Reproduction - female anatomy/oogenesis/folliculogenesis

Question 1

What produces gametes in a female reproductive tract?

Answer 1

Ovary

Question 2

What is the anatomy of the ovary?

Answer 2

Outer layer - germinal epithelium
Connective tissues - tunica albuginea
Maturing follicles - cortex
Medulla - dense connective tissue with vasculature, lymphatics and nerves

Question 3

What happens in the oviducts?

Answer 3

They capture the oocyte and transfer it, as well as aid sperm in the ascent.

made of three sections:
Infundibulum
Ampulla
Isthmus

Question 4

What happens in the infundibulum?

Answer 4

Attached to ovary, has fimbriae to capture the oocyte

Question 5

What happens in the ampulla?

Answer 5

It’s wider, with fern like projections of ciliated epithelium. Fertilisation usually occurs here at the ampulla isthmus junction

Question 6

What happens at the isthmus?

Answer 6

A narrower region that meets the uterine horn with a thicker muscular wall and few mucosal folds.

Question 7

What is the uterus?

Answer 7

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

Question 8

What are the three layers of the uterus?

Answer 8

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

Question 9

What is the cervix?

Answer 9

Between the uterus and the vagina.

A transport for sperm but also acts as a sperm and bacteria barrier.

Question 10

What is the vagina?

Answer 10

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.

Question 11

What is the broad ligament?

Answer 11

Bilateral sheets, that anchor the uterus to the pelvic bones.
Made up of three areas:
-Mesometrium - supports uterus
-Mesoalphinx - supports oviduct
-Mesooovarium - supports ovary

Question 12

What is the round ligamet?

Answer 12

A lateral fold, from uterus down inguinal canal

Question 13

What is the inter-cornual ligament?

Answer 13

Holds two uterine horns together

Question 14

What is the suspensory ligament?

Answer 14

Periotoneal fold that attaches the ovaries to the abdominal wall at the last rib, extending to the kidney.

Question 15

What are the arteries of the female reproductive tract?

Answer 15

Ovarian artery
Uterine artery
Vaginal artery

Question 16

What does the ovarian artery originate from?

Answer 16

Branches off the aorta and the uterine branch

Question 17

What does the uterine artery originate from?

Answer 17

Internal illiac

Mare is the external iliac

Question 18

What does the vaginal artery originate from?

Answer 18

Branches off the iliac

Question 19

What veins are around the female reproductive tract?

Answer 19

Ovarian, uterine and vaginal vein

Question 20

What lymphatics are around the tract?

Answer 20

Drains into the aortic and sacral-iliac lymph nodes

Question 21

What innervates the tract?

Answer 21

Ovary - vagus (para) and intermesenteric and caudal mesenteric plexus (symp)

Vulva - motor nerves

Question 22

What are the three types of oestrus cycle?

Answer 22

Polyoestrus
Seasonal polyoestrus
Monoestrus

Question 23

What is (seasonal) polyoestrus?

Answer 23

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

Question 24

What is monoestrus?

Answer 24

Once a year

e.g. bears, dogs (3x in 2 years), wolves and foxes

Question 25

How is the oestrus cycle defined by the secretory products ?

Answer 25

Follicular phase (oestrogen dominant)

Ovulation/luteal phase (progesterone dominant)

Question 26

What is the signs of the follicular phase?

Answer 26

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

Question 27

What are the signs of the ovulation and luteal phase?

Answer 27

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

Question 28

How is the oestrus cycle defined by vaginal cytology ?

Answer 28

Pro-oestrus -oestrogen dominant
Oestrus - oestrogen dominant, LH surge
Meoestrus - transition to progesterone dominant
Dioestrus - progestrone dominant

Question 29

How is the oestrus cycle defined by the changes in endometrium cytology ?

Answer 29

Proliferative stage - oestrogen dominant and builds up endometrium

Secretory stage - progesterone dominant

Question 30

What is the hypothalamic-pituitary-gonadal axis?

Answer 30

1. Hypothalamus secretes GnRH
2. GnRH acts on anterior pituitary
3. 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
4. Oestradiol has a negative feedback on AP and hypothalamus until reaches the threshold.

Question 31

What is the two cell GnRH theory?

Answer 31

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.

Question 32

What is folliculogenesis ?

Answer 32

The recruitment and development of a follicle which contains an ovum

Question 33

What is the reserve of the follicle?

Answer 33

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.

Question 34

What occurs in the pre-antral stage?

Answer 34

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

Question 35

What occurs in the antral stage?

Answer 35

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

Question 36

What is the corpus luteum?

Answer 36

The left over lutenized cells after ovulation.

Question 37

What does the corpus luteum do?

Answer 37

It secretes progesterone, which supplies negative feedback on the hypothalamus to stop a further cycle

Question 38

How is progesterone produced by the CL?

Answer 38

Via cholesterol esters in the mitochondrial, by removing 6 carbons creating pregnenoline and eventually progesterone.

Question 39

How does the corpus luteum luteolyse?

Answer 39

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.

Question 40

What is the corpus haemorhaggium?

Answer 40

The dead CL becomes vascularied and the amount of lipid droplets and luteal pigments increase.