3.4 Histology of the female reproductive system

Question 1

What are the characteristics of the surface (germinal epithelium) of the ovary?

Answer 1

Simple cuboidal epithelium (continuous with mesothelium at hilum):
• Covers the free surface of the ovary • Rests on tunica albuginea (mesothelium; connective tissue

Question 2

What are the characteristics of the cortex of the ovary

Answer 2

Ovarian follicles (various stages of development) in a reticular stroma

Question 3

What are the characteristics of the medulla of the ovary

Answer 3

Connective tissue with blood vessels held in a loose stroma → continuous with hilum (entry/exit of vessels, lymphatics, nerves)

Question 4

[oogenesis: foetal life]
_____________ (in the yolk sac) in the foetus migrate to the ovary during embryonic development to give rise to oogonia:
• Oogonia: stem cells which divide by __________ in foetal life (do not multiply after birth) → enlarge to form _________________
o About 1 million oogonia are present at birth (degenerate and become fewer with increasing age)
• Primary oocyte: begins 1st meiotic division (arrested in _________________)

Answer 4

Primordial germ cells;

mitosis;

primary oocyte;

prophase I

Question 5

[oogenesis: post puberty]

\_\_\_\_\_\_\_\_ increases (ready for ovulation) and primary follicle develops: 
• Primary oocyte: continues \_\_\_\_\_\_\_\_\_\_\_\_ to form secondary oocyte (larger daughter cell) and \_\_\_\_\_\_\_\_\_\_\_ (degenerates)
o ~5 – 30 primary oocytes begin to mature every menstrual cycle and complete their 1st division shortly before ovulation
o Only 1 reaches maturity and ovulates (Graafian follicle), while the remaining degenerate
o Throughout the female reproductive life, only about 400 ova are discharged out of 40000 primary oocytes available 

• Secondary oocyte: immediately begins the 2nd meiotic division (arrested in _________________) → ovulation
o If fertilisation occurs: ________________
o No fertilisation: _______________

Answer 5

FSH;

1st meiotic division;

smaller polar body;

metaphase II;

secondary oocyte completes meiosis;

oocyte degenerates ~24h after ovulation

Question 6

what are the different stages of the follicular development?

Answer 6

The ovarian follicle consists of follicular cells surrounding the ova (aids development of ova):
• Passes through different stages as it matures: primordial → primary → secondary → mature Graafian follicles → release of ovum (ovulation)

Question 7

[primordial follicle]
The primordial follicle consists of the _________________, and is the smallest and simplest structure in the peripheral cortex:
• Numerous primordial follicles are present at birth → only further develop at puberty
• Surface of ovary contains many large cells (oocytes) → some stromal cells (follicular/granulosa cells → appear like spindles) around the oocyte condense to form a thin layer

Answer 7

oocyte and surrounding follicular cells;

Question 8

[primary follicle]
FSH released during puberty causes the oocyte ____________ and the flattened follicular cells to become more __________________ → progresses to form multiple layers:
• Presence of a distinct basement membrane which separates the follicular cells from the surrounding stroma

Answer 8

increase in size;

columnar (appear glandular)

Question 9

[unilaminar primary follicle]

what is the characteristic of it?

Answer 9

Single layer of columnar follicular cells surrounding the oocyte

Question 10

[multilaminar primary follicle]

what is the characteristic of it?

Answer 10

Multi-layered follicular part with the zona pellucida (glycoprotein layer forming a distinct eosinophilic membrane between the follicular cells and oocyte)

Question 11

[secondary follicle]

Continuous FSH secretion causes primary follicle to increase in size to form secondary follicle:
• Follicular/granulosa cells increase in layer thickness → extracellular spaces appear
- Granulosa cells are separated to form the antrum (follicular cavity) filled with _______________
- __________ cannot be visualised
• Stromal cells adjacent to the follicle differentiate into 2 layers:
- Theca interna: Inner stromal cells which increase in size, acquire ___________ (important for production of steroid hormones) → secrete ____________
- Theca externa: Thin layer of compact cells with no known secretory activity

Answer 11

follicular fluid rich in hyaluronic acid;

Oocyte;

sER and tubular cristae;

oestrogen

Question 12

[graafian follicle]

The Graafian (mature) follicle is ready for ovulation:
• Antrum of the follicular cavity is surrounded by a layer of \_\_\_\_\_\_\_\_\_\_
• Oocyte is surrounded by the \_\_\_\_\_\_\_\_\_\_\_\_\_ (mask of granulosa cells projecting into the antrum

Answer 12

granulosa cells;

cumulus oophoricus

Question 13

[graafian follicle]

What is the characteristic of the zona pellucida?

Answer 13

Pink distinct membrane-like layer around the oocyte

Question 14

[graafian follicle]

What is the characteristic of the corana radiata?

Answer 14

Thin layer of granulosa cells adjacent to the zona pellucida

Question 15

[graafian follicle]

What is the characteristic of the theca interna & externa?

