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A zygote (from Greek ????t?? zugotos "joined" or "yoked", from ?????? zugoun "to join" or "to yoke") is a cell
Cell (biology)

The cell is the structural and functional unit of all known Life organisms. It is the smallest unit of an organism that is classified as living, and is often called the building bricks of life....
 that is the result of fertilization. That is, two haploid
Ploidy

Ploidy is the number of complete sets of non-homologous chromosomes in a biological cell. In humans, the somatic cells that comprise the body are diploid , but sex cells are haploid....
 cells—usually an ovum
Ovum

An ovum is a haploid female reproductive cell or gamete. Both animals and embryophytes have ova. The term ovule is used for the young ovum of an animal, as well as the plant structure that carries the female gametophyte and egg cell and develops into a seed after fertilization....
 from a female
Female

Female is the sex of an organism, or a part of an organism, which produces mobile ovum . The ova are defined as the larger gametes in a heterogamous reproduction system, while the smaller, usually motile gamete, the spermatozoon, is produced by the male....
 and a sperm
Sperm

The term sperm is derived from the Greek word sperma and refers to the male reproductive Cell . In the types of sexual reproduction known as anisogamy and oogamy, there is a marked difference in the size of the gametes with the smaller one being termed the "male" or sperm cell....
 cell from a male
Malé

Mal? , population 104,403 , is the Capital , the largest city in terms of population, and the name of an island in the Maldives. It is located at the southern edge of North Male' Atoll Kaafu Atoll....
—merge into a single diploid
Ploidy

Ploidy is the number of complete sets of non-homologous chromosomes in a biological cell. In humans, the somatic cells that comprise the body are diploid , but sex cells are haploid....
 cell called the zygote (or zygocyte). A zygote is the first cell of a new unique organism that has DNA from the mother and father.

A zygote begins as a fertilized egg (ovum), and contains all of the genetic information (DNA
DNA

Deoxyribonucleic acid is a nucleic acid that contains the genetics instructions used in the development and functioning of all known living organisms and some viruses....
) necessary to become a baby; half of that information is from the mother’s egg and half from the father’s sperm that has fertilized the egg.






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A zygote (from Greek ????t?? zugotos "joined" or "yoked", from ?????? zugoun "to join" or "to yoke") is a cell
Cell (biology)

The cell is the structural and functional unit of all known Life organisms. It is the smallest unit of an organism that is classified as living, and is often called the building bricks of life....
 that is the result of fertilization. That is, two haploid
Ploidy

Ploidy is the number of complete sets of non-homologous chromosomes in a biological cell. In humans, the somatic cells that comprise the body are diploid , but sex cells are haploid....
 cells—usually an ovum
Ovum

An ovum is a haploid female reproductive cell or gamete. Both animals and embryophytes have ova. The term ovule is used for the young ovum of an animal, as well as the plant structure that carries the female gametophyte and egg cell and develops into a seed after fertilization....
 from a female
Female

Female is the sex of an organism, or a part of an organism, which produces mobile ovum . The ova are defined as the larger gametes in a heterogamous reproduction system, while the smaller, usually motile gamete, the spermatozoon, is produced by the male....
 and a sperm
Sperm

The term sperm is derived from the Greek word sperma and refers to the male reproductive Cell . In the types of sexual reproduction known as anisogamy and oogamy, there is a marked difference in the size of the gametes with the smaller one being termed the "male" or sperm cell....
 cell from a male
Malé

Mal? , population 104,403 , is the Capital , the largest city in terms of population, and the name of an island in the Maldives. It is located at the southern edge of North Male' Atoll Kaafu Atoll....
—merge into a single diploid
Ploidy

Ploidy is the number of complete sets of non-homologous chromosomes in a biological cell. In humans, the somatic cells that comprise the body are diploid , but sex cells are haploid....
 cell called the zygote (or zygocyte). A zygote is the first cell of a new unique organism that has DNA from the mother and father.

