Histology Flashcards
What are the functions of the ovary
Produce gametes
Produce steroids - oestrogens and progesterone’s
Describe the structure of the ovary
Has a medulla and cortex
Medulla is the core and contains loose connective tissue, contorted arteries, veins and lymphatics
Cortex has a connective tissue stroma with ovarian follicles scattered through
Has a dense outer layer called the tunica albuginea
This is covered by a single layer of cuboidal cells called the germinal epithelium
Which layer do a lot of ovarian cancers develop from
The germinal epithelium
Outer layer
How do the oocytes develop
Germ cells invade the stroma of the developing ovary
They multiply lots to form the mature oocytes
What is oogenesis
It’s the development of oocytes, the female germ cells, from oogonia.
What is folliculogenesis
It is the growth of the follicle, which consists of the oocyte and any associated support cells.
At what stage of life does the number of eggs reach its peak
Around 7 months in utero
Atresia then occurs and some die off
When does meiosis of oocytes start and stop
Meiosis starts in the oocytes before birth but stops at prophase 1
If the oocyte develops further (i.e. is ovulated) meiosis will restart
Oocytes can stay in the halted prophase for decades
Describe how follicles develop
Cuboidal granulosa cells form the primary follicle
Stromal cells associate with the outer layer and go on to form the theca folliculi
Oocyte enlarges and zona pellucida forms around it
The granulosa cells proliferate
The inner layer of stromal cells transform into the theca interna
The outer layers remain fibroblast-like and form the theca externa.
Follicle enlarges and a space called the antrum forms in the granulosa layer
This fills with follicular fluid and forms a secondary follicle
What name is given to the largest and most mature follicles
Graafian follicles
What happens to the Graafian follicle just prior to ovulation
One day before the largest Graafian follicle will complete meiosis 1
Instead of producing 2 equal cells it produces the secondary oocyte and a tiny polar body that carries the second nucleus away to degenerate
The secondary oocyte then undergoes meiosis 2 and stops at metaphase II
When does the secondary oocyte complete meiosis 2
Only once it has been released by ovulation and fertilised by a sperm
On completion it produces another polar body
What happens to the follicle after ovulation
It transforms into the corpus luteum
The remaining theca and granulosa cells secrete oestrogens and progesterone to prep the uterus for implantation
What happens to the corpus luteum if an embryo does not implant
It breaks down and becomes the corpus albicans
This is white connective tissue structure
This occurs after around 14 days
What happens to the corpus luteum if an embryo does implant
The placenta will secerete HCG to maintain the corpus luteum so that progesterone levels are maintained
This helps maintain the pregnancy
Placenta eventually takes over
How does the oocyte move down the fallopian tube
Propelled by gentle peristalsis of the tube
The tube also has ciliated epithelium which create currents to help it move
What cells are found in the fallopian tubes
Ciliated epithelium - creates a current
Secretory cells - secrete nutrients
Do the fallopian tubes have muscles
They have 2 layers of smooth muscle in the ampulla
3 layers in the isthmus
What makes up the uterine wall
Inner mucosa of endometrium - made up of tubular secretory glands embedded in a connective tissue stroma
3 layers of smooth muscle called the myometrium
An outer visceral covering of loose connective tissue covered by mesothelium, the perimetrium
How is the endometrium divided
Stratum Functionalis which undergoes monthly growth, degeneration and loss.
Stratum Basalis which is a reserve tissue that regenerates the functionalis
What happens to the endometrium during the proliferative phase
Stratum basalis proliferates and glands, stroma and vasculature grow
Thickness increases by reconstituting the stratum functionalis
This is triggered by oestrogen
What happens to the endometrium during the secretory phase
The glands become coiled with a corkscrew appearance and begin to secrete glycogen
This is triggered by the release of progesterone after ovulation
What causes endometrial shedding
Arterioles in the stratum functionalis undergo constriction, depriving the tissue of blood and causing ischemia, with resultant tissue breakdown, leakage of blood and tissue sloughing.
What is the cervix made up of
Mostly fibrous connective tissue covered by stratified squamous epithelium
It transitions to mucous secreting simple columnar epithelium on the internal side
What is the clinical significance of the transition zone of the cervix
It is a common site of dysplasia and neoplastic changes
Cervical cancers most frequently start here
What is secreted from the endocervical glands
Varies throughout the cycle
Is thin and watery mucous in the proliferative phase - allows sperm to enter
Is thick and viscous after ovulation
What can happen if the endocervical glands become blocked
They expand with secretions and form a Nabothian cyst
List the layers of the vagina
Non-keratinized stratified squamous epithelium
Then lamina propria - connective tissue rich in elastic fibres and thin walled blood vessels
Fibromuscular layer
Adventitia
How is the vagina lubricated
There are no glands in the vaginal
It is lubricated by mucous from the cervical glands
How does the vagina protect itself from infection
It has glycogen in the walls which commensal bacteria convert into lactic acid
This inhibits the growth of pathogenic bacteria
Describe the structure of the mons pubis
Skin which contains thick hair follicles - pubic hair
Underneath is a substantial subcutaneous fat pad which itself overlies the pubic symphysis
Describe the structure of the labia majora
Extensions of mons pubis, similar structure and rich in apocrine sweat glands and sebaceous glands and with small bundles of smooth muscle
Has hair follicles on the outer surface but not inner
Describe the structure of the labia minora
Thin skin folds that are rich in vasculature and sebaceous glands
Keratinized epithelium extends into the opening of the vagina to the level of the hymen
Describe the structure of the clitoris
two tubes of erectile vascular tissue (corpora cavernosa), covered by a fibrocollagenous sheath covered by skin with rich innervation and a thin epidermis
What is a normal endometrial thickness for a women of reproductive age
Thickness goes from around 5mm up to 11mm in the proliferative phase
Can reach up to 16mm
