Diseases, Conditions, Syndromes

New potential therapy for fatty liver disease

In those with fatty liver disease, a person's fat goes to their liver instead of their fat tissue, either because of an absence of fat depots, which is seen in the rare genetic disease lipodystrophy, or because the depots ...

Medical research

Guppy research shows ADHD drugs can affect later generations

By studying guppies, scientists at the University of Toronto and Florida State University found that behaviors affected by methylphenidate hydrochloride (MPH) – the active ingredient in stimulants such as Ritalin and Concerta ...

Cardiology

Aortic condition more deadly in women than in men

Women who experience acute aortic dissection—a spontaneous and catastrophic tear in one of the body's main arteries—not only are older and have more advanced disease than men when they seek medical care, but they also ...

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Male

Male (♂) refers to the sex of an organism, or part of an organism, which produces small mobile gametes, called spermatozoa. Each spermatozoon can fuse with a larger female gamete or ovum, in the process of fertilization. A male cannot reproduce sexually without access to at least one ovum from a female, but some organisms can reproduce both sexually and asexually.

Not all species share a common sex-determination system. In humans and most animals, sex is determined genetically but in other species it can be determined due to social, environmental, or other factors. The existence of two sexes seems to have been selected independently across different evolutionary lineages (see Convergent Evolution). Accordingly, sex is defined operationally across species by the type of gametes produced (ie: spermatozoa vs. ova) and differences between males and females in one lineage are not always predictive of differences in another.

Male/Female dimorphism between organisms or reproductive organs of different sexes is not limited to animals; male gametes are produced by chytrids, diatoms and land plants, among others. In land plants, female and male designate not only the female and male gamete-producing organisms and structures but also the structures of the sporophytes that give rise to male and female plants.

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