asexual reproduction in a sea anemone. overview: doubling up for sexual reproduction the two...
TRANSCRIPT
• Overview: Doubling Up for Sexual Reproduction
• The two earthworms in this picture are mating
• Each worm produces both sperm and eggs, which will fertilize– And in a few weeks, new worms will hatch
Figure 46.1
Sexual Behavior in Parthenogenetic Lizards (all female); adults are haploid
(a)
The female on the back inducesdevelopment of an egg duringcritical times of the hormone cycle
Sex Reversal in a Sequential Hermaphrodite
Females (yellow)
Male (Blue)
All are bornfemale and the largest complete livesas males
• Many different types of animals
– Exhibit parental care to ensure survival of offspring
Figure 46.6
Follicle Phase (lasts 10-14 days)
• starts when hypothalamus re-
leases GnRH that stimulates the
pituitary gland
FSH stimulates cell division in the
follicle, a layer of cells that sur-rounds the immature egg.
Thesecells supply nutrients to the
egg and secrete estrogen.
Ovulation (last 3-4 days)
•when a woman is most likely to getpregnant
•occurs when LH and FSH levels peak
•follicle releases the egg into the fallopian tube
Luteal Phase (lasts about 14 days)
•After ovulation the structure isnow called the corpus luteum.It secretes large amount of estro-gen and progesterone to maintainthe lining of the uterus until the egg is fertilized.
Menstruation (approx 5 days)
•occurs when the endometriumstarts to slough off; the lining ofthe uterus and ruptured bloodvessels are discharged through the vagina
• Mechanisms of Some Contraceptive Methods
Figure 46.20
Male Female
Method Event Event Method
Production ofviable sperm
Production ofviable oocytes
VasectomyCombinationbirth control pill (or injection,patch, orvaginal ring)Sperm transport
down maleduct system
Ovulation
Abstinence
Condom
Coitusinterruptus(very highfailure rate)
Spermdepositedin vagina
Capture of theoocyte by the
oviduct
Abstinence
Tubal ligation
Spermicides;diaphragm;cervical cap;progestin alone(minipill, implant,or injection)
Sperm movementthrough female
reproductivetract
Transportof oocyte in
oviduct
Meeting of sperm and oocytein oviduct
Morning-after pill (MAP)Union of sperm and egg
Implantation of blastocyst in properly prepared
endometrium
Birth
Progestin alone
Sperm are made in the ______________ and mature in the _______.
The function of the prostate gland is to . . .
Fertilization occurs in the . . .
Ovulation occurs when the levels of_____ and _____ peak.
Give an example of negative feed-back using the hormones of the menstrual cycle.
A woman is most likely to get pregnant at which time of the month?