"Cleavage (embryo) In embryology, cleavage is the division of cells in the early embryo. The process follows fertilization, with the transfer being triggered by the activation of a cyclin-dependent kinase complex. The zygotes of many species undergo rapid cell cycles with no significant overall growth, producing a cluster of cells the same size as the original zygote. The different cells derived from cleavage are called blastomeres and form a compact mass called the morula. Cleavage ends with the formation of the blastula. Depending mostly on the amount of yolk in the egg, the cleavage can be holoblastic (total or entire"
"Embryology Embryology (from Greek , ""embryon"", ""the unborn, embryo""; and , ""-logia"") is the branch of biology that studies the prenatal development of gametes (sex cells), fertilization, and development of embryos and fetuses. Additionally, embryology encompasses the study of congenital disorders that occur before birth, known as teratology. Embryology has a long history. Aristotle proposed the currently accepted theory of epigenesis, that organisms develop from seed or egg in a sequence of steps. The alternative theory, preformationism, that organisms develop from pre-existing miniature versions of themselves, however held sway until the 18th century. Modern embryology developed from the work of"
"Embryogenesis Embryogenesis is the process by which the embryo forms and develops. In mammals, the term refers chiefly to early stages of prenatal development, whereas the terms fetus and fetal development describe later stages. Embryogenesis starts with the fertilization of the egg cell (ovum) by a sperm cell, (spermatozoon). Once fertilized, the ovum is referred to as a zygote, a single diploid cell. The zygote undergoes mitotic divisions with no significant growth (a process known as cleavage) and cellular differentiation, leading to development of a multicellular embryo. Although embryogenesis occurs in both animal and plant development, this article addresses the"
"of the embryo that occurs during the early stages of development. In biological terms, human development entails growth from a one-celled zygote to an adult human being. Fertilisation occurs when the sperm cell successfully enters and fuses with an egg cell (ovum). The genetic material of the sperm and egg then combine to form a single cell called a zygote and the germinal stage of prenatal development commences. Embryogenesis covers the first eight weeks of development; at the beginning of the ninth week the embryo is termed a fetus. The germinal stage refers to the time from fertilization through the"
"roles in certain diseases and mutations, and its links to stem cell research. Embryology is the key to Gestational Surrogacy, which is when the sperm of the intended father and egg of intended mother are fused in a lab forming an embryo. This embryo is then put into the surrogate who carries the child to term. Embryology Embryology (from Greek , ""embryon"", ""the unborn, embryo""; and , ""-logia"") is the branch of biology that studies the prenatal development of gametes (sex cells), fertilization, and development of embryos and fetuses. Additionally, embryology encompasses the study of congenital disorders that occur before"
"and later fetus develops during gestation. Prenatal development starts with fertilization, the first stage in embryogenesis which continues in fetal development until birth. Fertilization occurs when the sperm successfully enters the ovum's membrane. The chromosomes of the sperm combine with those of the egg to form a single cell, called a zygote, and the germinal stage of embryogenesis commences. The germinal stage refers to the time from fertilization, through the development of the early embryo, up until implantation. The germinal stage is over at about 10 days of gestation. The zygote contains a full complement of genetic material and develops"
"Development of the human body Human development is the process of growth to maturity. The process begins with fertilisation, where an egg released from the ovary of a female is penetrated by a sperm cell from a male. The egg then lodges in the uterus, where an embryo and later fetus develop until birth. Further growth and development continues after birth, and includes both physical and psychological development, influenced by genetic, hormonal, environmental and other factors. This continues throughout life, through childhood, and adolescence into adulthood. Development before birth, or prenatal development () is the process in which an embryo"
"Human embryogenesis Human embryogenesis refers to the development and formation of the human embryo. It is characterised by the process of cell division and cellular differentiation of the embryo that occurs during the early stages of development. In biological terms, human development entails growth from a one-celled zygote to an adult human being. Fertilisation occurs when the sperm cell successfully enters and fuses with an egg cell (ovum). The genetic material of the sperm and egg then combine to form a single cell called a zygote and the germinal stage of prenatal development commences. Embryogenesis covers the first eight weeks"
