This document summarizes key aspects of animal reproduction and development. It discusses asexual and sexual reproduction, including the components of reproductive systems and processes like fertilization, cleavage, and gastrulation. It also describes embryonic development, including the formation of extraembryonic membranes in different animal groups and the roles of structures like the blastocyst, chorion, amnion, yolk sac, and allantois in mammalian development.

1. Animal Reproduction and DevelopmentBy: Xander Posner

2. Methods of asexual reproduction.Pheromones in mating attraction.Different sexual reproductive methods.Components of reproductive system.Methods of fertilization.Process of CleavageCell stages, gastrulation, etc.Extraembryonic membranesOverview

3. Asexual (meaning without sex) reproduction - Creation of new individuals from which all of the gametes come from one parent, without meeting of gametes. Does NOT increase genetic diversity.Sexual Reproduction – Creation of offspring by the fusion of haploid gametes to form a zygote (fertilized egg) which is diploid. Increases genetic diversitySperm – Small, motile, male sex cell.Ovum (Egg) – Larger, not motile, female sex cellKey Terms

4. There are four types.FissionBuddingFragmentation & RegenerationParthenogenesisTypes of Asexual ReproductionFission in Amoeba 

5. Parthenogenesis is a process in which an egg develops without fertilization.Occurs in crustaceans, bees, wasps, ants, reptiles and others.The switching from asexual to sexual reproduction is usually induced by season or other environmental stress.Plays large role in ant and bee colonies where fertile females become queens and the sterile individuals in which meiosis never occurred become worker ants or bees. http://www.hippocampus.org/homework-help/Biology/The%20Reproduction%20of%20Cells_Sexual%20Life%20Cycle%20&%20Meiosis-%20Summary.htmlParthenogenesis

6. Chemical signals released by animals that play large role in mate attractionReleased into air, can be sensed by animals such as bees over a Km away.Occur in minute amounts, like hormones.Pheromones

7. Reproductive SystemsOviductOvaries(Urinarybladder)Seminal vesicleFolliclesEndometrium(Rectum)(Pubic bone)Uterine wallUterusCervixErectiletissue ofpenisCorpus luteumVas deferensEjaculatory ductProstate glandUrethraBulbourethral glandGlans penisVas deferensEpididymisVaginaTestisPrepuceScrotum

8. Menstrual cycle occurs due to changes in the uterus. Also called uterine cycle.Caused by cyclic events in the ovaries, or by the ovarian cycle.Female CyclesFigure 46.13

9. Sexual reproduction involves meiosis (to create gametes) But how do these gametes come about you may ask?Oogenesis – Creation of female ova. Figure 46.11Spermatogenesis – Creation of male sperm cells. Figure 46.12Creation of Gametes

10. Begins with fertilization – meeting of gametes.Once egg is fertilized, activation of the egg occurs and rapid changes result. Some changes are:Increase in cytoplasmic Calcium (Ca2+), which hardens the egg lining, preventing additional sperm from entering.This increase in Ca2+ also increases rates of cellular respiration and protein synthesis by the egg cell.The sperm nucleus within the egg cell begins to swell. After about 20 minutes, the nucleus of the sperm and egg fuse, forming the diploid zygote and BAM, the beginning of new life.Development

11. FertilizationSea UrchinsGametes meet externally when they are released into surrounding water.Acrosomal reaction, when urchin sperm release hydrolytic enzymes to break down the jelly coat of an egg cell and enter it.Once a sperm penetrates, the gametes plasma membranes fuse, rapidly preventing polyspermy.Cortial Reaction – Sperm binding induces signal transduction pathway that induces a long-term prevention of polyspermy.MammalsGametes meet internally after sperm swim up the fallopian tubes.Sperm binds to membrane of egg.Virtually same acrosomal reaction occurs. Once sperm breaks down the outer coating of the egg cell, membrane proteins of the sperm bind to receptors in the egg and the plasma membranes fuse.Sperm nucleus and other components enter egg cell.Enzymes are released during the cortical reaction that block polyspermy.

12. After fertilization, rapid cell divisions occur.This process is called cleavage.Cells undergo the S (DNA synthesis) and M (Mitosis) stages but skip the G phases so virtually no protein synthesis occurs. Each new cell has its own nucleus. Cell divides into about 128 cells until the blastula is created.Blastula is a hollow ball of cells.Cleavage… The Cell Type

13. Gastrulation is the infolding of the blastula forming 3 cell “germ” layers and the cell’s primitive gut. Process of infolding is called invaginationAllows new interactions of cells3 Layers created are:Ectoderm (Outer layer)Endoderm (lines the embryonic digestive tract)Mesoderm (Which partly fills space between the ectoderm and endoderm)GastrulationVIDEO TIME

14. Membranes associated with animals that aid in their embryonic development.Adaptations that allow live or shelled egg birth on land.Found in reptiles (and birds), and mammals.4 extraembryonic membranes of birds and reptiles are:The amnion (Prevents dehydration and cushions)The allantois (Disposal sac for metabolic waste, and as respiratory organ)The Chorion (exchange gases between embryo and surrounding air)The Yolk sac (Stockpile of nutrients for embryo)All arise from 3 germ layers.Extraembryonic Membranes

15. Blastocyst is hollow ball of cells; mammalian version of blastula.Cluster of cells within blastocyst called inner mass cells will contribute most of the extraembryonic membranes.Trophoblast is part of the blastocyst that secretes hydrolytic enzymes that allow the blastocyst to enter the lining of the uterus.Gastrulation occurs once the blastocyst is implanted in the uterine lining. The 3 germ layers formed by the end of gastrulation form the extraembryonic membranes. The membranes created are:The chorion (gas exchange)The amnion (encloses embryo in protective fluid, this fluid exits the vagina when a woman’s “water breaks,” before childbirth)The yolk sac (encloses fluid filled cavity, site of early formation of blood cells.)The allantois (incorporated into the umbilical cord, forms blood vessels that transport oxygen and nutrients from the placenta to the embryo and also function in removal of waste.By the end of the first trimester of pregnancy, rudiments of all the major organs have developed from the 3 germ layers.Mammalian DevelopmentTHE END