A zygote begins as a fertilized egg (ovum), and contains all of the genetic information (DNA
DNA

Deoxyribonucleic acid is a nucleic acid that contains the genetics instructions used in the development and functioning of all known living organisms and some viruses....
) necessary to become a baby; half of that information is from the mother’s egg and half from the father’s sperm that has fertilized the egg. The organism in the zygote stage of life travels down the fallopian tube
Fallopian tube

The Fallopian tubes, named after Gabriel Fallopius , also known as oviducts, uterine tubes, and salpinges are two very fine tubes lined with cilia epithelia, leading from the ovaries of female mammals into the uterus....
, while dividing to form a larger group of cells
Cell division

Cell division is a process by which a cell , called the parent cell, divides into two or more cells, called daughter cells. Cell division is usually a small segment of a larger cell cycle....
. This cell division is mitotic
Mitosis

Mitosis is the process in which a eukaryotic cell separates the chromosomes in its cell nucleus, into two identical sets in two daughter nuclei....
, and is known as "cleavage
Cleavage (embryo)

In embryology, cleavage is the division of cell s in the early embryo. The zygotes of many species undergo rapid cell cycles with no significant growth, producing a cluster of cells the same size as the original zygote....
". All mammals go through the life stage of being in the zygote stage of life. After this life stage the organism goes through the life stages of an embryo, and a fetus. A human zygote exists for about four days, and becomes a blastocyst
Blastocyst

The blastocyst is the structure formed in early embryogenesis, after the formation of the blastocoel, but before implantation.It possesses an inner cell mass, or inner cell mass which subsequently forms the embryo proper, and an outer layer of cells, or trophoblast which later forms the placenta....
 on the fifth day.

Twins

Twin
Twin

Twins are two offspring resulting from the same pregnancy, usually childbirth in close succession. They can be the same or different sex. Twins can either be monozygotic or dizygotic ....
s and multiple birth
Multiple birth

A multiple birth occurs when more than one fetus is carried to term in a single pregnancy. Different names for multiple births are used, depending on the number of offspring....
s can be monozygotic (identical) or dizygotic (fraternal), meaning they arise from one or several (strictly, two) fertilization events. Polyspermic
Polyspermy

In biology, polyspermy describes an Ovum that has been Fertilisation by more than one Spermatozoon. Ploidy organisms normally contain two copies of each chromosome, one from each parent....
 zygotes in mice have been manipulated so as to remove one of the two male pronuclei
Pronucleus

A pronucleus is the nucleus of a sperm or an egg cell during the process of fertilization, after the sperm enters the ovum, but before they fuse....
 and made to survive birth.

Siamese/Conjoined Twins


Siamese or Conjoined twins occur in roughly 1 in every 200 identical twin pregnancies and are always identical. Actual numbers for conjoined births vary from 1 in 20,000 to 1 in 100,000 pregnancies, and 40-60% are stillborn, with many others dying within the first few days after birth. About 70% of conjoined twins are female, the reason for which is unknown.

Separation has been attempted on almost all conjoined twins born since the 1950s with varying results, although the first successful separation was performed in Basle, Switzerland in 1689 on twin girls born joined by a ligament at the sternum (xiphopagus). The first conjoined twins to be successfully separated in "modern" times are generally believed to be Catherine and Caroline Mouton of Louisiana, born joined at the lower back (pygopagus)and separated in 1953 at 8 days of age. Both survived the operation, but Catherine committed suicide in 1985.

In other species

A biparental zygote is a Chlamydomonas
Chlamydomonas

Chlamydomonas is a genus of green alga. They are unicellular flagellates. Chlamydomonas is used as a model organism for molecular biology, especially studies of flagellum motility and chloroplast dynamics, biogenesis, and genetics....
 (a kind of algae
Algae

Algae are a large and diverse group of simple, typically autotrophic organisms, ranging from unicellular to multicellular forms. The largest and most complex marine forms are called seaweeds....
) zygote that contains chloroplast
Chloroplast

Chloroplasts are organelles found in plant cells and other eukaryote organisms that conduct photosynthesis. Chloroplasts capture light energy to conserve Thermodynamic free energy in the form of Adenosine triphosphate and reduce NADP to NADPH through a complex set of processes called photosynthesis....
 DNA
DNA

Deoxyribonucleic acid is a nucleic acid that contains the genetics instructions used in the development and functioning of all known living organisms and some viruses....
 (cpDNA) from both parents.

See also

  • Sexual reproduction
    Sexual reproduction

    Sexual reproduction is characterized by processes that pass a Genetic recombination of Genetics material to offspring, resulting in Genetic diversity....
  • Zygote intrafallopian transfer
    Zygote intrafallopian transfer

    Zygote intrafallopian transfer is an infertility treatment where a blockage in the fallopian tubes prevents the normal binding of sperm to the egg....
  • Twin Zygosity
    Twin

    Twins are two offspring resulting from the same pregnancy, usually childbirth in close succession. They can be the same or different sex. Twins can either be monozygotic or dizygotic ....
  • Proembryo
    Proembryo

    Proembryo, or pro-embryo, is a botany term that has been used for centuries, to denote the series of cells that are formed after fertilization within the ovule of a flowering plant, before formation of the Plant_embryogenesis....