Chapter 46
Animal Reproduction
AP Biology
Perri Pfrommer
Types of Reproduction
• Asexual Reproduction
– One parent
– No sperm & egg fusion
Sea Anemone
• Sexual Reproduction
– Fusion of sperm & egg
Human Couple
Asexual Reproduction
• Types :
– Fission (most common)
– Budding
Regenerating starfish
– Fragmentation (followed by Regeneration)
• Advantages :
– Isolated animals can reproduce
– Many offspring created
Other Reproductive Options
• Switch between Asexual and Sexual
• Hermaphroditism
– Male and Female systems
Bees
earthworm
• Sequential Hermaphroditism
– Change during lifetime
Blue-head Fish
Fertilization
• Two Types:
– External Fertilization
• Moist habitat
• Lot of zygotes – small # develop
– Internal Fertilization
• Adaptation for Terrestrial Animals ->
– Dry habitat
• Less zygotes – more develop
• Pheromones
– Find a mate
Elephant
Ways to Protect Offspring
• Internal Fertilization’s zygotes have greater
protection
– Tough Eggshells
Snake Egg Shells
– Embryo can develop within
reproductive tract
Kangaroo BabyPouch
Types of Gametogenesis
- gamete production
• Spermatogenesis (Males)
– Sperm cells
– Seminiferous Tubes
– Constant production
• Oogenesis (Females)
– Egg cells
– “resisting” periods
Female Hormones
• Hormones control Reproductive cycle
types of hormones
– Gonadotropin – releasing hormone (GnRH)
– Gonadotropin follicle – stimulating hormone (FSH)
– Luteinizing hormone (LH)
• Main Female hormones
– Estrogen
– Progesterone
Male Hormones
• Principle Hormone – Androgens
– Testosterone most important
• Important part of male development
– Deeper voice
– Muscle growth
Embryo Development
• In 24 hours zygote divides
• 1 Week reaches embryonic stage – Blastocyst
• Embryo gives off hormones
– Human Chorionic Gonadotropin (HCG)
• Human pregnancy – Three Trimesters,
266 Days
First Trimester
• 2-4 weeks
– embryo obtains nutrients
– Trophoblast and Placenta form
Ultrasound Photo
• (Organogenesis) Organs begin developing
• 8 weeks – Embryo is a Fetus
• Changes for Mother as well
Second Trimester
• Growth/Activity
• Hormone stabilize
• Placenta develops
• Pregnancy becomes Obvious
Third Trimester
• Activity decrease
• Mother’s abdominal organs displaced
• Regulators+Hormones induce labor
Mother’s Immune System does not
reject Baby
Why??
• Hypothesizes –
– Trophoblast vs. T lymphocytes (T Cells)
• Releasing molecules with immunosuppressive effects
– Placenta vs. T Lymphocytes
• Gives of enzymes
Modern Technology and Pregnancies
• Ultrasounds
• Blood Samples from Mother
• Solutions to infertility problems
– A.R.T
– Hormone Therapy