HIstology of Female Reproductive Tract Flashcards
2 main roles of the ovary?
produce gametes (oogenesis) produce steroids (oestrogens and prgesterone, mainly progesterone)
general structure of ovary?
inner medulla (core) containing loose connective tissue, contorted arteries, veins and lymphatics and is continuous with the hilum of the organ
outer cortex containing scattered follicles in a highly cellular connective tissue stroma
outer shell of cortex is a dense connective tissue layer called the tunica albuginea which is covered by single layer of cuboidal cells called germinal epithelium
blood supply to ovary?
group of helicine arteries enter the hilum from the broad ligament and supply blood to the organ
outermost layer of ovary?
superficial fibrous cortex (tunica albuginea) covered by germinal epithelium
where do germ cells originate?
invade ovaries from the yolk sac around week 6 and proliferate by mitosis to form oogonia
these cells will undergo development and division via meiosis to from mature oocytes which are termed ova
what is oogenesis?
development of oocytes from oogonia
what is folliculogenesis?
growth of the follicle which consists of oocyte and any associated support cells
describe the number of germ cell present at each stage of life
6 week embryo = 1700 (germ cells) 7 month foetus = 5,000,000 (oogonia) birth = 1,000,000 (primary oocyte) puberty = 500,000 (all types of follicles) menopause = few left
what is the process of loosing oocytes and oogonia called?
atresia (apoptosis based)
not all follicles progress to full development, true to false?
before birth, meiosis begins in oocytes but halts at prophase 1
if the oocyte undergoes further development, meiosis with restart but many will remain in this state for several decades
how does the number of follicles which restart development each day change with age?
in a 20 year old = around 15 follicles restart development every day
drops to around 1 per day in a 40 y/o
describe histology in primordial follicle
primary oocyte surrounded by follicle cells (pregranulosa cells)
stroma cells fill space in between oocytes/follicle cells
describe primary follicle?
cuboidal granulosa cells surround the follicle (zona granulosa)
the oocyte has enlarged inside the follicle and a layer of special extracellular matrix (zona pellucida) is beginning to form between the oocyte and granulosa cells
how does the primary follicle change with development?
granulosa cell layer proliferates
inner layers of the adjacent stromal cells (theca folliculi) transform to form a layer called the theca interna which will go on to secrete oestrogen precursors which will be converted to oestrogen by granulosa cells
outer layer remain fibroblast-like and form the theca externa
describe the secondary follicle?
follicle enlarges further and a follicular fluid filled space called the antrum forms and enlarges in the granulosa cell layer forming a secondary follicle
overall the follicle enlarges as the antrum enlarges and the granulosa and thecal layers (interna and externa) continue to proliferate
how is the dominant follicle chosen and what happens?
one day before ovulation, the oocyte in the largest graafian follicle (largest antral follicles) will be selected
this will complete meiosis 1 and produce one secondary oocyte (similar size to primary oocyte) and one tiny polar body (carries 2nd nucleus away to degenerate)
secondary oocyte begins 2nd phase of meiosis but stops at metaphase 2
only complete meiosis to become fully mature oocyte after it has been released (ovulation) and fertilized by a sperm (producing a 2nd polar bodY)
when does second mitotic division occur in the oocyte?
when cell encounters sperm
what happens in the follicle after ovulation occurs?
follicle transforms into corpus luteum with the theca and granulosa cells secreting oestrogens and progesterone which helps prepare the uterus for implantation
what happens to follicle if no implantation occurs?
corpus luteum becomes a white coloured connective tissue called corpus albicans
what happens to follicle if implantation occurs?
placenta secretes HCG which prevents degeneration of corpus luteum for a time and so maintains progesterone levels which in turn maintains the pregnancy
how do the uterine tubes/oviducts/fallopian tubes work?
funnel shaped infundibulum moves so that its opening is adjacent to the site where the follicle ruptures
the ovum moves down the tube propelled by gentle peristalsis and currents created by the cilliated epithelium
secretory cells in the epithelium secrete nutrients
fertilization occurs in the ampulla and the fertilized ovum is then transported to the uterus for implantation
histology features of ampulla of uterine tubes?
mucosa is highly folded and lined by simple columnar epithelium with ciliated cells and secretory cells
- surrounded by 2 layers of smooth muscle
histology features of isthmus of uterine tube?
much simpler architechture of the tube lining
lining epithelium is mostly secretory with few cilliated cells
3 layers of smooth muscle
what makes up the uterine wall?
inner secretory mucosa made up of tubular secretory glands embedded in connective tissue = endometrium
3 layers of smooth muscle combined with collagen and elastic tissue = myometrium
outer vesicular covering of loose connective tissue covered by mesothelium = perimetrium
2 divisions of the endometrium?
stratum functionalis
- undergoes monthly growth, degeneration and loss
stratum basalis
- reserve tissue that regenerates the functionalis
what happens in the endometrium during the proliferative phase?
stratum basalis proliferates and glands, stroma and vasculature grow which reconstitutes stratum functionalis
occurs due to osterogen
how long does proliferative phase last?
until around 1 day after ovulation
what happens to glands as proliferative phase becomes secretory phase?
proliferative = glands are straight and lined with pseudostratified columnar epithelium secretory = glands become coiled and secrete glycogen
what happens in uterus in menstrual phase?
arterioles in the stratum functionalis undergo constriction which deprives the tissue of blood causing ischaemia
this results in tissue breakdown, leakage of blood and tissue sloughing
histological features of cervix?
mostly fibrous connective tissue covered by stratified squamous epithelium on its vaginal surface but transitioning to mucous secreting simple columnar epithelium
which is the most common site of dysplasia and neoplastic change in the cervix?
transition zone between stratified squamous and mucous secreting simple columnar epithelium
what are the endocervical glands and what do they secrete?
glands formed by furrowing of mucous secreting epithelium of cervix
secretions
- thin and watery in proliferative phase (allows passage of sperm)
- thick following ovulation (prevents passage of sperm and microbes)
what is a nabothian cyst?
expansion of endocervical glands due to blockage of the outlet of the gland
4 layers of the vagina?
- non-keratinised stratified squamous epithelium (thicker during reproductive years and cells are enlarged due to glycogen accumulation)
- lamina propria (connective tissue rich in elastic fibres and thin walled blood vessels)
- fibromuscular layer (inner circular and outer longitudinal smooth muscle)
- adventita
what glands are found in the vagina?
no glands
lubricated by mucous from the cervical glands and fluid from the thin walled vessels of the lamina propria
what protects the vagina from bacteria colonisation?
commensal bacteria metabolise the glycogen to lactic acid which inhibits growth of pathogenic bacteria
what is the mons pubis?
skin which contains highly oblique hair follicles (coarse, curly hair growth) overlying a substantial subcutaneous fat pad which itself overlies the pubic symphysis
what is 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
hair follicles on the outer surface but not the inner
what is the labia minora?
skin folds that lack subcutaneous fat and hair follicles
rich in vasculature and sebaceous glands which secrete onto skin surface
what is the clitoris?
contains two tubes of erectile vascular tissue (corpora cavernosa)
covered by a fibrocollagenous sheath covered by skin with rich innervation and a thin epidermis
