Histology of the Reproductive Tract Flashcards

1
Q

Describe the gross structure and function of the ovaries

A

Ovaries are atached to the posterior face of the broad ligament. The broad ligament is a wide double folded peritoneum that envelops the uterus, fallopian tubes and ovaries.

The ovaries are anchored to the uterus via the **ligament of ovary **and to the pelvic wall via the **suspensory ligament **

The fallapian tubes are intricately related to teh ovaries.

The ovaries are responsible for:

  • Producing gametes
  • Producing hormones
  • Responding to circulating hormones

Ovarian function declines with age and this is termed menopause

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Describe the histological structure of the ovaries

A

An ovary is divided into an:

  1. Inner medulla
    * ​loose connective tissue and blood vessels
  2. Outer cortex
  • location of ovarian follicles and oocytes
  • cortical stroma is composed of highly cellular connective tissue and smooth muscle cells

The surface of the ovaries are irregular due to the constant rupture and repair that occurs associated with the release of occytes in ovulation

Surface is simple epithelium (either squamous or cuboidal) continuous with mesothelium - 70% of ovarian tumours are from this epithelium

Directly beneath the epithelium is the tunica albuginea - a dense supportive connective tissue

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

How many oocytes are present in a female ovary over the course of time?

A

There are approximately 5 million / ovary in embryo and this reduces to 0.5 million by the time of birth - this is a female’s full compliment as she is unable to acquire more eggs than this.

Most of the oocytes present at birth die over the time of a persons life; a few thousand go through most of a maturation cycle.

Around 500 oocytes are ovulated into the fallopian tubes over the course of a females life

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Characterise primordial oocytes

A

Primordial oocytes are the smallest and earliest form of oocyte

They are lined by squamous follicular cells with themselves are contained within a common basal lamina

These oocytes are arrested in prophase of meiosis 1 (incomplete division)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Characterise a primary oocyte

A

The oocyte is now surrounded by the zona pellucida (inner aspect of follicular cells)

**The oocyte itself enlarges **

Follicular cells become cuboidal and multilayered granulosa cells / stratum granulosum

Surrounding stromal cells start to form stratum interna and externa

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Characterise a secondary follicle

A

As the stratum **granulosum **thickens a fluid filled cavity, known as theantrum, forms within the follicle and almost encloses the oocyte contained within.

The oocyte is suspended within the antrum by a stalk of granulosa cells called the cumulus oophorus

This circular layer of granulosa cells around the oocyte form the corona radiata after release

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Describe the events that lead to ovulation

A

Under an LH surge, the primary oocyte completes its first meiotic division to form a secondary oocyte

Associated with this is the rupturing of the follicle containing the oocyte - releasing the secondary oocytes into the body cavity to enter fallopian tube where it can survive for a maximal 24 hours if not fertilised

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What happens to a follicle once it releases its oocyte

A

Once a follicle ovulates it’s oocyte; it forms a corpus luteum

This occurs as the result of stromal, granulosa and thecal cells invading the cavity left by the oocyte and differentiating into luteal cells

**The **corpus luteum appears yellow due to lipid deposition, becomes vascularised and produced progesterone and estrogen to prepare and then maintain the endometrium

The deposited lipids are utilised on the synthesis of the hormones mentioned above

Corpus luteum survives for 14 days. If there is no fertilisation, it involutes with time -> transitioning through a non-functional stage of **corpus albicans **

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Characterise the histological structure of fallopian tubes

A

Fallopian tubes have:

External serosa (mesothelium + thin connective tissue layer)

Smooth muscle muscularis

**Mucosa **(epithelium + connective tissue)

The lumen of the fallopian tubes is lined by cilliated epithelium that assists in moving the oocyte towards the uterus. Fluid secreted from the epithelium and/or drawn from the peritoneum is used by the cilia to create a current, in conjunction with smooth muscle peristalsis, that moves oocyte/blastocyst towards uterus

Fertilisation usually occurs in the ampulla and the zygote travells in the isthmus for 4 days - during which time the fallopian tube provides nutrients for development in the secreted fluid

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Characterise the tissues of the uterine wall

A

The uterine wall of the uterus can be divided into three tissue layers: perimetrium, endometrium and myometrium

The perimetrium covers most of the external surface of the external surface.

Myometrium

Is composed of three layers of smooth muscle around the outside of the endometrium: the inner and outer layer is longitudinal muscle but the middle layer is circular and very vascular.

