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The signals sent within the oocyte cell that a sperm has fertilized the oocyte, or in the case of cloning, the molecular mimicry of the sperm’s activity to initiate development.


Biological materials such as genes, proteins, cells, tissues, or organs used for transplantation and derived from another donor individual of the same species as the recipient.

Animal Cloning

The making of essentially genetically exact copies of animals.


Biological materials such as cells, tissues, or organs used for transplantation and derived from the recipient himself.

Autologous Regenerative Medicine

Transplantation of cells, tissues, or organs derived from and genetically essentially identical to the recipient himself.


An embryo at the stage of a microscopic ball of approximately 40-100 cells often referred to as a “pre-embryo” as individualization has not yet occurred.

Cell Cycle

The life cycle of a cell, usually divided into the phase when DNA is replicated (S phase), the phase when the cell actually divides into two cells (M phase), the two intervening gap phases (G1 and G2) and a nondividing state called “quiescence” (G0).

Cellular Aging

Most cells in the human body can replicate only a finite number of times and then cease dividing in what is called cell aging, or cell senescence.


An animal made of cells from what would normally be two separate animals each with unique DNA.


The visible form DNA takes within the cell. A chromosome is a compacted and packaged form of DNA. Usually an animal’s DNA is in multiple chromosomes. Human cells have 46 chromosomes.

Clone, cloning

The production of an animal with nuclear DNA identical to another animal. Cloning takes place without the contribution of DNA from a male and female, and is therefore “asexual” reproduction.


Cells are often thought of being composed of a small entity called the nucleus containing the DNA that resides within a larger “sack” of molecules called the cytoplasm within which many cellular processes occur.

Deoxyribonucleic acid (DNA)

The blueprint of life composed of four “letters” A, C, T, and G that in their unique ordering make a molecular code for the organization of life.


The process by which a primitive cell commits to becoming a specialized cell in the body, such as a skin cell, or a bone cell.


The removal of the nucleus from a cell. Because the egg cells often used in cloning are in a special stage called MII oocytes and don’t actually have a nucleus, but rather have free chromosomes, the term is used loosely for the removal of the nuclear DNA


A cell commonly grown in the laboratory because of the ease with which they can be cultured and made to proliferate.

G0 Phase

A phase of the cell cycle, see “cell cycle”.

G1 Phase

A phase of the cell cycle, see “cell cycle”.

G2 Phase

A phase of the cell cycle, see “cell cycle”.


A small region of the strand of DNA that often provides the instructions for a single protein molecule.

Genetic Programming

The precise engineering of the genome of animals.


The science of identifying the sequence of DNA in various species, and subsequent processing of that information.


The lineage of cells that connect the generations. The sperm and the egg are examples of germline cells.


While human cells generally have a finite capacity to divide, they can occasionally be made to divide without limit, usually by restoring telomeres through the protein telomerase. Cells that divide without limit are said to be immortal. The process of transforming a mortal cell to immortality is immortalization.

M Phase

A phase of the cell cycle, see “cell cycle”.


The formation of germ cells where the chromosome number is reduced in half.


The process of cell division where the DNA is replicated and one cell becomes two complete cells.

Nuclear Transfer

A general term for the process of cloning where the genetic information from a body cell is transferred to an egg cell whose DNA is removed.


The small region in a cell that contains the DNA.


The diploid egg cell before meiosis is complete.


Literally “virgin birth”, parthenogenesis refers to the activation of an egg cell and subsequent development without the use of a sperm cell.


A stem cell that can become numerous cell types.


A stem cell that can become numerous cell types.

Primordial Germ Cells (PSCs)

Totipotent stem cells, such as embryonic stem cells, embryonic germcells and other cells capable of forming any cell type in the body.

Primordial Stem Cells (PSC)

A totipotent cell that comes from a preimplantation embryo. Because it is undifferentiated, it has the potential of transforming into all cell types.


The region of DNA near a gene that prompts the gene to be “on” or “off”.


The G0, or resting phase of the cell cycle.

Recombinant DNA Technology

The techniques that allows the cutting and splicing of DNA in a precise manner allowing the engineering of DNA sequence.

Regenerative Medicine

The creation and transplantation of healthy cells, tissues, and organs to replace or repair a medical patient’s own damaged or diseased cells, tissues, and organs.

S Phase

A phase of the cell cycle, see “cell cycle”.


See Somatic Cell Nuclear Transfer.

Somatic Cell

A body cell, as opposed to a germ line cell.

Somatic Cell Nuclear Transfer (SCNT)

The process of combining a somatic cell, with an oocyte from which the nucleus has been removed. Also called Cloning.

Stem Cell

A cell capable of branching out and becoming different kinds of cells.


The stimulation of the ovary to release more than the normal number of egg cells.


The protein that produces the telomeric DNA. Cells that have sufficient telomerase often do not age, that is, they are immortal.


The linear ends of the DNA molecule of most species. In the case of mammals, the ends are composed of the sequence “TTAGGG” repeated thousands of times. Telomeres are a “clock” of cellular aging, shortening over time in many cell types.


A stem cell that can become all cell types.


The stable introduction of modified genes or genes from another animal or species into an animal’s genome.

Transgenic Animal Cloning

The cloning or copying of a genetically modified animal such as a cow modified to produce pharmaceutical proteins in its milk, or a mouse modified to model a human disease.


The transfer of cells or tissues from one species to another.