"Embryo An embryo is an early stage of development of a multicellular diploid eukaryotic organism. In general, in organisms that reproduce sexually, an embryo develops from a zygote, the single cell resulting from the fertilization of the female egg cell by the male sperm cell. The zygote possesses half the DNA from each of its two parents. In plants, animals, and some protists, the zygote will begin to divide by mitosis to produce a multicellular organism. The result of this process is an embryo. In human pregnancy, a developing fetus is considered as an embryo until the ninth week, fertilization"
"death rates, impaired lung and immune system development. Prenatal development Prenatal development () is the process in which an embryo and later fetus develops during gestation. Prenatal development starts with fertilization, the first stage in embryogenesis which continues in fetal development until birth. In human pregnancy, prenatal development, also known as antenatal development, is the development of the embryo following fertilization, and continued as fetal development. By the end of the tenth week of gestational age the embryo has acquired its basic form and is referred to as a fetus. The next period is that of fetal development where many"
"Prenatal development Prenatal development () is the process in which an embryo and later fetus develops during gestation. Prenatal development starts with fertilization, the first stage in embryogenesis which continues in fetal development until birth. In human pregnancy, prenatal development, also known as antenatal development, is the development of the embryo following fertilization, and continued as fetal development. By the end of the tenth week of gestational age the embryo has acquired its basic form and is referred to as a fetus. The next period is that of fetal development where many organs become fully developed. This fetal period is"
"be passed from the mother to the unborn child at any stage of its development. Hypoxia a condition of inadequate oxygen supply can be a serious consequence of a preterm or premature birth. Human embryogenesis Human embryogenesis refers to the development and formation of the human embryo. It is characterised by the process of cell division and cellular differentiation of the embryo that occurs during the early stages of development. In biological terms, human development entails growth from a one-celled zygote to an adult human being. Fertilisation occurs when the sperm cell successfully enters and fuses with an egg cell"
"based on physiological fetal development, which include blastogenesis, embryonic stage and fetal stage. Blastogenesis is the stage from fertilization to about 2 weeks. The fertilized egg or the zygote becomes a blastocyst where the outer layer and the inner cell mass differentiate to form placenta and the fetus respectively. Implantation occurs at this stage where the blastocyst becomes buried in the endometrium. Embryonic stage is approximately from 2 weeks to 8 weeks. It is also in this stage where the blastocyst develops into an embryo, where all major features of human are present and operational by the end of this"
"a sphere or sheet of cells, also called blastomeres. In a placental mammal, an ovum is fertilized in a fallopian tube through which it travels into the uterus. An embryo is called a fetus at a more advanced stage of development and up until birth or hatching. In humans, this is from the eleventh week of gestation. However, animals which develop in eggs outside the mother's body, are usually referred to as embryos throughout development; e.g. one would refer to a chick embryo, not a ""chick fetus"", even at later stages. During gastrulation the cells of the blastula undergo coordinated"
"age, or eleventh-week gestational age. After this time the embryo is referred to as a fetus. First attested in English in the mid-14c., the word ""embryon"" derives from Medieval Latin ""embryo"", itself from Greek (""embruon""), lit. ""young one"", which is the neuter of (""embruos""), lit. ""growing in"", from ἐν (""en""), ""in"" and βρύω (""bruō""), ""swell, be full""; the proper Latinized form of the Greek term would be ""embryum"". In animals, the development of the zygote into an embryo proceeds through specific recognizable stages of blastula, gastrula, and organogenesis. The blastula stage typically features a fluid-filled cavity, the blastocoel, surrounded by"
