Glossary 
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Cornea: Transparent tissue at the front of the eye. 
Cryopreserved embryos: Embryos, generally those produced by in 
vitro fertilization exceeding the number that can be transferred for 
uterine implantation, that have been frozen. 
Culture medium; The broth that covers cells in a culture dish, which 
contains nutrients to feed the cells as well as other growth factors 
that may be added to direct desired changes in the cells. (NIH) 
Dental pulp: The soft part inside a tooth, containing blood vessels 
and nerves. 
Diploid: Refers to the full complement of chromosomes in a somatic 
cell, distinct for each species (forty-six in human beings). (CR) 
Diploid human cell: A cell having forty-six chromosomes. (CR) 
Ectoderm: Upper, outermost layer of a group of cells derived from the 
inner cell mass of the blastocyst; it gives rise to skin nerves and 
brain. (NIH) 
Edmonton protocol: A procedure (developed in Canada) for trans- 
planting pancreatic islet cells to the hver of a patient with Type I 
diabetes. 
Embryo: (a) In humans, the developing organism from the time of 
fertilization until the end of the eighth week of gestation, when it 
becomes known as a fetus. (NIH) (b) The developing organism from 
the time of fertilization until significant differentiation has occurred, 
when the organism becomes known as a fetus. An organism in the 
early stages of development. (CR) 
Embryonic germ cells: Cells found in a specific part of the em- 
bryo/fetus called the gonadal ridge that normally develop into ma- 
ture gametes. (NIH) 
Embryonic stem cells: Primitive (undifferentiated) cells from the em- 
bryo that have the potential to become wide variety of specialized 
cell types. (NIH) 
Embryonic stem cell line: Embryonic stem cells, which have been 
cultured under in vitro conditions that allow proliferation without 
differentiation for months to years. (NIH) 
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