Scientists created human egg cells from skin cells

average: (in science) A term for the arithmetic mean, which is the sum of a group of numbers that is then divided by the size of the group.

cancer: Any of more than 100 different diseases, each characterized by the rapid, uncontrolled growth of abnormal cells. The development and growth of cancers, also known as malignancies, can lead to tumors, pain and death.

cell: (in biology) The smallest structural and functional unit of an organism. Typically too small to see with the unaided eye, it consists of a watery fluid surrounded by a membrane or wall. Depending on their size, animals are made of anywhere from thousands to trillions of cells. Most organisms, such as yeasts, molds, bacteria and some algae, are composed of only one cell.

chemical: A substance formed from two or more atoms that unite (bond) in a fixed proportion and structure. For example, water is a chemical made when two hydrogen atoms bond to one oxygen atom. Its chemical formula is H₂O. Chemical also can be an adjective to describe properties of materials that are the result of various reactions between different compounds.

chromosome: A single threadlike piece of coiled DNA found in a cell’s nucleus. A chromosome is generally X-shaped in animals and plants. Some segments of DNA in a chromosome are genes. Other segments of DNA in a chromosome are landing pads for proteins. The function of other segments of DNA in chromosomes is still not fully understood by scientists.

clinical trial: A research trial that involves people.

DNA: (short for deoxyribonucleic acid) A long, double-stranded and spiral-shaped molecule inside most living cells that carries genetic instructions. It is built on a backbone of phosphorus, oxygen, and carbon atoms. In all living things, from plants and animals to microbes, these instructions tell cells which molecules to make.

egg: A reproductive cell that contains half of the genetic information necessary to form a complete organism. In humans and in many other animals, ovaries produce eggs. When an egg fuses with a sperm, they combine to produce a new cell, called a zygote. This is the first step in the development of a new organism.”

embryo: The early stages of a developing organism, or animal with a backbone, consisting of only one or a few cells. As an adjective, the term would be embryonic — and could be used to refer to the early stages or life of a system or technology.

fusion: (v. to fuse) The merging of two things to form a new combined entity.

molecule: A group of atoms that represents the smallest possible amount of a chemical compound. Molecules can be made of single types of atoms or of different types. For example, the oxygen in air is made of two bound oxygen atoms (O₂). Water is made of two hydrogen atoms and one oxygen atom (H₂O).

nucleus: Plural is nuclei. (in biology) A dense structure present in many cells. Typically a single rounded structure encased within a membrane, the nucleus contains the genetic information.

pup: A term given to the young of many animals, from dogs and mice to seals.

sperm: A reproductive cell that contains half of the genetic information necessary to form a complete organism. In humans and in many other animals, testes produce sperm. When a sperm fuses with an egg, the two combine to produce a new cell, called a zygote. This is the first step in the development of a new organism.”

technology: The application of scientific knowledge for practical purposes, or the devices, processes and systems that result from those efforts.

Y chromosome: A portion of an animal’s genetic inheritance that appears on a sex chromosome known as “Y”. Males will usually have a Y- and an X-chromosome. Females ordinarily have no Y-chromosomes.

zygote: A cell that forms when two gametes fuse. in humans, those gametes are an egg and sperm. In plants, the gametes are pollen grains and ova.