"and temporal changes in gene expression, cell growth and cellular differentiation. A nearly identical process occurs in other species, especially among chordates. A fetus is a stage in the human development considered to begin nine weeks after fertilization. In biological terms, however, prenatal development is a continuum, with many defining feature distinguishing an embryo from a fetus. A fetus is also characterized by the presence of all the major body organs, though they will not yet be fully developed and functional and some not yet situated in their final location. The fetus and embryo develop within the uterus, an organ"
"frequently. This together with softwares allows embryologists and clinicans to interpret the embryo development information captured and select embryos for transfer in IVF treatment. Research for an algorithm to select a single embryo that would lead to the best clinical pregnancy outcome is underway. Morphology of the embryo is studied in scientific research and often marked by stages. ""For further details of the processes that occur within each stage, see Human embryogenesis."" 1. Fertilization After the egg is fertilized by the sperm, a zygote (single diploid cell) is formed. At this stage, it should have two pronuclei, one of each"
"that those categories are inaccurate. The illustration shows the ontological status of the preembryo, embryo, and fetus: The colors represent the maternal and paternal genetic contributions. Proembryo Proembryo, or pro-embryo, is a botanical 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 embryo. More recently, this same term has been given a more extensive meaning, with reference to a human conceptus not yet implanted into a uterus. This more recent meaning is synonymous with ""preembryo"" or ""pre-embryo"", and corresponds to"
"develops both into embryonic and extra-embryonic tissue, the latter forming the fetal membranes and the placenta. In humans, the embryo is referred to as a fetus in the later stages of prenatal development. The transition from embryo to fetus is arbitrarily defined as occurring 8 weeks after fertilization. In comparison to the embryo, the fetus has more recognizable external features and a set of progressively developing internal organs. A nearly identical process occurs in other species. Human embryogenesis refers to the development and formation of the human embryo. It is characterised by the process of cell division and cellular differentiation"
"different stages they pass through, and the stage affects the acceptability of the procedure. Prenatal Development outlines these different stages. From conception, when the sperm and egg fuse in the fallopian tube, until week 5 of the pregnancy, it is referred to as the zygote. From week 5 until week 10 of the pregnancy, it is referred to as an embryo. At week 10 in the pregnancy, the embryo becomes a fetus and development of all organ systems and body parts begins. At around the 38-40th week, a fully developed baby will be born. For Islam followers, once the cells"
"Oogenesis Oogenesis, ovogenesis, or oögenesis is the differentiation of the ovum (egg cell) into a cell competent to further development when fertilized. It is developed from the primary oocyte by maturation. Oogenesis is initiated in the embryonic stage. In mammals, the first part of oogenesis starts in the germinal epithelium, which gives rise to the development of ovarian follicles, the functional unit of the ovary. Oogenesis consists of several sub-processes: oocytogenesis, ootidogenesis, and finally maturation to form an ovum (oogenesis proper). Folliculogenesis is a separate sub-process that accompanies and supports all three oogenetic sub-processes. Oogonium —(Oocytogenesis)—> Primary Oocyte —(Meiosis I)—>"
"Bootstrapping (biology) The idea of bootstrapping is significant in a number of fields in the biological sciences. The process by which a fertilised ovum develops into an embryo, particularly the way in which the nuclear genome is expressed differently in its various cells as these differentiate, is one example of bootstrapping. The evolution of progressively better adapted organs through natural selection in a lineage of organisms is another. Some biologists, including Graham Cairns-Smith, believe that the origin of life itself may have been a bootstrap process as one or more systems of biological information storage formed the foundation for successor"
"Human fertilization Human fertilization is the union of a human egg and sperm, usually occurring in the ampulla of the fallopian tube. The result of this union is the production of a zygote cell, or fertilized egg, initiating prenatal development. Scientists discovered the dynamics of human fertilization in the nineteenth century. The process of fertilization involves a sperm fusing with an ovum. The most common sequence begins with ejaculation during copulation, follows with ovulation, and finishes with fertilization. Various exceptions to this sequence are possible, including artificial insemination, ""in vitro"" fertilization, external ejaculation without copulation, or copulation shortly after ovulation."
