Evolutionary Development Biology – Lecture 4 – Fertile or not?
Menstrual cycle
Female fertility is cyclic (28 days)– ovulation once a month – first cycle is menarche –
fertile period is 14 days before onset next cycle – conception risk highest 2-3 days
before ovulation
Maturation & release of egg
Preparation of uterus for fertilised egg
Male fertility is constant – survive 3-4 days in uterine tubes
Optimal fertility is between 20-30 years. Girls nowadays becomes sexually mature
women earlier becausee they are growing faster so reaching reproductive maturity at
earlier ages but their brains are not fully mature!
Menopause
Cessation (ophouden) of spontaneous menstruation:
Around 48-51 years because of exhausting (uitputting) of follicles in ovary.
FSH and LH are elevated (verhoogd)
Surgical menopause – oophorectomy is removal of ovaries
Temporary pharmacological menopause (pill) – GnRH in non-pulsatile form
Determination of normal menopause;
Genetics
Employment status
Divorcement status
Smoking – decrease length of normal cycle & shorter peri-menopause
duration (period before the menopause the menstruation is changing)
Menopause is associated with osteoporosis, diabetes, cardiovascular disease –
taking birth control pill may help in cases of perimenopausal symptoms
Birth control
Allows coupled to plan family size, allow women to become sexually independent,
can be used to prevent transmission of sexually transmitted diseases (STDs)
Two methods:
1. Rhythm method; avoid sex on peak of fertility
2. Contraception method – prevent ovulation
a. Barrier contraceptive (condom); limits the transmission of STDs
b. Intrauterine devices (IUDs) (spiraaltjes); do not prevent implantation but
sperm migration, ovum transport and fertilization
c. Pill use; mimics (nabootsen) conditions in luteal
phase/pregnancy
d. Breast feeding; prevents ovulation; GnRH pulse
disrupted – not enough LH to ovulate
Early pill: only estrogen release
Simulate uterine (baarmoeder) proliferation
Inhibitory effect on proliferation of the other follicles
Menstrual cycle
Female fertility is cyclic (28 days)– ovulation once a month – first cycle is menarche –
fertile period is 14 days before onset next cycle – conception risk highest 2-3 days
before ovulation
Maturation & release of egg
Preparation of uterus for fertilised egg
Male fertility is constant – survive 3-4 days in uterine tubes
Optimal fertility is between 20-30 years. Girls nowadays becomes sexually mature
women earlier becausee they are growing faster so reaching reproductive maturity at
earlier ages but their brains are not fully mature!
Menopause
Cessation (ophouden) of spontaneous menstruation:
Around 48-51 years because of exhausting (uitputting) of follicles in ovary.
FSH and LH are elevated (verhoogd)
Surgical menopause – oophorectomy is removal of ovaries
Temporary pharmacological menopause (pill) – GnRH in non-pulsatile form
Determination of normal menopause;
Genetics
Employment status
Divorcement status
Smoking – decrease length of normal cycle & shorter peri-menopause
duration (period before the menopause the menstruation is changing)
Menopause is associated with osteoporosis, diabetes, cardiovascular disease –
taking birth control pill may help in cases of perimenopausal symptoms
Birth control
Allows coupled to plan family size, allow women to become sexually independent,
can be used to prevent transmission of sexually transmitted diseases (STDs)
Two methods:
1. Rhythm method; avoid sex on peak of fertility
2. Contraception method – prevent ovulation
a. Barrier contraceptive (condom); limits the transmission of STDs
b. Intrauterine devices (IUDs) (spiraaltjes); do not prevent implantation but
sperm migration, ovum transport and fertilization
c. Pill use; mimics (nabootsen) conditions in luteal
phase/pregnancy
d. Breast feeding; prevents ovulation; GnRH pulse
disrupted – not enough LH to ovulate
Early pill: only estrogen release
Simulate uterine (baarmoeder) proliferation
Inhibitory effect on proliferation of the other follicles
