1. Comparative Vertebrate Physiology
Fertilization and nurturing of the embryo and young

2. Fertilization Sequence of events Sperm capacitation
Acrosomal enzymes weaken oocyte membrane
Sperm nucleus and centriole penetrates into the ovum
Monospermy is assured by:
Entry of extracellular Na+ reversing oocyte membrane polarity
Ca++ causes cell to prepare for cell division
This cortical reaction destroys sperm receptors on plasma membrane

3. Reproductive synchrony
Development/release of gametes from male and female done simultaneously
e.g. development of bird testes
Environmental cues (temp., day length)

4. Hormones Viability of the corpus luteum maintained by hCG
Levels of estrogen and progesterone rise due to secretion by the placenta
Estrogen and progesterone levels rise in anticipation of birthing and lactation

5. Birthing
Involuntary contractions of uterine smooth muscle (positive feedback)

6. Birthing
Amniotic sac pushes up against cervix wall (“breaking of water”)
Birth follows
Further uterine contraction expels the placenta

7. Lactation
Rising estrogen and progesterone levels stimulate release of PRH
Lactogenesis
Colostrum is the first milk
Humans: little fat, mostly protein, vitamins, antibodies
Marine mammals: 58% fat in seals

8. Milk let down reflex
Positive feedback (galactopoiesis)