Animal Reproduction Biology 155 Krilowicz Spring 2010

I. Asexual versus Sexual Reproduction A. Asexual Reproduction – reproduction that produces individuals who are genetically identical to the parents –Examples – budding in sea anemones, fragmentation in sea stars budding in a hydra

I.Asexual versus Sexual Reproduction- continued B. Sexual Reproduction – reproduction that produces offspring who are genetically different from either parent, requires production of gametes (eggs and sperm) that fuse to form a fertile egg - Example - humans

II. Internal versus External Fertilization A.External Fertilization – used by aquatic animals 1.Eggs and sperm are discharged into the water where fertilization occurs 2.Requires lots of gametes to ensure – a.Fertilization occurs b.A few of the fertile eggs survive and complete development 3. Embryological development occurs in water, outside body

B. Internal Fertilization - Used by some aquatic animals and all terrestrial animals 1.Sperm are deposited directly into the female’s body to protect the gametes 2.Requires development of – a. Male copulatory organ (penis) b. Female organ to receive penis (vagina)

B. Internal Fertilization - continued 3. Embryological development post- fertilization can be – a. oviparous – eggs laid and hatch outside the body (examples – birds, reptiles)

B. Internal Fertilization - continued 3. Embryological development post- fertilization can be – b. ovoviviparous – eggs develop inside of female’s body, but do not receive nourishment from her (example – some sharks)

B. Internal Fertilization - continued 3. Embryological development – continued c. Viviparous – embryos develop in female’s body and receive nourishment directly from her, often using a placenta (example – mammals)

B. Internal Fertilization - continued 4. Young that hatch or are born can be – a. precocial – highly developed and able to move about and feed themselves, “miniature adults” (example – reptiles)

B. Internal Fertilization - continued 4. Young that hatch or are born can be – b. altricial - immature and require considerable parental care to survive c. Note the energetic trade off between parental investment in lots of gametes versus significant parental care of young

III. Human Reproduction A.There are two basic types of reproductive system organs – 1.Gonads = primary sex organs = essential sex organs; ovary and testis a.Produce the gametes b.Produce the sex hormones that – 1.Regulate the reproductive process 2.Regulate development and function of the other reproductive system organs

A. Types of reproduction system organs - continued 2. Secondary sex organs = accessory sex organs; involved in - a. transport b. protection c. nourishment of the gametes, embryo or young

B. The human male reproductive system Add 60% of fluid to semen; contains fructose (energy source), prostaglandins, proteins to coagulate semen in vagina Adds seminal fluids to neutralize acidic urethra and vagina Purpose? Houses testes outside abdominal cavity since sperm production does not occur at normal body temperature Copulatory organ Inguinal canal Common exit for urinary and reproductive system Fig 27.4

The human male primary sex organ and associated organs Testes = primary sex organ; spermatogenesis occurs in seminiferous tubules, testosterone production occurs in cells of Leydig Site of final sperm maturation, takes several weeks Sperm transport – through inguinal canal to abdominal cavity out urethra, fluids added along the way Fig. 27.5A

C. The Human Female Reproductive System Muscular organ for implantation and development of the fetus Extension of uterus into the vagina Muscular canal for reception of penis and passage of infant at birth Note separate exits for urinary and reproduction systems Fig. 27.3

The human female primary sex organ and associated organs Ovary = primary sex organ; egg production and estrogen and progesterone production all occur within the follicles Oviduct = fallopian tube, site of fertilization of the egg, transport of egg from ovary to uterus uterus Fig. 27.3