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Loss and Renewal > Reproduction > Flashcards

Reproduction Flashcards

1
Q

Up to what week of foetal development are humans indifferent?

A

Indifferent until week 7

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2
Q

What is the default gender pathway?

A

Female

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3
Q

What the factors involved in producing a male foetus?

A

SRY - transcription factor expressed by the Y chromosome

Androgens and AMH are important signals in males

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4
Q

Where do the primordial germ cells migrate to ?

A

migrate to the genital ridge

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5
Q

What is the flow of cells produced during oogenesis?

A 
Primordial germ cell
Oogonia
Primary oocyte
Secondary oocyte
Mature oocyte
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6
Q

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

A

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

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7
Q

What are the different stages of follicles?

A

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

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8
Q

When and why does the blood-testis barrier form?

A

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

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9
Q

What is the flow of cells produced during spermatogenesis?

A 
Primordial germ cells 
Prospermatogonia - at genital ridges
Spermatogonial stem cells 
Primary spermatocytes 
Secondary spermatocytes 
Round spermatids 
Elongated spermatids 
Spermatozoa
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10
Q

What is the purpose of the centrioles in the sperm?

A

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

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11
Q

Why does the sperm shed its cytoplasm?

A

Sheds it to make them more streamline

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12
Q

What does LH stimulate in the male HPG axis?

A

leydig cells to produce androgens (testosterone)

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13
Q

What does LH stimulate in the female HPG axis?

A

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

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14
Q

What does the corpus luteum produce?

A

Oestrogen and progesterone

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15
Q

What are the 3 main families of steroids?

A

Estrogens
Progestins
Androgens

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16
Q

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

A

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

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17
Q

Define:
Normal menstrual cycle
Oligomenorrhoea
Amenhorrhoea

A

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

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18
Q

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

A

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

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19
Q

What are some causes of amenorrhoea?

A

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)

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20
Q

What is polycystic ovary syndrome?

A

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
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21
Q

What are examples of male endocrine disorders?

A 
Delayed puberty 
Reduced libido 
Gynaecomastia 
Reduced shaving frequency 
Reduced testicular volume 
Infertility
22
Q

What are the primary causes of gonadal failure?

A

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

23
Q

What are the secondary causes of gonadal failure?

A

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

24
Q

What are some other endocrine disorders affecting reproduction?

A

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

Androgen insensitivity syndrome - androgen receptor

25
Q

What are the prerequisites for fertilisation?

A

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
Q

How long can sperm remain in the female tract?

A

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
Q

What happens when the sperm fuses with the egg?

A

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
Q

What defines the end of fertilisation?

A

Male and female pronuclei migrate towards each other and combine forming a zygote nucleus

  • then cleavage commences
  • implantation occurs at around day 7
29
Q

How many couples have infertility problems ?

A

1 in 6 couples

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

30
Q

What female factors can be involved in infertility?

A

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

31
Q

What male factors can be involved in infertility?

A

Sperm production, sperm transmission, sperm transport (many are not capable of traversing the female tract), fertilisation and development

32
Q

What diagnostic procedures are available to determine infertility?

A

Blood tests - endocrinology - FSH/LH/Progesterone
Hysterosalpinogram, laparoscopy
Semen analysis: normozoospermic, oligozoospermic (too few sperm), asthenozoospermic (low motility), tetratozoospermic (abnormal morphology), azoospermic (no sperm)

33
Q

What treatment approaches are their available for infertility?

A

Ovulation induction - estrogen inhibitor to induce ovulation
IUI - interuterine insemination - directly inserting sperm into the uterus - the timing is key
IVF
ICSI - intracytoplasmic sperm injection
Ovarian stimulation = IVF and ICSI - stimulate a women to produce about 10-15 eggs a month
Donor gametes/embryo

34
Q

What are the types of contraception?

A

Hormonal - COC, POP, patch, implant, injection, ring
Barrier - Condoms, diaphragm, cap, spermicides
IUD/IUS (cu coil, mirena)
Sterilisation
Natural methods
Emergency contraception
Termination of pregnancy

LARCs = long acting reversible contraceptives e.g. implant, coil, injection

35
Q

What is the first hormone produced during pregnancy?

A

hCG - developing embryo (it enables survival of the corpus luteum)

36
Q

What are the key factors involved in parturition?

A

Increased oestrogen:progesterone stimulates contraction
Fetal corticosteroid release stimulates oestrogen and prostaglandin synthesis (cervical softening and dilation, muscle contraction)
Ferguson reflex (release of oxytocin in response to pressure on cervix, +ve feedback, prostaglandin release)
Relaxin - pelvic ligaments and softens cervix

37
Q

What hormones are involved in stimulating the development of breast tissue?

A

Oestrogen, progesterone, hPL and prolactin

38
Q

What inhibits milk secretion during pregnancy?

A

Steroid hormones and hPL inhibit milk secretion

39
Q

What is the letdown reflex?

A

Prolactin causes milk synthesis, stimulation of the nipple causes oxytocin release to trigger milk ejection and continued prolactin production
Prolactin release inhibits FSH and LH - lactational amenorrhoea

40
Q

What physiological changes occur in the mother during pregnancy?

A

Cardiovascular adaptations - cardiac functioning and haemodynamic changes
Placenta - development and structure, transport, immune privilege
Regulation of uterine activity: myometrium - suppressed during pregnancy but switched at birth

41
Q

What are some examples of different screening tests during pregnancy?

A

urine dipstick, USS, combined test/triple/quad test, nuchal translucency, ffDNA

42
Q

What other tests can be looked into during pregnancy?

A

Genetic tests (pedigrees), ancestry

43
Q

What are some common complications during pregnancy?

A

Pre-eclampsia: characterised by onset of high blood pressure and high concentration of protein in urine
Gestational diabetes mellitus

44
Q

What are the definitive signs of puberty?

A 
Females: menarche
Males: first ejaculation 
other factors:
- growth spurts 
- Secondary sex characteristics - timings vary between individuals and be used for staging (Tanner)
45
Q

How are the female secondary sex characteristics developed?

A

Ovarian oestrogen leads to the development of breasts and genitalia
Ovarian and adrenal androgens leads to the development of pubic and axillary hair

46
Q

How are the male secondary sex characteristics developed?

A

Testicular androgens leads to public and axillary hair growth, genitalia, enlargement of larynx and laryngeal muscles

47
Q

Define: precocious puberty

A

onset of secondary sex characteristics before 8 years in girls and before 9 years in boys
- menarche before 9 years in girls is linked to short stature because the bone growth plate fuse early

48
Q

Define: delayed puberty

A

absence of secondary sex characteristics by 14 years in girls and 16 years in boys
- delayed puberty may lead to osteoporosis

49
Q

What is the suggested mechanism underlying puberty?

A

Hypothalamic maturation hypothesis - increased hypothalamic GnRH
Kisspeptin - GPR54
Leptin - body mass seems to be a key determinant for triggering puberty

50
Q

What does the human fertilisation and embryology authority (HFEA) do?

A 
Patient safety 
Welfare of children 
Policy making 
Embryo research 
Control over gametes and embryos

Loss and Renewal (6 decks)

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