Diseases, Conditions, Syndromes

COVID-19 infection may reduce fertility in men

COVID-19 may negatively affect sperm quality and reduce fertility in men, according to research published in Reproduction. The study indicates that COVID-19 infection can cause increased sperm cell death, inflammation, and ...

Medical research

Nanotechnology prevents premature birth in mouse studies

In a study in mice and human cells, Johns Hopkins Medicine researchers say that they have developed a tiny, yet effective method for preventing premature birth. The vaginally-delivered treatment contains nanosized (billionth ...

Oncology & Cancer

NSD2 enzyme appears to prevent cellular senescence

Researchers from Kumamoto University in Japan have used comprehensive genetic analysis to find that the enzyme NSD2, which is known to regulate the actions of many genes, also works to block cell aging. Their experiments ...

Genetics

New mutations accumulate in reproductive cells of older mice

Older mice have more new mutations—changes in DNA sequence that occur in the individual rather than being inherited from a parent—than younger mice in the genomes of their mitochondria, according to researchers at Penn ...

Medical research

Recurrent UTIs linked to hidden reservoir

Urinary tract infections (UTIs) frequently recur due to bacteria constructing safe havens within the host. While infection is frequently caused by uropathogenic Escherichia coli that originates in the gut, little is known ...

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Gamete

A gamete (from Ancient Greek γαμέτης; translated gamete = wife, gametes = husband) is a cell that fuses with another gamete during fertilization (conception) in organisms that reproduce sexually. In species that produce two morphologically distinct types of gametes, and in which each individual produces only one type, a female is any individual that produces the larger type of gamete — called an ovum (or egg) — and a male produces the smaller tadpole-like type — called a sperm. This is an example of anisogamy or heterogamy, the condition wherein females and males produce gametes of different sizes (this is the case in humans; the human ovum is approximately 20 times larger than the human sperm cell). In contrast, isogamy is the state of gametes from both sexes being the same size and shape, and given arbitrary designators for mating type. The name gamete was introduced by the Austrian biologist Gregor Mendel. Gametes carry half the genetic information of an individual, one chromosome of each type. In humans, an ovum can carry only X chromosome (of the X and Y chromosomes), whereas a sperm can carry either an X or a Y; hence, it has been suggested that males have the control of the sex of any resulting zygote, as the genotype of the sex-determining chromosomes of a male must be XY and a female XX. In other words, due to the presence of the Y chromosome exclusively in the sperm, it is that gamete alone that can determine that an offspring will be a male.

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