endocrinology of pregnancy

Question 1

what is tubular fluid reabsorption induced by?

Answer 1

oestrogen

Question 2

Nutrients (eg fructose) & glycoprotein secretion into epididymal fluid
are induced by ?

Answer 2

androgens

Question 3

what does the semen contain?

Answer 3

Spermatozoa 15-120 million/ml

Seminal fluid 2-5ml

Leucocytes
(potentially viruses e.g. hepatitis B, HIV)

Question 4

what produces the seminal fluid?

Answer 4

Small contribution from:
Epididymis/testis

Mainly from accessory sex glands:

Question 5

what are the accessory sex glands?

Answer 5

Seminal vesicles
Prostate
Bulbourethral glands

Question 6

what happens during capacitation?/

Answer 6

Achieve fertilising capability in the female repro tract

Loss of glycoprotein ‘coat’
Change in surface membrane characteristics
Develop whiplash movements of tail

Question 7

where does capacitation take place and what does it require?

Answer 7

Takes place in ionic & proteolytic environment of the Fallopian tube
Oestrogen-dependent
Ca2+-dependent

Question 8

what happens in the acrosome reaction?

Answer 8

Sperm binds to ZP3 
(= sperm receptor)
Ca2+ influx into sperm 
(stimulated by progesterone)
Release of hyaluronidase & proteolytic enzymes 
(from acrosome)

Spermatozoon penetrates the Zona Pellucida

Question 9

where does fertilisation occur?

Answer 9

fallopian tube

Question 10

what reaction does fertilisation also occur and describe this reaction?

Answer 10

Triggers cortical reaction
Cortical granules release molecules which degrade Zona Pellucida (e.g. ZP2 & 3)
Therefore prevents further sperm binding as no receptors

Question 11

what happens to the conceptus right after fertilisation?

where does it receive nutrients from?

how long can this last for?

Answer 11

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

Question 12

describe the two phases of implantation

Answer 12

Attachment phase: outer trophoblast cells contact uterine surface epithelium

THEN

Decidualisation phase : changes in underlying uterine stromal tissue (within a few hours)

Question 13

what does the decidualisation phase require?

Answer 13

Requires progesterone domination in the presence of oestrogen

Question 14

what molecules does the attachment phase need?

Answer 14

Leukaemia inhibitory 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)

Question 15

describe the endometrial changes in decidualisation = what is it due to?

What are the factors involved?

Answer 15

Endometrial changes due to progesterone

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 (TGFb promotes angiogenesis)

Question 16

describe the progesterone and oestrogen production patterns during pregnancy

Answer 16

First 40 days
Produced in corpus luteum (in maternal ovary)
stimulated by hCG (produced by trophoblasts) which acts on LH receptors
Essential for developing fetoplacental unit
Inhibits maternal LH & FSH (-ve feedback)

From day 40
Placenta starts to take over

Question 17

what molecule do the mother and fetus both produce?

Answer 17

DHEAS

which can then go onto producing oestradiol and oestrone

Question 18

what hormones increase in pregnancy?

Answer 18

ACTH
Adrenal steroids
Prolactin
IGF1 (stimulated by placental GH-variant)
Iodothyronines
PTH related peptides

Question 19

what hormones decrease in pregnancy?

Answer 19

Gonadotrophins
Pituitary GH
TSH

Question 20

what does oxytocin do?

Answer 20

Uterine contraction
Cervical dilation
Milk ejection

Question 21

what is prolactin for?

Answer 21

milk synthesis