Fertilisation

Question 1

What effect does parasympathetic and sympathetic stimulation have in sexual intercourse?

Answer 1

Point and shoot:

Parasympathtic - arousal
Sympathetic - Ejaculation

Question 2

Describe the process of fertilisation

Answer 2

1. Sperm swins into cervical canal due to flagellal movements and through uterus due to uterine contractions, stimulated by sperm prostaglandins
2. As it reaches the ampulla, sperm undergoes capacitation in anticipation of fertilisation- more vigorous flagellal beating, and cholesterol, glycoprotein and protein removal due to female secretions
3. Sperm penetrates corona radiata due to flagellal movements and through Zona Pellucida through ZP3 receptor (triggers release of acrosomal enzymes)
4. Buries through secondary oocyte cell membrane, fertilisingit
5. Secondary oocyte undergoes end of second meiotic division upon fertilisation, producing zygote

Question 3

What receptor on the secondary oocyte does the sperm bind to?

Answer 3

ZP3

Question 4

Explain the mechanisms which prevent polyspermy

Answer 4

Fast block - when sperm penetrates secondary oocyte membrane, it causes a chemical change due to calcium influx, resulting in cell membrane depolarisation

Slow block - cortical granules release serine proteases which degrade glycoprotein receptors on the zona pellucida

Question 5

What 3 layers must the sperm penetrate in fertilisation?

Answer 5

Corona radiata
zona pellucida
secondary oocyte membrane

Question 6

List 3 causes of female infertilty

Answer 6

1. Anovulation
2. Endometriosis
3. Polcystic ovarian syndrome

Question 7

List 3 causes of male infertility

Answer 7

1. Ejaculatory duct obstruction
2. Erectile dysfunction
3. Impaired sperm motility -(e.g. as in kartageners syndrome)

Question 8

List fertility tests

Answer 8

Semen analysis
Luteal-phase progesterone
urinary LH
Transvaginal ultrasound
Hysteroalpingogram