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Flashcards in Reproduction Deck (50)
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1

Up to what week of foetal development are humans indifferent?

Indifferent until week 7

2

What is the default gender pathway?

Female

3

What the factors involved in producing a male foetus?

SRY - transcription factor expressed by the Y chromosome
Androgens and AMH are important signals in males

4

Where do the primordial germ cells migrate to ?

migrate to the genital ridge

5

What is the flow of cells produced during oogenesis?

Primordial germ cell
Oogonia
Primary oocyte
Secondary oocyte
Mature oocyte

6

What is significant about meiosis and what is the purpose of producing polar bodies during oogenesis?

Discontinuous - primary oocytes are all ready and waiting before a foetus is born and the cells are arrested in
prophase I, and then by puberty the secondary oocytes are arrested in metaphase II until a sperm fertilises them
-finite number of egg cells - born with all the eggs we will ever have
- up to week 20 there is massive proliferation of oogonia but in the second half of pregnancy there is significant atresia
Help the egg to get rid of excess genetic material

7

What are the different stages of follicles?

Primordial follicle (formed in utero), primary follicle (pre-antral), secondary follicle (pre-antral), tertiary follicle (antral/graafian follicle)

8

When and why does the blood-testis barrier form?

Develops during puberty to protect the sperm from the immune system and controls what enters and exits the seminiferous tubules
Forms between the sertoli cells

9

What is the flow of cells produced during spermatogenesis?

Primordial germ cells
Prospermatogonia - at genital ridges
Spermatogonial stem cells
Primary spermatocytes
Secondary spermatocytes
Round spermatids
Elongated spermatids
Spermatozoa

10

What is the purpose of the centrioles in the sperm?

eggs don't have centrioles so these centrioles are essential for the first cell division

11

Why does the sperm shed its cytoplasm?

Sheds it to make them more streamline

12

What does LH stimulate in the male HPG axis?

leydig cells to produce androgens (testosterone)

13

What does LH stimulate in the female HPG axis?

Theca cells - androgens which are aromatised in the granulosa cells by aromatase to produce oestrogens

14

What does the corpus luteum produce?

Oestrogen and progesterone

15

What are the 3 main families of steroids?

Estrogens
Progestins
Androgens

16

What do high levels and low levels of oestrogen do to the HPG axis?

High levels stimulate the anterior pituitary to release FSH/LH
Low levels inhibit the hypothalamus and anterior pituitary from releasing GnRH and LH/FSH respectively

17

Define:
Normal menstrual cycle
Oligomenorrhoea
Amenhorrhoea

Normal menstrual cycle = bleed every 28 days (26-32days)
Oligomenorrhoea =<9 cycles in the last 12 months
Amenhorrhoea = no bleed in the last 6 months - before puberty = primary whereas periods stopping = secondary

18

Which phase varies and subsequently affects the length of a female menstrual cycle?

variations in the follicular phase length (pre-ovulatory phase)

19

What are some causes of amenorrhoea?

ALWAYS exclude pregnancy
Central causes: hypothalamic (low leptin, Kallman syndrome), pituitary (hyperprolactinaemia, tumour ) (Low FSH/LH) = suppresses the HPG axis
Ovarian causes: Turners (X -), premature ovarian failure (elevated FSH/LH- brain is functioning but ovaries are not)

20

What is polycystic ovary syndrome?

Commonest endocrine condition (>10% of pre-menopausal women)
Symptoms: hyperandrogenic, insulin resistance, PCO
Rotterdam criteria- diagnosis criteria requiring you to have 2 out of 3 symptoms:
1) poly cystic ovaries
2) hyperandrogenism
3) oligomenoorhoea (80%)

Other common symptoms
- hirsuitism (30%)- excess body hair due to high levels of androgens
- obesity (40%)
- infertility (30%)
Unknown aetiology

21

What are examples of male endocrine disorders?

Delayed puberty
Reduced libido
Gynaecomastia
Reduced shaving frequency
Reduced testicular volume
Infertility

22

What are the primary causes of gonadal failure?

High FSH, LH
Trauma, chemo, surgery, cryptochidism (testes fail to descend), infections/inflammation, genetic (Klinefelter's - sometimes not picked up until infertility clinic)

23

What are the secondary causes of gonadal failure?

Low FSH, LH
Hypothalamic disorders (Kallman), hyperprolactinaemia
Pituitary tumours, androgen abuse

24

What are some other endocrine disorders affecting reproduction?

Congenital adrenal hyperplasia (21-OHD)- decreased cortisol and aldosterone and increased testosterone

Androgen insensitivity syndrome - androgen receptor

25

What are the prerequisites for fertilisation?

Sperm and oocyte in ampulla in the correct state
- oocytes - 24 hours its completed meiosis I and has started meiosis II but is arrested in metaphase II
- Capacitation of the sperm = final maturation process which takes place in the female tract - only once this has occurred can it fertilise the ovum

26

How long can sperm remain in the female tract?

Sperm can remain there for about 5 days but the egg of only viable for about 24 hours so there is a relatively small window for fertilisation to take place

27

What happens when the sperm fuses with the egg?

Sperm fusions triggers calcium increase = releases meiotic block, block to polyspermy (egg has evolved special mechanisms to prevent more than one sperm fusing with the egg)
Fast reaction = membrane depolarisation
Slow reaction = cortical reaction

Only about 10-100 sperm actually reach the ampulla

28

What defines the end of fertilisation?

Male and female pronuclei migrate towards each other and combine forming a zygote nucleus
- then cleavage commences
- implantation occurs at around day 7

29

How many couples have infertility problems ?

1 in 6 couples
15% unexplained - could be due to minor problems in both partners

30

What female factors can be involved in infertility?

Ovulatory disorders, tubal damage (blocked fallopian tube), endometriosis, uterine abnormalities, implantation/growth/development