Histology Flashcards
What are the 2 main roles of the ovary?
Produce gametes (oogenesis in females)
Produce steroids, mainly oestrogens and progestogens
What are the 2 main layers of the ovarian structure?
A medulla and a cortex
What does the ovarian medulla contain?
loose connective tissue tortuous vessels (arteries, veins and lymphatics)
What does the cortex of the ovary contain?
- scattered ovarian follicles
- highly cellular connective tissue stroma.
- outer ‘shell’ of the cortex = dense connective tissue layer called the tunica albuginea
What is the name given to the single layer of cuboidal cells covering the outside of the tunica albuginea?
germinal epithelium
What is the clinical relevance of the germinal epithelium?
Many ovarian cancers arise from this small layer
What is the blood supply to the ovary?
Helicine arteries
- these enter the hilum from the broad ligament and supply blood to the ovary
Germ cells migrate from the yolk sac to the ovaries to become what type of cells?
Oogonia
How are oocytes formed?
Meiosis division of oogonia (oogenesis)
What is meant by folliculogenesis?
growth of the follicle which consists of the oocyte and any associated support cells.
When are most oogonia (precusors to oocytes) present in a females ovaries?
7 months in utero
Where in meiosis do the oocytes halt and why?
Prophase I
further development is only required if that oocyte becomes the dominant one (i.e. for ovulation)
=> many will remain in this state for several decades
Describe the different types of follicle found during follicle development
Primordial
Primary (early/late)
Secondary
Mature Graafian follicle
Why is it important for an oocyte to associate with the flat cells surrounding it during its development?
If it does not associate with Pregranulosa cells it will die
- these cells become cuboidal upon the oocyte entering the growth phase
What layer of extracellular matrix between the oocyte and granulosa cells is visible in a primary follicle?
Zona Pellucida
In a late primary follicle, what layers begin to form outside of the granulosa cell layer?
theca interna - goes on to secrete oestrogen precursors, converted to oestrogen by the granulosa cells (GC).
Theca Externa = outer layer, fibroblast-like
What can be seen in a secondary follicle?
Antrum (new space) becomes filled with follicular fluid
- forms and enlarges in the granulosa cell layer
=> forming a secondary follicle
Explain how meiosis progresses in the dominant follicle for ovulation
- oocyte in the largest Graafian follicle will complete meiosis 1
- produce one cell called a secondary oocyte, similar in size to primary oocyte
- also produces a tiny polar body that carries the second nucleus away to degenerate.
What is the follicular stigma?
- pressurised area of ovary where tunica albuginea is parted aside
=> indicating imminent rupture of the follicle. - This will release the oocyte and the granulosa cells that surround it
How does pregnancy prevent the degeneration of the corpus luteum?
If implantation occurs, the placenta secretes HCG which prevents degeneration of the corpus luteum
=> CL maintains progesterone levels, which maintains the pregnancy
Describe the epithelium in the fallopian tubes and how this is useful?
- ciliated epithelium
- Secretory cells in the epithelium secrete nutrients.
=> egg can be given nutrients and moved down the tube by cilia towards the uterus
Describe the histological appearance of the ampulla of the uterine tube
- mucosa is highly folded
- lined by simple columnar epithelium
- ciliated cells and secretory cells
- surrounded by smooth muscle
What are the 3 layers of the uterus?
Endometrium (glandular tissue and stroma)
Myometrium (3 layers of smooth muscle
with collagen and elastin)
Perimetrium (loose connective tissue covered by mesothelium)
What are the two layers of the endometrium and what are their functions?
Stratum Functionalis (F) which undergoes monthly growth, degeneration and loss. - arteries in this tissue constrict to allow for shedding
Stratum Basalis (B) which is a reserve tissue that regenerates the functionalis. - arteries in this tissue do not constrict, but help to regenerate the above tissue
Describe the appearance of uterine glands in the secretory phase?
coiled with a corkscrew appearance and secrete glycogen
Describe the change of epithelium in the cervical canal and what the clinical relevance of this site is
Changes from simple columnar epithelium to stratified squamous epithelium towards the outside of the body
This transition zone is a common site of dysplasia, and neoplastic changes leading to cervical cancer
What type of fluid is secreted by the endocervical glands?
- thin and watery in the proliferative phase (allowing the passage of sperm)
- thick and viscous following ovulation (preventing the passage of sperm, or microorganisms)
A blockage of the endocervical glands can cause what?
Nabothian cyst
What are the four histological layers in the vaginal walls?
- Non-keratinized stratified squamous epithelium (appear clear due to glycogen accumulation)
- Lamina propria: connective tissue rich in elastic fibres
- Fibromuscular layer: inner circular and outer longitudinal smooth muscle.
- Adventitia
How are the vaginal walls lubricated if there are no glands in the vaginal wall?
- lubricated by mucous from the cervical glands AND fluid from the thin walled blood vessels of the lamina propria
How does the accumulation of glycogen in the vaginal walls contribute to preventing infection?
Commensal bacteria metabolize the glycogen to lactic acid which inhibits the growth of pathogenic bacteria.
Describe the hair follicles found in the mons pubis
- highly oblique hair follicles
=> produce coarse, very curly hair - overly fat pad which itself overlies the pubic symphysis
What type of glands are found on the labia majora?
apocrine sweat glands and sebaceous glands
Describe the histological make up of the clitoris?
- two tubes of erectile vascular tissue
- covered by a fibrocollagenous sheath
Describe the differences between the labia majora and minora
lack subcutaneous fat and hair follicles
BUT are rich in vasculature and sebaceous glands
