endocrinology of pregnancy

Question 1

What induces the reabsorption of the tubular fluid?

Answer 1

oestrogen

Question 2

Recall seminiferous tubule details.

Answer 2

sertoli, ledig etc. (update this)

Question 3

What induces nutrient secretion into epididymal fluid?

(e.g. fructose and glycoproteins)

Answer 3

androgens

Question 4

Outline the components of the semen and the relative number of spermatozoa.

Answer 4

Spermatozoa - 15-120 millions

Seminal fluid

Leucocytes

(potentially viruses)

Question 5

What proportion of sperm in ejaculate reach the ovum?

Answer 5

1/1million

Question 6

What glands contribute to the formation of the seminal fluid?

Answer 6

Small contribution from epididymis/testis.

Main contribution from accessory sex glands:

• Seminal vesicles
• Prostate
• Bulbourethral glands

Question 7

What is the seminal fluid?

Answer 7

the fluid the spermatozoa travel in

Question 8

Label spermatozoan

Answer 8

Question 9

What is the name for the changes sperm undergo to achieve fertilising capabvility in the female reproductive tract?

Answer 9

capacitation.

Question 10

What are the characteristic processes of capacitation?

Answer 10

1. Loss of glycoprotein ‘coat’
2. Change in surface membrane characteristics
3. Develop whiplash movements of tail

Question 11

What mediates the process of capacitation?

Answer 11

• The ionic & proteolytic environment of the Fallopian tube
• Oestrogen-dependent
• Ca2+-dependent

Question 12

What are the stages of the acrosome reaction?

Answer 12

•Sperm binds to ZP3

(= sperm receptor)

•Ca2+influx into sperm

(stimulated by progesterone)

•Release of hyaluronidase & proteolytic enzymes

(from acrosome)

–> penetration of zona pellicuda.

Question 13

Label diagram of ovum at time of acrosome reaction.

Answer 13

Question 14

Label diagram showing 3 stages of fertilisation.

Answer 14

Question 16

What does fertilisation trigger? What does this do?

Answer 16

Cortical reaction.

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

Question 17

outline the development of the conceptus.

Answer 17

• 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 18

What are the two phases of implantation. Explain them. What hormone is needed.

Answer 18

•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

Question 19

Label diagram explaining blastocyst implantation.

Answer 19

Question 20

What regulators are involved in embryo attachment?

Answer 20

• 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)

Question 21

What endometrial changes due to progesterone occur? What factors are involved?

Answer 21

• 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)

Question 22

Label diagram showing hormone changes over time during pregnancy.

hCG, oestrogens, lactogen, progesterone.

Answer 22

Question 23

Where are progesterone and oestrogen synthesised in the first 40 days of pregnancy?

Answer 23

Corpus luteum (stimulated by hCG acting on LH receptors).

Question 24

What is the role of oestrogen and progesterone in the first 40 days of pregnancy?

Answer 24

• Essential for developing fetoplacental unit
• Inhibits maternal LH & FSH (-ve feedback)

Question 25

What secretes oestrogen and progesterone after the first 40 days of pregnancy?

Answer 25

placenta

Question 26

What hormones increase/decrease in secretion during pregnancy (maternally)?

Answer 26

Increase:

ACTH

Adrenal steroids

Prolactin

IGF1 (stimulated by placental GH-variant)

Iodothyronines

PTH related peptides

Decrease:

Gonadotrophins

Pituitary GH

TSH

Question 27

Briefly outline the role of oxytocin (3 things)?

Answer 27

Uterine contraction

Cervical dilation

Milk ejection

Answer 28

Label diagram of titty-hypothalamo-pituitary axis - control of prolactin and oxytocin.