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A gamete is a haploid cell that fuses with another haploid cell during fertilization in organisms that reproduce sexually. Gametes are an organism's reproductive cells, also referred to as sex cells. The name gamete was introduced by the German cytologist Eduard Strasburger.
Sex is the trait that determines whether a sexually reproducing organism produces male or female gametes. During sexual reproduction, a male and a female gamete fuse to form a zygote, which develops into an offspring that inherits traits from each parent. By convention, organisms that produce smaller, more mobile gametes are called male, while organisms that produce produce larger, non-mobile gametes are called female. An organism that produces both types of gamete is hermaphrodite.
The XY sex-determination system is a sex-determination system used to classify many mammals, including humans, some insects (Drosophila), some snakes, some fish (guppies), and some plants. In this system, the sex of an individual is determined by a pair of sex chromosomes. In most cases, females have two of the same kind of sex chromosome (XX), and are called the homogametic sex. Males have two different kinds of sex chromosomes (XY), and are called the heterogametic sex.
A sex-determination system is a biological system that determines the development of sexual characteristics in an organism. Most organisms that create their offspring using sexual reproduction have two common sexes and a few less common intersex variations.
Caenorhabditis elegans is a free-living transparent nematode about 1 mm in length that lives in temperate soil environments. It is the type species of its genus. The name is a blend of the Greek caeno- (recent), rhabditis (rod-like) and Latin elegans (elegant). In 1900, Maupas initially named it Rhabditides elegans. Osche placed it in the subgenus Caenorhabditis in 1952, and in 1955, Dougherty raised Caenorhabditis to the status of genus.
The Y chromosome is one of two sex chromosomes in therian mammals and other organisms. Along with the X chromosome, it is part of the XY sex-determination system, in which the Y is the sex-determining because it is the presence or absence of Y chromosome that determines the male or female sex of offspring produced in sexual reproduction. In mammals, the Y chromosome contains the SRY gene, which triggers development of male gonads. The Y chromosome is passed only from male parents to male offspring.
Sexual differentiation is the process of development of the sex differences between males and females from an undifferentiated zygote. Sex determination is often distinct from sex differentiation; sex determination is the designation for the development stage towards either male or female, while sex differentiation is the pathway towards the development of the phenotype.
Sex-determining region Y protein (SRY), or testis-determining factor (TDF), is a DNA-binding protein encoded by the SRY gene that is responsible for the initiation of male sex determination in therian mammals. SRY is an intronless sex-determining gene on the Y chromosome. Mutations in this gene lead to a range of disorders of sex development with varying effects on an individual's phenotype and genotype.
Corbett v Corbett (otherwise Ashley) is a 1970 family law divorce case heard between November and December 1969 by the High Court of England and Wales in which Arthur Corbett sought annulment of his marriage to April Ashley. Corbett (the husband) had known at the time of the wedding that Ashley (the wife) had been registered male at birth and had undertaken sex-reassignment surgery. However, after the relationship had broken down, Corbett sought to end the marriage, his legal ground for doing so being that the marriage had been invalid, as Ashley was of the male sex.
A polyphenic trait is a trait for which multiple, discrete phenotypes can arise from a single genotype as a result of differing environmental conditions. It is therefore a special case of phenotypic plasticity.
Genetic analysis is the overall process of studying and researching in fields of science that involve genetics and molecular biology. There are a number of applications that are developed from this research, and these are also considered parts of the process. The base system of analysis revolves around general genetics. Basic studies include identification of genes and inherited disorders. This research has been conducted for centuries on both a large-scale physical observation basis and on a more microscopic scale. Genetic analysis can be used generally to describe methods both used in and resulting from the sciences of genetics and molecular biology, or to applications resulting from this research.
Gonadal dysgenesis is classified as any congenital developmental disorder of the reproductive system in humans. It is atypical development of gonads in an embryo,. One type of gonadal dysgenesis is the development of functionless, fibrous tissue, termed streak gonads, instead of reproductive tissue. Streak gonads are a form of aplasia, resulting in hormonal failure that manifests as sexual infantism and infertility, with no initiation of puberty and secondary sex characteristics.