"the embryo, as well as cells which begin to differentiate into blood vessels. Endocardial cells begin to form the myocardium. At about 24 days past fertilization, there is a primitive S-shaped tubule heart which begins beating. The flow of fluids throughout the embryo begins at this stage. For mammals the gestation period is the time in which a fetus develops, beginning with fertilization and ending at birth. The duration of this period varies between species. For most species, the amount a fetus grows before birth determines the length of the gestation period. Smaller species normally have a shorter gestation period"
"fertilization process. Human fertilization Human fertilization is the union of a human egg and sperm, usually occurring in the ampulla of the fallopian tube. The result of this union is the production of a zygote cell, or fertilized egg, initiating prenatal development. Scientists discovered the dynamics of human fertilization in the nineteenth century. The process of fertilization involves a sperm fusing with an ovum. The most common sequence begins with ejaculation during copulation, follows with ovulation, and finishes with fertilization. Various exceptions to this sequence are possible, including artificial insemination, ""in vitro"" fertilization, external ejaculation without copulation, or copulation shortly"
"of the egg by the sperm) and continues until the end of the 10th week of gestation (8th week by embryonic age). The period of two weeks from fertilization is also referred to as the germinal stage. The embryo spends the next few days traveling down the Fallopian tube. It starts out as a single cell zygote and then divides several times to form a ball of cells called a morula. Further cellular division is accompanied by the formation of a small cavity between the cells. This stage is called a blastocyst. Up to this point there is no growth"
"into the embryo. Briefly, embryonic development have four stages: the morula stage, the blastula stage, the gastrula stage, and the neurula stage. Prior to implantation, the embryo remains in a protein shell, the zona pellucida, and undergoes a series of cell divisions, called mitosis. A week after fertilization the embryo still has not grown in size, but hatches from the zona pellucida and adheres to the lining of the mother's uterus. This induces a decidual reaction, wherein the uterine cells proliferate and surround the embryo thus causing it to become embedded within the uterine tissue. The embryo, meanwhile, proliferates and"
"Embryo culture Embryo culture is a component of ""in vitro"" fertilisation where in resultant embryos are allowed to grow for some time in an artificial medium . The duration of embryo culture can be varied, conferring different stages of embryogenesis at embryo transfer. The main stages at which embryo transfer is performed are cleavage stage (day 2 to 4 after co-incubation) or the blastocyst stage (day 5 or 6 after co-incubation). Embryos which reach the day 3 cell stage can be tested for chromosomal or specific genetic defects prior to possible transfer by preimplantation genetic diagnosis (PGD). Embryo culture until"
"stage of gastrulation, when the three germ layers of the embryo form in a process called histogenesis, and the processes of neurulation and organogenesis follow. In comparison to the embryo, the fetus has more recognizable external features and a more complete set of developing organs. The entire process of embryogenesis involves coordinated spatial and temporal changes in gene expression, cell growth and cellular differentiation. A nearly identical process occurs in other species, especially among chordates. Fertilization takes place when the spermatozoon has successfully entered the ovum and the two sets of genetic material carried by the gametes fuse together, resulting"
"Fetus A fetus or foetus (; plural fetuses, feti or foetuses) is the prenatal stage between the embryonic stage and birth . In human development the fetal stage begins from the ninth week after fertilisation (or eleventh week gestational age) and continues until birth. Prenatal development is a continuum, with no clear defining feature distinguishing an embryo from a fetus. However, a fetus is characterized by the presence of all the major body organs, though they will not yet be fully developed and functional and some not yet situated in their final anatomical location. The word ""fetus"" (plural ""fetuses"") is"
"egg within a woman. Since sperm that enters a woman's uterus and then fallopian tubes goes on to fertilize an egg which develops into a fetus or child, the male reproductive system plays no necessary role during the gestation. The concept of fatherhood and family exists in human societies. The study of male reproduction and associated organs is called andrology. In mammals, the hormones that influence sexual differentiation and development are androgens (mainly testosterone), which stimulate later development of the ovary. In the sexually undifferentiated embryo, testosterone stimulates the development of the Wolffian ducts, the penis, and closure of the"
"the father's sperm in a technique called in vitro fertilization (IVF). ""In vitro"" is Latin for ""within glass"". Fertilized eggs are called embryos. As the embryos develop through mitosis, they are separated by sex. Embryos of the desired gender are implanted back in the mother's uterus. Prior to fertilization with IVF, the fertilized eggs can be genetically biopsied with preimplantation genetic diagnosis (PGD) to increase fertilization success. Once an embryo grows to a 6-8 cell size, a small laser incision in the egg membrane (zona pellucida) allows safe removal of one of the cells. Every cell in the embryo contains"
"body of the uterus and into the Fallopian tubes. Fertilization of the egg cell (ovum), usually takes place in one of the Fallopian tubes. Many sperm are released with the possibility of just one sperm cell managing to adhere to and enter the thick protective shell-like layer surrounding the ovum. The first sperm that penetrates fully into the egg donates its genetic material (DNA). The egg then polarizes, repelling any additional sperm. The resulting combination is called a zygote, a new and genetically unique organism. The term ""conception"" refers variably to either fertilization or to formation of the conceptus after"