(endo) pregnancy Flashcards
(54 cards)
in males, what occurs in the efferent ducts in the reproductive tract?
tubular fluid reabsorption resulting in concentration of fluid, which helps w male fertility
(induced by oestrogen)
in males, what occurs in the epididymis in the reproductive tract?
secretion of nutrients (e.g. fructose) and glycoprotein into the epididymal fluid
(induced by androgens)
what are the implications of aromatase deficiency?
(very rare!)
= hirsutism, acne, deep voice, primary amenorrhoea, tall (as need E2 to close epiphyseal growth plates), osteoporosis, virilisation of fetus
why is the secretion of nutrients into the epididymal fluid important in men?
fructose = provides an energy source for sperm to make their journey through the female reproductive tract
glycoprotein = preotective coating for sperm as they enter a hostile environment
what are the components of semen?
1) spermatozoa (15-120 million)
2) seminal fluid (2-5ml)
3) leukocytes
4) potentially viruses e.g. hepatitis B, HIV
what are the contents of seminal fluid?
- fructose
- fibrinogen
- fibrinolytic enzymes
- citric acid
- bicarbonate
where is seminal fluid secreted from?
accessory sex glands
- seminal vesicles
- prostate gland
- bulbourethral gland
small contribution from
- testis/epididymis
what is sperm capacitation?
the process of achieving fertilising capability in the female reproductive tract
what is involved in the capacitation of sperm?
1) loss of glycoprotein coat
2) changes in surface membrane characteristics
3) development of whiplash movements of the tail
where does capacitation of sperm occur?
takes place ONLY in the ionic & proteolytic environment of the fallopian tubes
(i.e. nowhere else in the male reproductive tract/initial parts of the female reproductive tracts)
what is sperm capacitation dependent on?
1) oestrogen-dependent
2) Ca2+-dependent
how many chromososme are found in one sperm?
23 chromosomes
= haploid
what is the acrosome?
organelle within sperm containing enzymes
= can bind to the zona pellucida
what is the zona pellicida?
glycoprotein layer surrounding the plasma membrane of the oocyte
explain what happens in the acrosome reaction
1) sperm bind to the ZP3 receptor (‘sperm receptor’) of the zona pellucida
2) Ca2+ influx into the sperm (stimulated by progesterone)
3) release of hyaluronidase and proteolytic enzymes from the acrosome
= sperm penetrates the zona pellucida and enters the oocyte
which receptor does the sperm bind to on the oocyte?
ZP3 receptor of the zona pellucida
what stimulates the calcium influx into the sperm during the acrosome reaction?
progesterone
why are hyaluronidase and proteolytic enzymes released from the acrosome?
to break down polysaccharides in the zona pellucida
= to allow sperm to enter the oocyte to enable fertilisation & fusion of gametes
where does fertilisation occur?
within the ampulla of the fallopian tube
what does fertilisation subsequently trigger?
the cortical reaction
what is the cortical reaction?
following fertilisation (i.e. once the sperm enters the egg), cortical granules release molecules that degrade the zona pellucida (e.g. ZP2 & 3)
= to prevent polyspermy
where are cortical granules found and why are they important?
in the oocyte
= release molecules upon fertilisation to degrade the zona pellucida
= so no polyspermy w no available receptors
as the conceptus travels down the fallopian tube to the uterus, how does it receive its nutrition?
receives nutrients from uterine secretion
= during the 3-4 days it takes to travel from the fallopian tube to the uterus
what are the two phases of implantation?
1) attachment phase
2) decidualisation phase