Answer 15

Lies outside of the granulosa cell layer:

• Theca interna is a vascular structure; secretes oestrogen

Question 16

[graafian follicle]
During ovulation, the Graafian follicle ______________ and ruptures to release the ovum into the peritoneal cavity:
• Ovum (with _______________) is released along with follicular fluid (from the antrum)
• Secondary oocyte is picked up from the peritoneal cavity by the _______________ → travels along the Fallopian tube towards uterine cavity

Answer 16

bulges out of the ovarian surface;

corona radiata;

fimbriated end of the Fallopian tube

Question 17

[corpus luteum]
The ruptured Graafian follicle transforms into the corpus luteum (luteinisation) under the influence of ______ and begins to secrete _________________:
• Immediately after ovulation, bleeding in the follicular cavity forms the ________________ → transforms into the corpus luteum (full-fledged endocrine organ)
• Blood vessels from the ________________ enter the corpus luteum to make it vascular
• Continues functioning until several weeks later → placenta takes over in pregnancy

Granulosa cells: Become larger, more polyhedral with more cytoplasm, appearing yellowish grossly and acquires _______________ → granulosa luteal cells → _______________

Theca interna cells (some) Become theca luteal cells → _______________

Answer 17

LH;

progesterone;

corpus haemorrhagicum;

theca interna

lipids, sER and mitochondria;

PROGESTERONE ;

OESTROGEN (same as before)

Question 18

[corpus albicans]
The corpus luteum reaches its maximum size around day 20 and undergoes involution (to form the corpus albicans) → corpus luteum persists if fertilisation occurs though:
• Involution: cells decrease in number → corpus luteum replaced by ________________ via apoptosis (no inflammation)
• By day 26: hormone production decreases or ceases → no more oestrogen or progesterone is produced (cannot maintain the thickness of the endometrial lining)

Answer 18

acellular hyaline fibrous tissue (scar tissue)

Question 19

what type of cells are at the ovarian end?

Answer 19

Ciliated: Contributes to the movement of ovum through infundibulum and ampulla (tubal peristalsis still plays a greater role)

Question 20

what type of cells are at the uterine end?

Answer 20

Secretory: Produces watery tubal fluid with nutritive function for spermatozoa and the fertilised ova

Question 21

what is the characteristic of the perimetrium?

Answer 21

Serous layer of visceral peritoneum (covers outer uterine surface)

Question 22

what is the characteristic of the myometrium?

Answer 22

Thick wall of smooth muscle with 3 ill-defined layers (inner longitudinal, middle circular, outer longitudinal)

Question 23

what is the characteristic of the endometrium?

Answer 23

Mucosal lining on the inner aspect with cyclical changes (divided into the basalis and the functionalis)

Question 24

The endometrial proliferative phase corresponds to the ovarian follicular phase, and responds to the ____________ produced by the ___________:
• Leads to synchronous proliferation of glands, stroma, blood vessels
• Tubular glands are originally straight → proliferation of the glands is faster than that of the surrounding stroma → glands become ________________
o Glands are lined with _____________ (with ______________ nuclei) and mitoses (suggest proliferative activity)
• Mitoses are also found in ____________ (suggest stromal proliferation)

Answer 24

oestrogen;

ovaries;

slightly coiled ;

pseudostratified columnar cells ;

elongated dark ;

stromal cells

Question 25

A ____________ is released just before ovulation occurs, causing rupture of the Graafian follicle and release of the ovum into the Fallopian tube:
• Ovarian luteal phase: corpus luteum forms from the ruptured follicle → secretes __________________ (triggers the endometrial secretory phase)
• Endometrial glands: characterised by _____________ nuclei (compared to proliferative phase with elongated nuclei and dense chromatin)

• Early secretory: Subnuclear vacuoles (vacuoles within the gland, underneath the nuclei and between the basement membrane)
• Mid-secretory Glands are more coiled with luminal secretions and stromal oedema
• Late secretory: Pseudodecidual changes begin around spiral arteries in the stroma

Answer 25

surge of LH ;

progesterone and oestrogen;

rounded and vesicular;

Question 26

The corpus luteum involutes (if there is no fertilisation) and causes abrupt withdrawal of oestrogen and progesterone (maintains endometrium in the follicular and luteal phases):
• Menstrual bleeding occurs and the ________________ is shed while the _______________ is preserved (for endometrial regeneration)
• Glands and stroma crumble and disintegrate with fibrin thrombi seen

Answer 26

stratum functionalis ;

stratum basalis

Question 27

what is the type of epithelium at the endocervix?

Answer 27

Simple mucinous columnar epithelium with mucous glands in stroma (underlying the epithelium)

Question 28

what is the type of epithelium at the ectocervix?

Answer 28

Stratified squamous epithelium (forming the outer aspect of cervix projecting into the vagina)

Question 29

The squamocolumnar junction is where the ______________ meets the ___________________ → corresponds to the external os:
• Transformation zone: area where the endocervical epithelium is replaced by the squamous epithelium (squamous metaplasia → for protection)
• Keeps migrating along the length of cervix (metaplasia is reversible)
• Eversion of cervix: squamocolumnar junction moves outwards into the __________________(exposed to the acidic environment → physiological metaplasia

Answer 29

squamous epithelium (of the ectocervix);

columnar epithelium (of the endocervix);

vaginal portion of the cervix

Question 30

The vagina is a fibromuscular tube which is made of an inner mucosa, middle fibromuscular stroma and outer adventitia:

Mucosa: ____________________ epithelium (resting on lamina propria → connective tissue rich in vessels):
• Epithelium is thin before puberty and after menopause
• Glycogen content is the highest during ovulation → broken down by commensal bacteria to form ________________→ produces acidic pH in the vagina (protects against pathogenic fungi e.g. Candida)

Answer 30

Non-keratinising glycogenated stratified squamous ;

lactic acid