The Endocrinology of Pregnancy Flashcards
(38 cards)
What do Sertoli cells make?
Spermatozoa and oestrogen
What do Leydig cells produce?
Testosterone
Where are sertoli cells found?
In the seminiferous tubules within the testes
Give 3 symptoms of aromatase deficiency (thus oestrogen deficiency) in males and why they occur
- Infertile - oestrogen is important for tubular fluid reabsorption within the rete testis and early epididymis
- Osteoporosis - oestrogen plays a role in bone turnover
- Tall - oestrogen is needed to close the growth plates
What happens in aromatase deficiency that causes symptoms in females and give 3 specific symptoms that females experience
- Aromatase deficiency causes less conversion of testosterone into oestrogen in the steroid biosynthetic pathway so there is a defiency in oestrogen and a build-up of testosterone which both cause symptoms. Virilisation
- Hirsutism
- Deepening voice
- Amenorrhoea
Where and how is tubular fluid reabsorbed?
- In the rete testis and the early epididymis
- Induced by oestrogen
Where would you find oestrogen in the male reproductive system?
Mainly in tubular fluid produced by Sertoli cells
What secretions occur into the tubular fluid as it becomes the epididymal fluid (as it enters the epididymis), and what is the function of these secretions?
- Fructose - provide energy for the journey
- Glycoproteins - coat the surface of the spermatozoa (to protect them from the hostile environment)
What does semen consist of?
- Spermatozoa
- Seminal fluid
- Leucocytes
- Viruses possibly - Hep B, HIV etc
Why does the concentration of spermatozoa decrease further down the male reproductive tract from the vas deferens to the urethra?
Because you add fluid as you go
Where are the 3 main sites of seminal fluid production, and where are 2 other minor sites of seminal fluid production?
Main
- Prostate
- Bulbourethral gland
- Seminal vesicles
Minor
- Testes
- Epididymis
How is seminal fluid concentrated, and what hormone induces this?
Concentrated by tubular fluid reabsorption as induced by oestrogen
1) What is the principle of the need for capacitation of sperm?
2) In what environment and where does sperm capacitation take place?
3) What 2 things is sperm capacitation dependent upon?
4) Give 3 things that happen to sperm in sperm capacitation
1)
- Sperm is quiescent within the seminferous tubules and has limited movement and capability within the vas deferens. Sperm capacitation is the activation of the full fertilising capability of the sperm within the female reproductive tract
2)
- Within the ionic and proteolytic environment of the female reproductive tract
3)
- Oestrogen-dependent
- Ca2+ dependent
4)
- Lose their glycoprotein coat
- Change in the surface membrane characteristics
- Develop whiplash movements of their tails
Describe the acrosome reaction for fertilisation
- Spermatozoon acrosome binds ZP3 glycoprotein receptor on oocyte
- Ovum secretes progesterone which stimulates Ca2+ influx into spermatozoon
- Simultaneous secretion of both proteolytic enzymes and hyaluronidase (polsaccharide enzyme) to break down the zona pellucida glycoprotein layer surrounding the oocyte
How does one spermatozoon prevent another binding to the same oocyte during fertilisation?
Once one spermatozoon binds an oocyte, it triggers a cortical reaction in the zona pellucida that blocks more sperm binding - cortical granules release molecules that degrade the ZP2/3 receptors on the zona pellucida of the oocyte to prevent another spermatozoon binding
How is a second polar body formed in the female oocyte maturation pathway?
There is an even mieotic division of chromosomes at one point, but uneven cytoplasm distribution - generating one viable oocyte with lots of cytoplasm and a second polar body with insufficient cytoplasm which gets degraded
1) What is the free-living phase of fertilised eggs, and how does it last?
2) What actual phase during menstruation does this free-living phase occur and so what hormones are high in concentration at this time?
1)
- The phase wherein the fertilised egg migrates from the fallopian tube down to the uterus, all the while developing and receiving nutrients from uterine secretions, prior to endometrial attachment
- Lasts for 9-10 days
2)
- During the luteal phase
- Oestrogen and progesterone
1) Outline the development process of the conceptus / zygote during the free-living phase including…
2) …What promotes the transfer to the uterus?
1)
- Fertilised egg divides to form 2-cell compactus
- 2-cell divides again and again and possibly again until you have an 8 or 16-cell compactus
- This undergoes compaction to form a morula
- This eventually develops into a blastocyst with an inner cell mass which becomes the embryo, a blastocystic cavity and outer trophoblast cells which becomes the chorion and thence the placenta
2)
- The high progesterone:oestrogen ratio that occurs in the luteal phase promotes transfer of the developing zygote to the uterus
What are the 2 phases of endometrial implantation of the zygote?
- Attachment
- Decidualisation
1) What essentially happens in the attachment phase of implantation?
2) What 2 substances are important in the attachment phase, where are they secreted from / into (where applicable) and what stimulates their release?
1)
- Outer trophoblast cells of the blastocyst attach to the uterine surface epithelium - endometrium
2)
- Leukemia Inhibitory Factor (LIF) - secreted from endometrial cells, stimulated by TGF, TNF, IL-1, Hb-EGF, Leptin, Progesterone
- IL-11 - released from endometrial cells, released into uterine fluid, stimulated by TGF, TNF, IL-1, Relaxin, PGE2
1) What happens in the decidualisation reactions of endometrial implantation?
2) What factors are involved in these?
1)
- Glandular epithelial secretion of nutrients
- Glycogen accumulation in stromal cell cytoplasm (under epithelium)
- Capillary growth (to improve blood supply)
- Increased vascular permeability (→oedema)
2)
- IL-11
- Histamine
- Certain prostaglandins
- TGF-ß (promotes angiogenesis)
What are the main 4 hormone changes that are noticeable during pregnancy at first?
- At first there is a rise in hCG
- Rise in oestrogen
- Rise in progesterone
- Rise in human placental lactogen
What happens to progesterone and oestrogen production, and what is the role of hCG…
1) In the first 40 days of pregnancy?
2) After the first 40 days of pregnancy?
1)
- Corpus luteum secretes oestrogen and progesterone
- This is stimulated by hCG acting on LH receptors
- hCG also prevents the increased oestrogen from having loads of negative inhibition on the LH / FSH
2)
- Placenta takes over oestrogen and progesterone production
- Not driven by hCG / LH / FSH
Label this diagram of the foeto-placental hormone axis
