Animal Reproduction and Development. Overview Asexual Reproduction Binary fission budding...
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Transcript of Animal Reproduction and Development. Overview Asexual Reproduction Binary fission budding...
Animal Reproduction and Development
Overview• Asexual Reproduction • Binary fission • budding • fragmentation & regeneration • Sexual Reproduction • Gametogenesis-
production of egg and sperm
Reproductive cycles
• Hermaphroditism both male & female reproductive systems; sessile & burrowing organisms (earthworms)
Parthenogenesis
Egg development without fertilization• Aphid• Daphnia• Honeybee• Whiptail
lizard
Parthenogenic lizard
· Sequential hermaphroditism: an individual reverses its sex during its lifetime.
· Protogynous: female to male• Protandrous: male to female
Mechanisms of sexual reproduction• Fertilization
• external-outside the body
• internal- inside the body
• Pheromones- chemical signals that influence the behavior of others (mate attractants)
Regulating Hormones
• Testosterone in males
• Progesterone and estrogen in females
Spermatogenesis
HypothalamusHypothalamus
Anterior PituitaryAnterior Pituitary
Gonadotropin Releasing hormone
Follicle stimulating hormone
Luteinizing Hormone
Hormonal Control of
Spermatogenesis
Oogenesis in the Ovary
OvaryOvary
Luteinizing Hormone
Estrogen
Follicle StimulatingHormone
Female Hormonal Cycle
The female patternEstrous cycles (many
mammals)Menstrual cycle
(humans and many other primates
Ovarian/Menstrual cycles~
1. follicular phase ~follicle growth
2. Ovulation ~ oocyte release
3. luteal phase ~ hormone release
Amniote embryos• •yolk sac (support;
circulatory function) •amnion (fluid-filled sac; protection) •chorion (placenta formation)
• •allantois (nitrogenous waste)
Embryonic Development
Ultrasound Imagery
Teratogens• Substances that
may harm the developing fetus and result in the formation of birth defects
• Alcohol, certain drugs/medications, infections, and certain chemicals
Organogenesis: organ formation
• Primitive streak~ invagination of blastodisc
• Neural tube~ beginning of spinal cord
• Somites~ vertebrae and skeletal muscles
• Neural crest~ bones and muscles of skull
Morphogenesis and Cell Movement• CAMS- cell adhesion molecules- build
tissue• Induction-gene expression and chemical
signals bring about differentiation• Restriction of cellular potency- only
zygote is totipotent (capable of developing into all cell types)
• Organizer regions -signal molecules secreted by this region influence gene expression
Stem Cells
Limb Formation
Limb “buds” form from
Apical ectodermal ridge-in the ectoderm at the tip
Zone of polarizing activity-mesoderm tissue