These smooth muscle cells are enlarged and in increased numbers during preganacy - remains after first pregnancy permanently as a thickened wall

Endometrium

Epithelial mucosa mix of ciliated and secretory columnar cells in simple epithelium

**Secretory glands** (no ciliated cells) penetrate into 
lamina propria (dense connective tissue)

Mucosa supplied by helical arteries

Functional layer sloughed off each menstrual cycle

Basal layer regenerates functional layer

Growth of the endometrium is driven by estrogen initially and breakdown by later decrease of estrogen and progesterone

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Compare the histological profile of the endometrium over the course fo the menstrual cycle

A

Over the course of the proliferative stages/secretory stages of mentrual cycle, the endometrium undergoes changes:

  • Epithelial, stromal (lamina propria) and vascular cells proliferate vigorously
  • Secretion accumulates (mucoid with glycogen)

In mid-proliferative phase glands of the endometrium become dilated and hypertrophied

In mid-secretory phase the glands have substance within them ready for implantation to occur

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Discuss the histology of the cervix

A

The **endocervix **is composed of simple columnar epithelium and it **highly glandular **like the body of the uterus.

Secretion is serous and copious at ovulation (conducive to sperm migration); thick and plug like at other times (non-conducive to sperm migration)

The ectocervix is composed of **stratified squamous epithelium **and is non-glandular like the skin/vagina

There is an abrupt transition between the simple columnar and stratified squamous epithlium - although the position of transition cahnges with reproductive state of female and stage of menstrual cycle.

HPV infects female in this region -> stratified epithelium sheds cells that are inspected by Pap smears for tumourous changes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Describe the histology of the vagina

A

The **vagina **is a **fibromuscular tube **

It is lined by non-keratinised stratified squamous epithelium (undergoes cyclic changes with menstrual cycle) and forms mucosa with partly erectile lamina propria

It’s smooth muscle layers comprise of a thin inner and thick outer layer (continuous with muscle of uterus - but no middle layer)

No glands are present - the vagina is lubricated by cervical glands or vestibule glands

The most superficial cells of the epithelium retain nuclei which predisposes them to malignancy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Characterise the structure of breasts

A

Breasts vary with age, menstrual cycle or reproductive status

They contain multiple mammary glands embedded in dense connective tissue and abundant adipose tissue (majority of breast volume is fat)

Multiple mammary glands each open onto the nipple through independent and seperate openings

Mammary glands consist of several important structures:

Terminal duct lobular units (TDLUs)

  • 15-20 lobular structures per mammary gland which contain acini that actually produce milk and interlobar connecting ducts to organise milk distribution

**Lactiferous ducts **

  • Branching network that delivers milk from lobules to the nipple for secretion

Mammary glands are modified sweat glands

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What differntiates the breast structure of males and females?

A

Until puberty, male and female mammary glands are similar

At puberty, male glands regress due to testosterone

At puberty, female glands grow due to estrogen and progesterone = extension of glands and breast enlarges (largely adipose tissue)

Note: mammary glands remain inactive until pregnancy as they are under negative influence of stromal cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Discuss the events and histology associated with inactive glands

A

Inactive Glands

  • are responsive to the menstrual cycle and under go growth and collapse with successive rounds of the menstrual cycles
    • in luteal phase -> become more columnar, some secretions appear and fluid accumulates in stroma connective tissue
  • immediately prior and during mestration the gland involute

Histologically:

Inactive gland relatively sparse, cuboidal/ columnar epithelial cells, surrounding
myoepithelial cells in extensive dense connective tissue

  • flattened myoepithelial cells contract the ducts to release milk
17
Q

What changes in breast structure occur in pregnancy?

A

Terminal ductules elongate and branch

Epithelial and myopeithelial cells
proliferate
from progenitor cells

By term, have large cuboidal epithelial
cells
containing lipid and secretory product
in lumen

Breast is enlarged as a result of growth

18
Q

Characterise the profile of milk secreted in lactation

A

Colostrum - a premilk substance

Human milk is mixture of low lipid, low carbohydrate and high protein

It is high in IgA (from plasma cells that have invaded intralobular tissue) which assists in passive immunity

The production of milk is stimulated by the hormone prolactin

Mature milk contains less Ig and higher amounts of CHO and lipids

19
Q

What mechanisms regulate lactation?

A

Suckling initiates a reflex that inhibits prolactin release-inhibiting hormone -> leading to the increased release of prolactin for milk production.

Suckling also releases oxytocin which acts to contract myoepithelial cells of mammary glands to squeeze milk out of TDLUs and lactiferous sinuses

20
Q

What happens to mammary glands following menopause?

A

Following menopause, mammary glands
involute

Secretory cells disappear leaving only ductal systems

These ductal systems tend to be the site of breast cancer

21
Q

Describe the structure of the testis

What is the pathway of sperm in ejaculation

A

Structures of the testis are surrounded by thick tunica albuginea connective tissue

This tunica albuginea is organised in septa that divied the testis into approximately 250 incomplete compartments

In each of these compartments is a seminiferous tubule (site of spermatogenesis) that connects to the epididymis via first the rete testis and then the efferent ductules.

