EGL USA is one of the largest and oldest independent gemological institutions focusing on gemstone certification and research. Originally part of an international network founded in Europe in 1974, EGL USA opened its first U.S. lab in the heart of New York's international diamond and jewelry district in 1977.
the fusion of the nucleus of a haploid sperm cell and the nucleus of a haploid egg cell, forming a diploid zygote zygote diploid cell formed when the nucleus of a haploid sperm cell fuses with the nucleus of a haploid egg cell tetrad group of four chromatids formed during prophase I of meiosis by the two sister chromatids in each of the two homologous chromosomes
106 â A CHAPTER 4 Cell Reproduction Sexual Reproduction Another way that a new organism can be produced is by sex-ual reproduction. During sexual reproduction, two sex cells,sometimes called an egg and a sperm, come together. Sex cells,like those in Figure 9, are formed from cells in reproductiveorgans.Sperm are formed in the male reproductive organs. Eggs are formed in the female reproductive organs.The joiningof an egg and a sperm is called fertilization, and the cell thatforms is called a zygote (ZI goht).Generally, the egg and thesperm come from two different organisms of the same species.Following fertilization, mitosis and cell division begins.he joiningof an egg and a sperm is called fertilization, and the cell thatforms is called a zygote (ZI goht). Generally, the egg and thesperm come from two different organisms of the same species.Following fertilization, mitosis and cell division begins.