module17-19

• After an egg is fertilized, and has fused with sperm to form a zygote, an embryo begins to develop. The process in which an organism develops from a single-celled zygote to a multi-cellular organism is complex and well-regulated.
• The typical blastula is a ball of cells.
• The cells in the blastula rearrange themselves spatially to form three layers of cells. This process is called gastrulation.
• During gastrulation, the blastula folds upon itself to form the three layers of cells. Each of these layers is called a germ layer and each germ layer differentiates into different organ systems.
• The three germs layers, are the endoderm, the ectoderm, and the mesoderm
• The ectoderm gives rise to the nervous system and the epidermis
• The mesoderm gives rise to the muscle cells and connective tissue in the body.
• The endoderm gives rise to columnar cells found in the digestive system and many internal organs
• Eugenics is the use of information and technology from a variety of sources to improve the genetic makeup of the human race.
• In fact, eugenicist Robert Klark Graham established a sperm bank in 1980 that included samples exclusively from donors with high IQs.
• In more recent times, the procedure known as prenatal genetic diagnosis (PGD) has been developed. PGD involves the screening of human embryos as part of the process of in vitro fertilization, during which embryos are conceived and grown outside the mother’s body for some period of time before they are implanted. The term PGD usually refers to both the diagnosis, selection, and the implantation of the selected embryos.
• To others, to purposely cause a disability in a child violates the basic medical principle of Primum non nocere, “first, do no harm.” This procedure, although not illegal in most countries, demonstrates the complexity of ethical issues associated with choosing genetic traits in offspring.