The epididymis leads to the vans deferens which then enters the urethra

22
Q

Describe the histology of the seminiferous tubule

A

Each lobule of the testis contains 1 - 4 highly convoluted seminiferous tubules (~50 cm long)

They are lined by stratified epithelium where spermatogenesis occurs:

  • Spermatogonia are stem cells that produce spermatocytes to undergo meiosis and mature into sperm -> this process occurs as they migrate towards the tubule lumen
  • Sertoli cells anchor, support and provide nutrients to spermatids so they can mature and develop in the lumen

Tunica/lamina propria surrounds the seminferous tubules and contains:

  • Myoid cells = contractile smooth muscle like cells that propel sperm fluid and debris along tubule
  • Leydig cells = large testosterone secreting cells

The final section of the seminiferous tubule is the straight tubuli recti which is lined solely by sertoli cells before final cuboidal epithelium. It deposits tubule contents into the rete testis - an interconnected set of channels lined by ciliated cuboidal cells which communicate with epididymis via efferent ductules

23
Q

Describe the structure and function of the epididymis and efferent tubules

A

The epididymis is embryologically derived from the mesonepheric wolffian duct

The efferent ductules (derived from mesonepheric tubules) connect the epididymis to the rete testis

The epididymis is lined with pseudostratified
columnar epithelium surrounded by smooth muscle

It is 4-6 m long and highly coiled; consisting of a head, body and tail (efferent ductules connect to head)

24
Q

What is the function of the epididymis?

A

Sperm mature as the move along epididymis

This includes decapacitation, the inhibition of
the ability of the sperm to fertilise an egg
(reversed in vagina) mediated by inhibitory factors
secreted by epididymis

Epididymis also absorbs most testicular
fluid around sperm and **clean up debris **

25
Q

Describe the structure of the vas deferens

A

The vas deferen runs into the abdomen via inguinal canal as part of the spermatic cord

It passes over the lip of pelvis and descends to prostate at base of bladder – through prostate as
ejaculatory duct when combined with seminal vesicle.

It is lined with ciliated pseudostratified columnar epithelium and has a thick smooth muscle coat (except in ejaculatory duct)

26
Q

Describe the structure of the seminal vesicles

A

Seminal vesicle is a branch structure of the ductus deferens

It is lined by a thick mucosa and thin smooth muscle

Secrete a fructose and prostaglandin rich secretion (alkaline pH) to support sperm

It’s secretions contributes 50% of semen volume and modifies the acid (pH 4) environment of vagina

27
Q

Describe the prostate

A

The prostate is the largest accessory sex gland located on the anterior rectal wall inferior to the bladder.

A centrally penetrating urethra traverses the prostate with communicating prostatic sinuses.

The main prostatic glands of the prostate drain directly into the urethra via long ducts; whereas submucosal glands drain via the prostatic sinuses.

Paired ejaculatory ducts also penetrate the prostate and these are located inferiorly

Epithelium is heterogenous - containing mixed pseudostatified cuboidal or columnar eipthelium

28
Q

What are prostatic concretions?

A

The lumen of ducts running within the prostate gland can accumulate aggregations of protein, calcium phosphate, cholesterol and cellular debris - particularly with age

Stones of calcium phosphate, a component of prostatic secretions, can precipitate in prostate ducts and are considered relatively normal

29
Q

What is the function of the prostate?

A

Prostate produces a complex secretion that contributes to the formation of seamen.

Contains acid phosphatase, fibrolysin and
**coagulating factors **

  • Initially causes the ejaculate to clot
    (immobilising it) but then fibrolysin
    dissolves clot
    and frees sperm to move

Secretion pH is neutral and does not contribute significantly to alkalising the vagina - unlike the seminal vesicles

30
Q

Characterise the structure of the penis

A

The penis is composed of three erectile tissue masses:

2x corpus cavernosa and 1x corpus spongiosum

All three masses are surrounded by tunica albuginea - but the surrounding layer around spongiosum is not as thick

The urethra lies within corpus spongiosum

31
Q

How do erections work?

A

The three erectile masses of the penis are cavernous tissues with many ‘potential’ vascular spaces surrounded by smooth muscle.

Parasympathetic stimulation relaxes cavernosal smooth muscle and dilates the arteries supplying blood via ACh and NO

Swelling of the cavernous bodies compresses veins in the penis thereby restricting the outflow of blood.

Get detumescence (flacidity) by sympathetic stimulation reducing inflow and contracting cavernosal smooth muscle to expel present blood.

32
Q

Characterise the structure of the clitoris

A

The body of clitoris is comprised of bilateral corpus cavernosum tissues surrounded by tunica albuginea

Clitoral erection is thought to be the same as penile erection

33
Q
A