Reproduction - female anatomy/oogenesis/folliculogenesis Flashcards
What produces gametes in a female reproductive tract?
Ovary
What is the anatomy of the ovary?
Outer layer - germinal epithelium
Connective tissues - tunica albuginea
Maturing follicles - cortex
Medulla - dense connective tissue with vasculature, lymphatics and nerves
What happens in the oviducts?
They capture the oocyte and transfer it, as well as aid sperm in the ascent.
made of three sections:
Infundibulum
Ampulla
Isthmus
What happens in the infundibulum?
Attached to ovary, has fimbriae to capture the oocyte
What happens in the ampulla?
It’s wider, with fern like projections of ciliated epithelium. Fertilisation usually occurs here at the ampulla isthmus junction
What happens at the isthmus?
A narrower region that meets the uterine horn with a thicker muscular wall and few mucosal folds.
What is the uterus?
Made up of the body and the horns.
The horns attach the uterus to the oviduct.
The uterus is the site of:
-Sperm implantation of zygote and placental attachment
-Provides nutritional support
-Source hormones and prostaglandins
- Place of parturition
Made up of three layers
What are the three layers of the uterus?
Perimetrium - cellular layer supporting
Myometrium - muscular layer with inner circular and outer longitudinal. Thickens in secretory phase after ovulation.
Endometrium - mucosa and submucosa, that contains glands for PGF2a, blood vessels and lymphatics
What is the cervix?
Between the uterus and the vagina.
A transport for sperm but also acts as a sperm and bacteria barrier.
What is the vagina?
A copulatory organ.
Secretes lubricant and pheromones.
Site of urine explosure and the birth canal.
Columnar epithelium in anterior and stratified squamous in the posterior.
What is the broad ligament?
Bilateral sheets, that anchor the uterus to the pelvic bones.
Made up of three areas:
-Mesometrium - supports uterus
-Mesoalphinx - supports oviduct
-Mesooovarium - supports ovary
What is the round ligamet?
A lateral fold, from uterus down inguinal canal
What is the inter-cornual ligament?
Holds two uterine horns together
What is the suspensory ligament?
Periotoneal fold that attaches the ovaries to the abdominal wall at the last rib, extending to the kidney.
What are the arteries of the female reproductive tract?
Ovarian artery
Uterine artery
Vaginal artery
What does the ovarian artery originate from?
Branches off the aorta and the uterine branch
What does the uterine artery originate from?
Internal illiac
Mare is the external iliac
What does the vaginal artery originate from?
Branches off the iliac
What veins are around the female reproductive tract?
Ovarian, uterine and vaginal vein
What lymphatics are around the tract?
Drains into the aortic and sacral-iliac lymph nodes
What innervates the tract?
Ovary - vagus (para) and intermesenteric and caudal mesenteric plexus (symp)
Vulva - motor nerves
What are the three types of oestrus cycle?
Polyoestrus
Seasonal polyoestrus
Monoestrus
What is (seasonal) polyoestrus?
Cycle all year around, e.g. cows, cats, pigs and rodents
Seasonal polyoestrus - repeated cycles at points of the year e.g. ewes in autumn and mares in spring
What is monoestrus?
Once a year
e.g. bears, dogs (3x in 2 years), wolves and foxes
How is the oestrus cycle defined by the secretory products ?
Follicular phase (oestrogen dominant)
Ovulation/luteal phase (progesterone dominant)
What is the signs of the follicular phase?
Shorter in animals without menses (20% of cycle)
Decrease in oestradiol required and ovulation occurs at the end
Proliferative phase of uterine cycle, thickening and secretion of alkaline mucous
What are the signs of the ovulation and luteal phase?
End of the follicular phase, with CL and oocyte is viable for 24 hours after release
Thickened endometrium and myometrium. Thick acidic mucous forms to prevent polyspermy
Menses occurs in absence of fertilisation
How is the oestrus cycle defined by vaginal cytology ?
Pro-oestrus -oestrogen dominant
Oestrus - oestrogen dominant, LH surge
Meoestrus - transition to progesterone dominant
Dioestrus - progestrone dominant
How is the oestrus cycle defined by the changes in endometrium cytology ?
Proliferative stage - oestrogen dominant and builds up endometrium
Secretory stage - progesterone dominant
What is the hypothalamic-pituitary-gonadal axis?
- Hypothalamus secretes GnRH
- GnRH acts on anterior pituitary
- The anterior pituitary:
>LH - acts on Theca cells to produce androgens, which travel to granulosa cells
>FSH - acts on Granulosa cells, stimulating follicular growth and stimulating inhibin
4.The granulosa cell products oestradiol - Oestradiol has a negative feedback on AP and hypothalamus until reaches the threshold.
What is the two cell GnRH theory?
When LH binds the Theca cells, it activates enzymes to convert cholesterol into androgens.
These androgens travel to the granulosa cells, which are converted to oestrogen under the FSH influence.
What is folliculogenesis ?
The recruitment and development of a follicle which contains an ovum
What is the reserve of the follicle?
There is a reserve of follicles that exist in prophase I when the animal is born in meiotic arrest.
At the LH surge the follicles resume metaphase II and if required complete.
What occurs in the pre-antral stage?
It is GnRH dependent
Primordial
-arrested with a single layer of granulosa cells
Primary follicle
- single cuboidal layer of granulosa cells, forming the zona pellucida, right in GAGs.
-surrounding stroma cells become theca internal and externa
Secondary follicle
-fully grown with granulosa and theca cells, forming the theca folliculi that are responsive to LH
What occurs in the antral stage?
It is GnRH independent.
Antral
-An antrum is formed from fluid in the granulosa cells, stimulated by the FSH presence.
Pre-ovulatory/Graafian
-When FSH falls, more of the follicles become atretic. The dominant cells continue to grow and it takes 14 days.
Ovulatory
-The dominant cells develop LH receptors, which makes them responsive to the LH surge
-Slow puncture of the follicle allows the fimbra in the infundibulum to capture the egg stimulating it to complete meiosis I.
-No LH surge leads to it becoming atretic within 72 hours
What is the corpus luteum?
The left over lutenized cells after ovulation.
What does the corpus luteum do?
It secretes progesterone, which supplies negative feedback on the hypothalamus to stop a further cycle
How is progesterone produced by the CL?
Via cholesterol esters in the mitochondrial, by removing 6 carbons creating pregnenoline and eventually progesterone.
How does the corpus luteum luteolyse?
It produced oxytocin, which stimulates PGF2a secretion from the uterus.
This feedbacks on the CL and inhibits the production of progesterone and stimulates more oxytocin.
The decrease in progesterone removes the neg effect on the AP and hypothalamus, leading to an increase in FSH and another follicle is recruited.
What is the corpus haemorhaggium?
The dead CL becomes vascularied and the amount of lipid droplets and luteal pigments increase.
