Asexual Reproduction

in a Sea Anemone

• 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

The Release of Eggs and External Fertilization

Reproductive Anatomy of a Parasitic Flatworm

Reproductive Anatomy of the Human Male

Reproductive Anatomy of the Human Male

Seminiferous tubules (left), sperm in semen (right)

Structure of a Human Sperm Cell

Contains an enzymethat helps penetrate the egg

Reproductive Anatomy of the Human Female

Reproductive Anatomy of the Human Female

Menstrual Cycle (mensis = month)- lasts approx. 28 days

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.

Hormones of the Hypothalamus and Pituitary Glands

Nerve cells that release hormonesinto the blood

Ovary Follicle

Ovum

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

Oogenesis

Ovulation

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

The Reproductive cycle of the Human Female

Hormonal Control of the Testes

• 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

Formation of the Zygote and Early Postfertilization Events

Placental Circulation

Human Fetal Development

Hormonal Induction of Labor

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?

Describe the path of a sperm cell from where it is made to where itfertilizes the egg in a female. Hint: There are 7 structures involved.