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 [o´vum] (pl. o´va) (L.)
the female reproductive or germ cell which after fertilization is capable of developing into a new member of the same species; called also egg. The term is sometimes applied to any stage of the fertilized germ cell during cleavage and even until hatching or birth of the new individual. The human ovum consists of protoplasm that contains some yolk, enclosed by a cell wall consisting of two layers, an outer one (zona pellucida) and an inner, thin one (vitelline membrane). There is a large nucleus (germinal vesicle) within which is a nucleolus (germinal spot). adj., adj o´vular.
centrolecithal ovum one with the yolk concentrated at the center of the egg, surrounded by a peripheral shell of cytoplasm, and with an island of cytoplasm surrounding the nucleus, such as that of an arthropod.
holoblastic ovum one that undergoes total cleavage.
isolecithal ovum one with a small amount of yolk evenly distributed throughout the cytoplasm.
meroblastic ovum one that undergoes partial cleavage.
primitive ovum (primordial ovum) any oocyte very early in its development.
telolecithal ovum one with a comparatively large amount of yolk massed at one pole, such as that of a reptile or bird.
Miller-Keane Encyclopedia and Dictionary of Medicine, Nursing, and Allied Health, Seventh Edition. © 2003 by Saunders, an imprint of Elsevier, Inc. All rights reserved.


, gen.


, pl.


(ō'vŭm, -vī, -vă),
The term ovum is imprecise because it has been variously applied to stages from the primary oocyte to the implanting blastocyst.
See also: oocyte.
[L. egg]
Farlex Partner Medical Dictionary © Farlex 2012


n. pl. ova (ō′və)
The mature female gamete of an animal; an egg.
The American Heritage® Medical Dictionary Copyright © 2007, 2004 by Houghton Mifflin Company. Published by Houghton Mifflin Company. All rights reserved.


A female reproductive cell that has a haploid genetic complement (22 somatic chromosomes and one X chromosome) which, once united with the sperm, is termed a fertilised egg.
Segen's Medical Dictionary. © 2012 Farlex, Inc. All rights reserved.


The female sex cell. When fertilized by a sperm, a gamete or zygote is capable of developing into a new individual of the same species; during maturation, the oocyte, like the sperm, undergoes a halving of its chromosomal complement so that, at its union with the male gamete, the species number of chromosomes (46 in humans) is maintained; yolk contained in the oocyte (ova in nonhuman species) varies greatly in amount and distribution, which influences the pattern of the cleavage divisions. In nonhuman females, the term is ovum.
[G. ōon, egg, + kytos, a hollow (cell)]
Medical Dictionary for the Health Professions and Nursing © Farlex 2012


(o'vum) plural.ova [L., egg]
1. The female reproductive or germ cell.
2. A cell that is capable of developing into a new organism of the same species. Usually fertilization by a spermatozoon is necessary, although in some lower animals ova develop without fertilization (parthenogenesis). See: conception; fertilization; menstrual cycle; menstruation

alecithal ovum

An ovum with a small yolk portion that is distributed throughout the protoplasm. Synonym: isolecithal ovum

centrolecithal ovum

An ovum having a large central food yolk, as in a bird's egg.

holoblastic ovum

An ovum that undergoes complete cleavage, as opposed to partial or meroblastic cleavage.
Enlarge picture

human ovum

The female gamete, required for reproduction. The ovum develops from an oogonium within the graafian follicle of the ovary and matures through the meiotic process of oogenesis. A mature ovum is about 0.13 to 0.14 mm (0.0051 to 0.0055 in) in diameter. At ovulation, the ovum is bounded by a translucent cellular membrane (the zona pellucida), which is connected to a layer of follicular cells (the corona radiata); these cells enclose the cytoplasm, nuclei, and chromatin material. The exact time during which a human ovum is capable of fertilization and further development before degenerating is not known; however, it is probably 24 hr. See: illustration; oogenesis; ovulation

isolecithal ovum

Alecithal ovum.

mature ovum

A secondary oocyte that has completed its second meiotic division as a result of contact with a sperm. The nucleus of the mature ovum becomes the female pronucleus.

meroblastic ovum

An ovum in which only the protoplasmic region undergoes cleavage, characteristic in ova containing a large amount of yolk.

permanent ovum

An ovum ready for fertilization.

primordial ovum

A germ cell that arises very early in the development of the embryo, usually in the yolk sac endoderm, migrates into the urogenital ridge, and is the precursor for the functional gamete.

telolecithal ovum

An ovum in which the yolk is fairly abundant and tends to concentrate in one hemisphere.
Medical Dictionary, © 2009 Farlex and Partners


The female gamete or ovum which, when fertilized by a spermatozoon, can give rise to a new individual. The egg is a very large cell, compared with other body cells, and contains only 23 chromosomes, half the normal number (haploid). Like most other cells ova contain many mitochondria each containing many copies of mitochondrial DNA. This DNA is not present in sperms.
Collins Dictionary of Medicine © Robert M. Youngson 2004, 2005





egg cell

(pl. ova) a functional egg cell of an animal, produced by GAMETOGENESIS. Ova are frequently packed with nutritive yolk granules and are usually immobile (see OOGAMY). The human egg is about 0.14 mm in diameter, which is some 50,000 times larger than the human sperm.
Collins Dictionary of Biology, 3rd ed. © W. G. Hale, V. A. Saunders, J. P. Margham 2005

Ovum (plural: ova)

The reproductive cell of the female, which contains genetic information and participates in the act of fertilization. Also popularly called the egg.
Mentioned in: Infertility
Gale Encyclopedia of Medicine. Copyright 2008 The Gale Group, Inc. All rights reserved.


, pl. ova (ō'vŭm, -vă)
Term is imprecise because it has been variously applied to various stages from the primary oocyte to the implanting blastocyst.
See: oocyte
[L. egg]
Medical Dictionary for the Dental Professions © Farlex 2012

Patient discussion about ovum

Q. Is there any difference between brown eggs and white eggs? My fitness instructor suggested me to have brown eggs instead of white eggs so is there any difference between brown eggs and white eggs?

A. I have to agree with you. Never heard of any difference between the two and it doesnt sound reasonable that one is better to your health than the other...

Q. why the renal doctor told my husband that he needs to eat a dozen of egg a week for protein,how it will help? it won`t afect his cholesterol,also i would like to know what role the protein plays on his treatment and what other foot its rich in protein that he can can take,without causing problems to his health.

A. if i understand correctly, your husband is diabetic. like my grandfather he probably developed a "Diabetic nephropathy" which is a long name to: kidney being destroyed because of blood vessels clotted by diabetes. because of that destruction the kidneys allow protein to go out in the urine. this is a dangerous situation,a protein in the name of "albomin" helps our blood to hold fluids in blood vessels. without it fluid will leave the blood and go to our organs. not a good situation. so he needs a lot of proteins.
here is a list of a 100 protein rich foods:

Q. How can I catch Salmonella? Yesterday I ate a mousse which was made from raw eggs. Could I have caught Salmonella?

A. Salmonella infections usually resolve in 5-7 days and often do not require treatment unless the patient becomes severely dehydrated or the infection spreads from the intestines. Persons with severe diarrhea may require rehydration, often with intravenous fluids (IV). Antibiotics are not usually necessary unless the infection spreads from the intestines.

More discussions about ovum
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