the uterine tube?

Answer 25

Lining epithelium is mostly secretory with few ciliated cells There are 3 layers here in the isthmus

Question 26

Constituents of the uterine wall?

Answer 26

1. Inner secretory mucosa, called the endometrium, most of which is shed during menstruation; the endometrium is made up of tubular secretory glands embedded in a CT stroma 2. Coat of 3 layers of smooth muscle (layers often not very distinct), combined with collagen and elastic tissue, called the myometrium 3. Outer visceral covering of loose CT covered by mesothelium, the perimetrium

Question 27

Divisions of the endometrium?

Answer 27

Stratum functionalis - undergoes monthly growth, degeneration and loss; upper portion of the spiral artery goes into spasm and deprives the functionalis, which dies Stratum basalis - reserve tissue, which regenerates the functionalis; fed by straight arteries, so it survives and regenerates the functionalis, for the next menstrual cycle

Question 28

What happens to the endometrium during the proliferative phase?

Answer 28

Stratum basalis proliferates and glands, stroma and vasculature grow, increasing the thickness of the endometrium by reconstituting the stratum functionalis Proliferative phase continues until ~1 day after ovulation

Question 29

What happens to the endometrium during the secretory phase?

Answer 29

Glands become coiled, with a corkscrew appearance, and secrete GLYCOGEN

Question 30

Lining of the uterine glands themselves?

Answer 30

Pseudostratified columnar epithelium lines the glands, which are fairly straight Stroma is proliferating due to oestrogen

Question 31

What happens to the endometrium during the menstrual phase?

Answer 31

Arterioles in the stratum functionalis undergo constriction, depriving the tissue of blood; this leads to ischaemia, with resultant tissue breakdown, leakage of blood and tissue sloughing

Question 32

What is the cervix?

Answer 32

Short cylinder with a small lumen; it projects into the upper vagina

Question 33

Histology of the cervix?

Answer 33

Mostly fibrous CT, covered by stratified squamous epithelium on its vaginal surface; this TRANSITIONS to mucous-secreting, simple columnar epithelium

Question 34

Clinical importance of the transition zone in the cervix?

Answer 34

Common site of dysplasia Neoplastic changes, leading to cervical cancer, most frequently begin in the TZ

Question 35

What are the endocervical glands?

Answer 35

Mucous-secreting epithelium of the canal Secretions vary being thin and watery, in the proliferative phase (allowing passage of sperm), to thick and viscous, following ovulation (preventing passage of sperm or microorganisms)

Question 36

What happens when the outlets of the endocervical glands become blocked?

Answer 36

Glands expand with secretions, forming a Nabothian cyst

Question 37

4 layers of the vagina?

Answer 37

1. Non-keratinised stratified squamous epithelium - during reproductive years, this layer is thicker and cells are enlarge, due to glycogen accumulation 2. Lamina propria - CT rich in elastic fibres and thin-walled blood vessels 3. Fibromuscular layer - inner circular and outer longitudinal smooth muscle 4. Adventitia

Question 38

How is the vagina lubricated?

Answer 38

There are no glands in the wall of the vagina but it is lubricated by: * Mucous from the cervical glands * Fluid from the thin-walled blood vessels of the lamina propria

Question 39

Why does the stratified squamous epithelium of the vagina look watery?

Answer 39

Due to glycogen production The glycogen is metabolised by commensal bacteria, to lactic acid, which inhibits the growth of pathogenic bacteria

Question 40

Components of the external genitalia in females?

Answer 40

Mons pubis Labia majora Labia minora Clitoris

Question 41

What is the mons pubis?

Answer 41

Skin that contains highly oblique hair follicles; these produce coarse, very curly hair (characteristic of pubic hair) This overlies a substantial subcutaneous fat pad, which itself overlies the pubic symphisis

Question 42

What is the labia majora?

Answer 42

Extensions of the mons pubis, similar structure and rich in apocrine sweat glands and sebaceous glands and with small bundles of smooth muscle Hair follicles are present on the outer surface but not on the inner

Question 43

What is the labia minora?

Answer 43

Thin skin folds that lack subcutaneous fat and hair follicles; rich in vasculature and sebaceous glands that secrete directly onto the skin surface Keratinised epithelium extends into the vaginal opening, to the level of the hymen where there is a transition to non-keratinised stratified squamous epithelium

Question 44

What is the clitoris?

Answer 44

Contains 2 tubes of erectile vascular tissue (corpora cavernosa), covered by a fibrocollagenous sheath; this, in turn, is covered by skin with rich innervation and a thin epidermis