endocrinology of pregnancy Flashcards
What induces the reabsorption of the tubular fluid?
oestrogen
Recall seminiferous tubule details.
sertoli, ledig etc. (update this)
What induces nutrient secretion into epididymal fluid?
(e.g. fructose and glycoproteins)
androgens
Outline the components of the semen and the relative number of spermatozoa.
Spermatozoa - 15-120 millions
Seminal fluid
Leucocytes
(potentially viruses)
What proportion of sperm in ejaculate reach the ovum?
1/1million
What glands contribute to the formation of the seminal fluid?
Small contribution from epididymis/testis.
Main contribution from accessory sex glands:
- Seminal vesicles
- Prostate
- Bulbourethral glands
What is the seminal fluid?
the fluid the spermatozoa travel in
Label spermatozoan
What is the name for the changes sperm undergo to achieve fertilising capabvility in the female reproductive tract?
capacitation.
What are the characteristic processes of capacitation?
- Loss of glycoprotein ‘coat’
- Change in surface membrane characteristics
- Develop whiplash movements of tail
What mediates the process of capacitation?
- The ionic & proteolytic environment of the Fallopian tube
- Oestrogen-dependent
- Ca2+-dependent
What are the stages of the acrosome reaction?
•Sperm binds to ZP3
(= sperm receptor)
•Ca2+influx into sperm
(stimulated by progesterone)
•Release of hyaluronidase & proteolytic enzymes
(from acrosome)
–> penetration of zona pellicuda.
Label diagram of ovum at time of acrosome reaction.
Label diagram showing 3 stages of fertilisation.
What does fertilisation trigger? What does this do?
Cortical reaction.
- Cortical granules release molecules which degrade Zona Pellucida (e.g. ZP2 & 3)
- Therefore prevents further sperm binding as no receptors
outline the development of the conceptus.
- Continues to divide as it moves down Fallopian tube to uterus (3-4 days)
- Receives nutrients from uterine secretions
- This free-living phase can last for ~ 9-10 days
What are the two phases of implantation. Explain them. What hormone is needed.
•Attachment phase: outer trophoblast cells contact uterine surface epithelium
THEN
- Decidualisationphase :changes in underlying uterine stromal tissue (within a few hours)
- Requires progesteronedomination in the presence of oestrogen
Label diagram explaining blastocyst implantation.
What regulators are involved in embryo attachment?
- Leukaemiainhibitory factor (LIF)from endometrial secretory glands (& blastocyst?) stimulates adhesion of blastocyst to endometrial cells
- Interleukin-11 (IL11) also from endometrial cells is released into uterine fluid, and may be involved
- Many other molecules involved in process (e.g. HB-EGF)
What endometrial changes due to progesterone occur? What factors are involved?
- Glandular epithelial secretion
- Glycogen accumulation in stromal cell cytoplasm
- Growth of capillaries
- Increased vascular permeability (→oedema)
- Factors involved:
- Interleukin-11 (IL11), histamine, certain prostaglandins & TGFb(TGFbpromotes angiogenesis)
Label diagram showing hormone changes over time during pregnancy.
hCG, oestrogens, lactogen, progesterone.
Where are progesterone and oestrogen synthesised in the first 40 days of pregnancy?
Corpus luteum (stimulated by hCG acting on LH receptors).
What is the role of oestrogen and progesterone in the first 40 days of pregnancy?
- Essential for developing fetoplacental unit
- Inhibits maternal LH & FSH (-ve feedback)
What secretes oestrogen and progesterone after the first 40 days of pregnancy?
placenta
What hormones increase/decrease in secretion during pregnancy (maternally)?
Increase:
ACTH
Adrenal steroids
Prolactin
IGF1 (stimulated by placental GH-variant)
Iodothyronines
PTH related peptides
Decrease:
Gonadotrophins
Pituitary GH
TSH
Briefly outline the role of oxytocin (3 things)?
Uterine contraction
Cervical dilation
Milk ejection
Label diagram of titty-hypothalamo-pituitary axis - control of prolactin and oxytocin.
