Flashcards in Reproduction and Endocrine Deck (73)
What is oogenesis?
The formation of gametes in the ovaries
How are oogonia developed?
In foetal development, primordial cells migrate from yolk sax to ovaries where they differentiate into oogonia
What do some oogonia develop into?
Primary oocytes and enter prophase of meiosis 1
What happens at puberty?
Several primordial follicles stimulated each month, follicles develop to tertiary follicle, and oocytes to secondary oocyte
How many chromosomes does a secondary oocyte have?
What occurs at ovulation?
tertiary follicle ruptures to expel secondary oocyte
When does the second meiotic occur?
What happens to the follicle after it ruptures?
It becomes a corpus luteum
What happens to a corpus luteum if secondary oocyte not fertilised?
After 14 days undergoes luteolysis, stops secreting progesterone and becomes corpus albicans
How is the anterior and posterior developed?
Anterior- made from endocrine cells from rathkes pouch which wraps around the posterior
Posterior- Extension of hypothalamus into anterior
What controls the release of anterior pituitary hormones?
Neurohormones from hypothalamus via a portal system
What kind of hormones does hypothalamus release which causes anterior to produce what hormones?
Hypothalamus- releasing hormone
Anterior- trophic hormone
What 6 hormones does the anterior pituitary secrete?
What is multi-loop feedback in hypothalamus and anterior pituitary?
There is a short loop and long loop, which tropic inhibits releasing as well as hormone
What is the structure between anterior and posterior pituitary called?
Where is GnRH released from?
What does GnRH cause the release of?
FSH and LH
What does FSH do?
stimulates growth and recruitment of mature follicles
What are the functions of LH?
Produces precursors for oestrogen production
Maintains corpus luteum
Stimulates- maturation, ovulation, luteinisation
What do developing follicles and corpus luteum produce after stimulation from FSH and LH?
Why are developing follicles and corpus luteums transient endocrine glands?
They come and go
What does progesterone inhibit?
LH and GnRH
What does oestrogen start by inhibiting?
LH and GnRH
What does inhibin inhibit?
Why does oestrogen change to positive feedback?
The sensitivity of brain changes in the late follicular phase
What is a dominant follicle?
A tertiary follicle that produces lots of oestrogen preventing other follicles maturing
What happens after the follicular phase?
Oestrogen causes GnRH which causes LH to produce (FSH inhibited by inhibin) increasing oestrogen and so on until ovulation
What causes ovulation?
An LH surge from positive feedback
What follows the follicular phase?