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Embryonic age: Week nr 1. 0 (whole) weeks old. 1–7 days from fertilization. Fertilization of the ovum to form a new human organism, the human zygote. (day 1 of fertilization [1]) The zygote undergoes mitotic cellular divisions, but does not increase in size. This mitosis is also known as cleavage. A hollow cavity forms marking the blastocyst ...
Human fertilization is the union of an egg and sperm, occurring primarily in the ampulla of the fallopian tube. [1] The result of this union leads to the production of a fertilized egg called a zygote, initiating embryonic development. Scientists discovered the dynamics of human fertilization in the 19th century. [2]
Human embryology is the study of this development during the first eight weeks after fertilization. The normal period of gestation (pregnancy) is about nine months or 36 weeks. The germinal stage refers to the time from fertilization through the development of the early embryo until implantation is completed in the uterus.
Human sexual reproduction, to produce offspring, begins with fertilization. Successful reproduction typically involves sexual intercourse between a healthy, sexually mature and fertile male and female. [1] During sexual intercourse, sperm cells are ejaculated into the vagina through the penis, resulting in fertilization of an ovum to form a ...
In biological terms, human development entails growth from a one-celled zygote to an adult human being. Fertilization occurs when the sperm cell successfully enters and fuses with an egg cell . [2] 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.
In the whole cycle, zygotes are the only diploid cell; mitosis occurs only in the haploid phase. The individuals or cells as a result of mitosis are haplonts, hence this life cycle is also called haplontic life cycle. Haplonts are: In archaeplastidans: some green algae (e.g., Chlamydomonas, Zygnema, Chara) [8] [9]
In human pregnancy, prenatal development is also called antenatal development. The development of the human embryo follows fertilization , and continues 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 .
Asymmetric division is a process of mitosis in which one oogonium divides unequally to produce one daughter cell that will eventually become an oocyte through the process of oogenesis, and one daughter cell that is an identical oogonium to the parent cell.