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An ovum (plural '''ova''') is a Female sex cell or Gamete . The word is derived from Latin , meaning Egg or Egg Cell . Both Animal s and Seed Plant s have ova. The term '''ovule''' is used for the ovum of seed plants and for the young ovum of an animal. In some plants, such as Algae , it is also called '''oosphere'''. In higher animals, ova are produced by female Gonad s (sexual glands) called Ovaries and all of them are present at birth in Mammal s, and mature via Oogenesis . In the Oviparous animals (all Bird s, most Fish es, Amphibians and Reptile s) the ova develop protective layers and pass through the Oviduct to the outside of the body. They are Fertilized by male Sperm either inside the female body (as in birds), or outside (as in many fishes). After fertilization, an Embryo develops, nourished by nutrients contained in the egg. It then hatches from the egg, outside the mother's body. See Egg (biology) for a discussion of eggs of oviparous animals. The egg cell's Cytoplasm and Mitochondria (and Chloroplast s in plants) are the sole means of the egg being able to reproduce by Mitosis and eventually form a Blastocyst after fertilisation, and the sperm are often too small to contribute anything physical except DNA and its own mitochondria gets destroyed by the egg. The egg is thus the sole provider of such Endosymbiotic Organelle s, including mitochondria and chloroplasts within the cytoplasm, especially since these cannot be produced with nuclear DNA alone and must be manufactured from DNA within existing organelles of their type (such as Mitochondrial DNA ) - this is important in Mitochondrial Genetics and can be used to trace maternal and paternal Ancestry , especially as plants contain chloroplasts as well. In the Viviparous animals (which include Human s and all other placental Mammal s), the ovum is fertilized inside the female body, and the embryo then develops inside the Uterus until it is born. It receives nutrition directly from the mother. The ovum is the largest Cell in the human body, typically visible to the naked eye without the aid of a Microscope or other magnification device. There is an intermediate form, the s use this technique. SEE ALSO
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