Repro

Question 1

Describe oogenesis

Answer 1

1. The formation of gametes in the ovaries.
2. Starts in utero, in developing fetus
3. Primordial germ cells migrate from the yolk sac to the ovaries where they differentiate into oogonia

Question 2

What are Oogonia?

What is a germ cell

Answer 2

1. Diploid stem cells that divide mitotically to produce millions of germ cells
2. Cell containing half the number of chromosomes of a somatic cell and able to unite with one from the opposite sex to form a new individual; a gamete.

Question 3

What happens to oogonia produced in early fetal development before birth

Answer 3

1. most degenerate and die
2. few develop into primary oocytes (immature egg) before birth
3. these enter first phase of mitotic division Prophase 1
4. Don’t complete this until after puberty
5. These can be found in primordial follicles
6. female germ cells produce a primordial germ cell (PGC), which then undergoes mitosis–> oogonia –> oogenisis –> primary oocytes –> prophase

Question 4

Development of what 2 things occurs at the same time?

Answer 4

1. follicle

2. gamete

Question 5

What happens at puberty?

Answer 5

1. Several primordial follicles will be stimulated each month
2. Follicles develop from primary to sec to tertiary follicle
3. Oocytes develop from primary to secondary

Question 6

What happens at point of ovulation?

Answer 6

1. Tertiary follicle ruptures to expel secondary oocyte into pelvic cavity, normally to be swept into fallopian tube
2. At ovulation secondary oocyte will complete meiosis 1

Question 7

What is Corpus Luteum?

Answer 7

1. In ovary the mature tertiary follicle (Graafian) becomes CL
2. It is formed in an ovary at the site of a follicle, or sac, that has matured and released its egg
3. Temporary structure essential for establishing and maintaining pregnancy in females as secretes progesterone
4. if sec oocyte not fertilised CL stops secreting progesterone and degenerates into corpus albicans

Question 8

What does the pituitary gland look like?

Answer 8

1. Cherry red circle ventral aspect of brain

2. Protrusion off the bottom of the hypothalamus at base of brain

Question 9

Outline the development of the pituitary

Answer 9

1. Comprises 3 different structures: Anterior pituitary, intermediate lobe, Posterior pituitary
2. AP and IL derived from upgrowth extension endoderm of buccal cavity
3. PP derived from neural ectoderm, downgrowth extension of hypothalamus
4. Pituitary is 2 fused glands
5. IL developmentally is same as AP but is distinct anatomic area with distinct function. Releases MSH (melanin, skin pigment produced)

Question 10

Posterior pituitary does not …….

Answer 10

NOT sysnthesise anything

It releases substances that are synthesised in neuroendocrine cells in the hypothalamus

Question 11

What do neuro endocrine cells in the hypothalamus do to the anterior pituitary

Answer 11

1. act on AP, which releases tropic hormones = released into general circulation into another endocrine gland = amplify signal

Question 12

What hormones does the anterior pituitary secrete?

Answer 12

FLAT PIG
1. FSH = follicle stimulating hormone (testes and ovary)
2. LH = (T and O) = leutinising hormone. triggers ovulation and development of the corpus luteum
3. ACTH = Adreno corteco tropic hormone
4. TSH = thyroid stimulating hormone
5. GH = growth hormone
6. Prolactin (mammary gladns)
——————————-
Exception of prolactin, everything else affects another endocrine gladn

Question 13

Difference between long adn short feedback

Answer 13

1. Short = hormones act back into system nearest to them e.g. release of pituitary hormone affects hypothalamus

Question 14

Where is ADH synthesised?

Answer 14

HYPOTHALAMUS

Question 15

What day is day 0 and why?

Answer 15

1. the first day of menstrus

2. straight forward reference point

Question 16

With regards to ovulation what hormones are we talking about and where from?

Answer 16

1. GnRH from hypothalamus
2. FSH and LH from AP
3. Ostrogens and progesterone and inhibin from ovary

Question 17

What does GnRH cause

Answer 17

1. release of FSH and LH from pituitary whihc affects gonads
2. FSH stimulates the growth and recruitment of immature ovarian follicles
3. LH = variety - productions of precursors of oestrogen, stimulates maturation of ovarian follicles, triggers ovulation and development of the corpus luteum

Question 18

What role does hypothalamus have on AP

Answer 18

1. regulated output from AP

2. BRAIN CONTROLS REPRODUCTION

Question 19

If there was a graph showing peaks of GnRH production, where would the peaks of LH and FSH be?

Answer 19

1. FSH peak little behind GnRH and little lower
2. LH on/ little behind FSH peak and huge peak
   LH and FSH released from pituitary at same time but FSH = longer half life therefore diff shape

Question 20

Talk through from hypothalamus to the 3 hormones released

Answer 20

1. hypothalamus secretes GnRH
2. AP secretes FSH and LH
3. FSH acts of developing follicles, releasing inhibin and oestrogen
4. LH acts of corpus luteum releasing progesterone AND on dev follicles releasing inhibin and oestrogen

Question 21

What type of endocrone gland are both follicles and corpus luteum

Answer 21

1. TRANSIENT (come and go away)

2. So ovary (apart from housing female gamete) is a collection of transient endocrine glands

Question 22

What negative feedback effects does progesterone, inhibin and oestrogen have?

Answer 22

1. Progesterone ALWAYS neg feedback = inhibits GnRH release and LH
2. Inhibin neg feedback on FSH
3. Oestrogen usually neg feedback on LH and GnRH and FSH

Question 23

What is the follicular phase?

Answer 23

1. first 2 weeks of human menstral = follicles developing before ovulate

Question 24

What is the end of the follicular phase?

Answer 24

1. positive feedback
2. oestrogen starts producing more GnRH = more LH, FSH inhibited by inhibin
3. more and more LH = inc maturation of follicle and inc precursors of oestrogen = more and more = positive feedback
4. this continues until LH surge = ovulation

Question 25

Important changes in hormones to remmeber

Answer 25

1. LH surge JUST before ovulation always as it causes it 2. first half of cycle = inc oestrogen as this drives LH surge, peak close and before LH surge 3. same peak of oestrogen = little peak in FSH as huge inc in GnRH 4. Progesterone rise AFTER ovulation -------------------------------- This occurs due to neg and pos feedback occurring at pituitary and hypothalamus