Parthenogenesis ( /ˌpærθənoʊˈdʒɛnəsɪs/) is a form of asexual reproduction where growth and development of embryos occur without fertilization. In plants, parthenogenesis means development of an embryo from an unfertilized egg cell, and is a component process of apomixis.

Gynogenesis and pseudogamy are closely related phenomena where a sperm or pollen triggers the development of the egg cell into an embryo but makes no genetic contribution to the embryo. The rest of the cytology and genetics of these phenomena are mostly identical to that of parthenogenesis.

The word parthenogenesis comes from the Greek παρθένος, parthenos, meaning "virgin", and γένεσις, genesis, meaning "birth". The term is sometimes used inaccurately to describe reproduction modes in hermaphroditic species that can reproduce by themselves because they contain reproductive organs of both sexes in a single individual's body.

Parthenogenesis occurs naturally in many plants, some invertebrate animal species (including nematodes, water fleas, some scorpions, aphids, some bees, some Phasmida, and parasitic wasps) and a few vertebrates (such as some fish,amphibians, reptiles, and very rarely birds). This type of reproduction has been induced artificially in a few species including fish and amphibians.

Henrietta Lacks (August 1, 1920 – October 4, 1951) (sometimes erroneously called Henrietta Lakes, Helen Lane or Helen Larson) was an African-American woman who was the unwitting source of cells (from her cancerous tumor), which were cultured by George Otto Gey to create an immortal cell line for medical research. This is now known as the HeLa cell line.

Henrietta Lacks was born Loretta Pleasant on August 1, 1920 in Roanoke, Virginia, to Eliza (1886–1924) and John Randall Pleasant I (1881–1969). Her family is uncertain how her name changed from Loretta to Henrietta. Eliza, her mother, died giving birth to her tenth child in 1924. Henrietta's father felt unable to handle the children, so he took them all to Clover, Virginia and distributed the children between relatives. Henrietta, nicknamed Hennie, ended up with her grandfather, Tommy Lacks.

Pleasant married her first cousin, David "Day" Lacks (1915–2002), in Halifax County, Virginia. David had already been living with Henrietta's grandfather when she moved there at age 4. Their marriage on April 10, 1941, after their first two children were born (the first when Henrietta was just 14), surprised many in the family as they had been raised like brother and sister.