Reproductive Cycles Annual Breeding Cycles Continuous breeders Breeds throughout the year e.g., human,. guinea pig, rat. Seasonal breeders Breeds during specific seasons e.g., dog , cat, sheep. cattle Oestrus cycle Females sexually receptive during heat period e.g., cow, rat, pig Menstrual cycle Periodical discharge of menstruation e.g., monkeys. Ape, man
First, the donor cells are grown under special conditions in culture. The number of cells can be increased by several orders of magnitude. It is also possible to make genetic modifications and to select just those cells in which the desired modification has occurred and multiply these up.
These cells are then fused with an unfertilised egg from which the introduced nucleus can lead to the formation of an embryo.
The embryos are then transplanted into sheep and lambs are born naturally.
This technology could allow the production of genetically identical groups of animals which possess a desirable genetic trait.
Cure for heart problems:. possible to treat heart attack victims by cloning their healthy heart cells and injecting them into the areas of the heart that have been damaged.
Organ and tissue repair: Embryonic stem cells can be grown to produce organs or tissues to repair or replace damaged ones. Skin for burn victims, brain cells for the brain damaged, spinal cord cells for quadriplegics and paraplegics, hearts, lungs, livers, and kidneys could be produced.
Cure for Incurable diseases: Conditions such as Alzheimer's disease, Parkinson's disease, diabetes, heart failure, degenerative joint disease, and other problems may be made curable.
5. Infertility: Human cloning could make it possible for infertile couples to have children .
6. Plastic, reconstructive, and cosmetic surgery: Instead of using materials foreign to the body for such procedures, doctors will be able to manufacture bone, fat, connective tissue, or cartilage that matches the patients tissues exactly.