color pdf

BIMM118
Sex Steroids
• Female reproductive cycle
– Second (= Secretory) phase:
• Secretory phase constant (~ 14 days)
• LH-stimulated ruptured follicle develops
into Corpus luteum which secrets
Progesterone
• Progesterone (Pg) is responsible for the
secretory phase: endometrium becomes
suitable for implantation; mucus thickens
• Thermogenic effects of Pg =>
body temperature increase 0.5º C
• Without implantation: Pg secretion stops
=> menstuation is triggered
• With implantation: continued Pg production
which (via inhibition of LH and FSH prod.)
blocks further ovulation
• Chorion (“precursor” of placenta) secretes
human chorionic gonadotropin (HCG) which
maintains endometrium lining throughout
pregnancy (HCG -> see pregnancy test)