Chapter 46

Animal Reproduction

AP BiologyPerri Pfrommer

Types of Reproduction

• Asexual Reproduction – One parent– No sperm & egg fusion

• Sexual Reproduction – Fusion of sperm & egg

Sea Anemone

Human Couple

Asexual Reproduction

• Types :– Fission (most common)– Budding– Fragmentation (followed by Regeneration)

• Advantages :– Isolated animals can reproduce – Many offspring created

Regenerating starfish

Other Reproductive Options• Switch between Asexual and Sexual

• Hermaphroditism – Male and Female systems

• Sequential Hermaphroditism– Change during lifetime

Blue-head Fish

earthworm

Bees

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

– Embryo can develop within reproductive tract

Snake Egg Shells

Kangaroo Baby-Pouch

Types of Gametogenesis- gamete production

• Spermatogenesis (Males)– Sperm cells– Seminiferous Tubes– Constant production

• Oogenesis (Females)– Egg cells– “resisting” periods

Female Hormones

• Hormones control Reproductive cycletypes 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

• (Organogenesis) Organs begin developing

• 8 weeks – Embryo is a Fetus

• Changes for Mother as well

Ultrasound Photo

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 BabyWhy??

• 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