Sexual differentiation in humans is the process of development of sex differences in humans. It is defined as the development of phenotypic structures consequent to the action of hormones produced following gonadal determination. Sexual differentiation includes development of different genitalia and the internal genital tracts and body hair plays a role in sex identification.
Temperature-dependent sex determination (TSD) is a type of environmental sex determination in which the temperatures experienced during embryonic/larval development determine the sex of the offspring. It is observed in reptiles and teleost fish, with some reports of it occurring in species of shrimp. TSD differs from the chromosomal sex-determination systems common among vertebrates. It is the most studied type of environmental sex determination (ESD). Some other conditions, e.g. density, pH, and environmental background color, are also observed to alter sex ratio, which could be classified either as temperature-dependent sex determination or temperature-dependent sex differentiation, depending on the involved mechanisms. As sex-determining mechanisms, TSD and genetic sex determination (GSD) should be considered in an equivalent manner, which can lead to reconsidering the status of fish species that are claimed to have TSD when submitted to extreme temperatures instead of the temperature experienced during development in the wild, since changes in sex ratio with temperature variation are ecologically and evolutionally relevant.
The development of fishes is unique in some specific aspects compared to the development of other animals.
An organism's sex is female if it produces the ovum, the type of gamete that fuses with the male gamete during sexual reproduction.
The ZO sex-determination system is a system that determines the sex of offspring in several moths. In those species, there is one sex chromosome, Z. Males have two Z chromosomes, whereas females have one Z. Males are ZZ, while females are ZO.
Sex reversal is a biological process whereby the pathway directed towards the already determined-sex fate is flipped towards the opposite sex, creating a discordance between the primary sex fate and the sex phenotype expressed. The process of sex reversal occurs during embryonic development or before gonad differentiation. In GSD species, sex reversal means that the sexual phenotype is discordant with the genetic/chromosomal sex. In TSD species, sex reversal means that the temperature/conditions that usually trigger the differentiation towards one sexual phenotype are producing the opposite sexual phenotype.
Jennifer Ann Marshall Graves is an Australian geneticist. She is Distinguished Professor within the La Trobe Institute for Molecular Science, La Trobe University, Australia and Professor Emeritus of the Australian National University.
Four Core Genotypes (FCG) mice are laboratory mice produced by genetic engineering that allow biomedical researchers to determine if a sex difference in phenotype is caused by effects of gonadal hormones or sex chromosome genes. The four genotypes include XX and XY mice with ovaries, and XX and XY mice with testes. The comparison of XX and XY mice with the same type of gonad reveals sex differences in phenotypes that are caused by sex chromosome genes. The comparison of mice with different gonads but the same sex chromosomes reveals sex differences in phenotypes that are caused by gonadal hormones.
References
- ↑ Gilbert, Scott F.; Tyler, Mary S.; Kozlowski, Ronald N. (2000). Developmental biology (6. ed.). Sunderland, Mass: Sinauer Assoc. ISBN 978-0878932436.
- ↑ Shendure, Jay; Balasubramanian, Shankar; Church, George M.; Gilbert, Walter; Rogers, Jane; Schloss, Jeffery A.; Waterston, Robert H. (October 2017). "DNA sequencing at 40: past, present and future". Nature. 550 (7676): 345–353. Bibcode:2017Natur.550..345S. doi:10.1038/nature24286. PMID 29019985. S2CID 205261180.
- ↑ Gilbert, Scott F.; Tyler, Mary S.; Kozlowski, Ronald N. (2000). Developmental biology (6. ed.). Sunderland, Mass: Sinauer Assoc. ISBN 978-0878932436.
- ↑ Alpert, Ash B.; Ruddick, Roman; Manzano, Charlie (24 May 2021). "Rethinking sex-assigned-at-birth questions". BMJ. 373: n1261. doi:10.1136/bmj.n1261. PMID 34031025. S2CID 235171745.
- ↑ Alpert, Ash B.; Ruddick, Roman; Manzano, Charlie (24 May 2021). "Rethinking sex-assigned-at-birth questions". BMJ. 373: n1261. doi:10.1136/bmj.n1261. PMID 34031025. S2CID 235171745.
- ↑ "Google Books Ngram Viewer". books.google.com.
- ↑ "Google Books Ngram Viewer". books.google.com.