Animal Reproduction

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11

1

Slide 77

Expulsion: delivery of the infant

2

Slide 78

Delivery of the placenta

Uterus

Placenta

(detaching)

Umbilical

cord

3

Slide 79

The three stages of labor

3

2

1

Dilation of the cervix

Placenta

Umbilical cord

Uterus

Cervix

Expulsion: delivery of the infant

Uterus

Placenta (detaching)

Umbilical cord

Delivery of the placenta

Slide 80

Birth, or parturition, is brought about by a series of strong, rhythic uterine contractions.

First the baby is delivered, and then the placenta.

Lactation = the production of milk. This is unique to mammals.

Slide 81

Maternal Immune Tolerance of the Embryo and Fetus

A woman’s acceptance of her “foreign” offspring is not fully understood.

It may be due to suppression of the immune response in her uterus.

Slide 82

Contraception and Abortion

Contraception, the deliberate prevention of pregnancy, can be achieved in a number of ways.

Contraceptive methods fall into three categories:

Preventing release of eggs and sperm

Keeping sperm and egg apart

Preventing implantation of an embryo.

Slide 83

Mechanisms of several contraceptive methods

Male

Female

Method

Event

Event

Method

Production of sperm

Production of primary oocytes

Vasectomy

Combination birth control pill (or injection, patch, or vaginal ring)

Sperm transport down male duct system

Oocyte development and ovulation

Abstinence

Condom

Coitus interruptus (very high failure rate)

Abstinence

Sperm deposited in vagina

Capture of the oocyte by the oviduct

Tubal ligation

Female condom

Sperm movement through female reproductive tract

Transport of oocyte in oviduct

Spermicides; diaphragm; cervical cap; progestin alone (as minipill, implant, or injection)

Meeting of sperm and oocyte in oviduct

Union of sperm and egg

Morning-after pill; intrauterine device (IUD)

Implantation of blastocyst in endometrium

Slide 84

Detecting Disorders During Pregnancy

Amniocentesis and chorionic villus sampling are invasive techniques in which amniotic fluid or fetal cells are obtained for genetic analysis.