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Hermaphrodite
A hermaphrodite () is a sexually reproducing organism that produces both male and female gametes. Animal species in which individuals are either male or female are gonochoric, which is the opposite of hermaphroditic. The individuals of many taxonomic groups of animals, primarily invertebrates, are hermaphrodites, capable of producing viable gametes of both sexes. In the great majority of tunicates, mollusks, and earthworms, hermaphroditism is a normal condition, enabling a form of sexual reproduction in which either partner can act as the female or male. Hermaphroditism is also found in some fish species, but is rare in other vertebrate groups. Most hermaphroditic species exhibit some degree of self-fertilization. The distribution of self-fertilization rates among animals is similar to that of plants, suggesting that similar pressures are operating to direct the evolution of selfing in animals and plants. A rough estimate of the number of hermaphroditic animal species ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Androdioecy
Androdioecy is a reproductive system characterized by the coexistence of males and hermaphrodites. Androdioecy is rare in comparison with the other major reproductive systems: dioecy, gynodioecy and hermaphroditism. In animals, androdioecy has been considered a stepping stone in the transition from dioecy to hermaphroditism, and vice versa. Androdioecy, trioecy and gynodioecy are sometimes referred to as a mixed mating systems. Androdioecy is a dimorphic sexual system in plants comparable with gynodioecy and dioecy. Evolution of androdioecy The fitness requirements for androdioecy to arise and sustain itself are theoretically so improbable that it was long considered that such systems do not exist. Particularly, males and hermaphrodites have to have the same fitness, in other words produce the same number of offspring, in order to be maintained. However, males only have offspring by fertilizing eggs or ovules of hermaphrodites, while hermaphrodites have offspring both th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gynodioecy
Gynodioecy is a rare breeding system that is found in certain flowering plant species in which female and hermaphroditic plants coexist within a population. Gynodioecy is the evolutionary intermediate between hermaphroditism (exhibiting both female and male parts) and dioecy (having two distinct morphs: male and female). Gynodioecy is sometimes considered a mixed mating system comparable with trioecy and androdioecy. It is also considered a dimorphic sexual system alongside dioecy and androdioecy. Gynodioecy occurs as a result of transmission of nuclear (nuclear male sterility) or, more commonly, extra-nuclear (e.g. cytoplasmic male sterility) mutated alleles, which prevents pollen production, while keeping the female reproductive parts intact; other members of the species population don't inherit the mutated alleles, thus remaining hermaphrodites. In some cases, a combination of both nuclear and extra-nuclear mechanisms is observed in determining the sterile phenotype ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ovotesticular Syndrome
Ovotesticular syndrome (also known as ovotesticular disorder or OT-DSD) is a rare congenital condition where an individual is born with both ovarian and testicular tissue. It is one of the rarest disorders of sex development (DSDs), with only 500 reported cases. Commonly, one or both gonads is an ovotestis containing both types of tissue. Although it is similar in some ways to mixed gonadal dysgenesis, the conditions can be distinguished histologically. Terminology In the past, ovotesticular syndrome was referred to as true hermaphroditism, which is considered outdated as of 2006. The term "true hermaphroditism" was considered very misleading by many medical organizations and by many advocacy groups, as hermaphroditism refers to a species that produces both sperm and ova, something that is impossible in humans. Symptoms Physical * Enlargement of one or both breasts in men (gynecomastia) (present in 75% of cases) * Small phallus midway in size between a clitoris and a pe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sexual System
A sexual system is a distribution of male and female functions across organisms in a species. The terms reproductive system and mating system have also been used as synonyms. Sexual systems play a key role in genetic variation and reproductive success, and may also have led to the origin or extinction of certain species. In flowering plants and animals, sexual reproduction involves meiosis, an adaptive process for repairing damage in the germline DNA transmitted to progeny. The distinctions between different sexual systems is not always clear due to phenotypic plasticity. Interest in sexual systems goes back to Charles Darwin, who found that barnacles include some species that are androdioecious and some that are dioecious. Types of sexual systems Flowering plants may have dimorphic or monomorphic sexual systems. In monomorphic sexual systems, a combination of hermaphrodite, male, and/or female flowers may be present on the same plant. Monomorphic sexual systems inclu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Intersex Society Of North America
The Intersex Society of North America (ISNA) was a non-profit advocacy group founded in 1993 by Cheryl Chase (activist), Cheryl Chase to end shame, secrecy, and unnecessary genital surgeries on intersex people.Matthews, Karen (Oct 22, 2000). Debate Grows Over Using Surgery on Infants with Ambiguous Genitals. ''Los Angeles Times''Murrell, Nancy (October 28, 1998). Intersex group raises questions about genital surgery. ''Miami Herald''Hackford-Peer, Kim (2005). Cheryl Chase Founds the Intersex Society of North America. in ''GLBT History, 1993–2004''; 2005, p28-30, 2p Other notable members included Morgan Holmes, Max Beck, Tiger Devore, Howard (Tiger) Devore, Esther Morris Leidolf and Alice Dreger. The organization closed in June 2008,Staff report (June 28, 2008)Farewell message. via ISNA.org and has been succeeded by a number of health, civil and human rights organizations including interACT. Advocacy Physical integrity and bodily autonomy ISNA stated that newborn intersex genit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fish Reproduction
Fish reproductive organs include testicle, testes and ovary, ovaries. In most species, gonads are Bilateria, paired organs of similar size, which can be partially or totally fused. There may also be a range of secondary organs that increase reproductive fitness. The genital papilla is a small, fleshy tube behind the anus in some fishes, from which the sperm or eggs are released; the sex of a fish can often be determined by the shape of its papilla. Anatomy Testes Most male fish have two testes of similar size. In the case of sharks, the testes on the right side is usually larger. The primitive jawless fish have only a single testis, located in the midline of the body, although even this forms from the fusion of paired structures in the embryo. Under a tough membranous shell, the tunica albuginea (testicles), tunica albuginea, the testis of some teleost fish, contains very fine coiled tubes called seminiferous tubules. The tubules are lined with a layer of cells (germ cells) th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gonochorism
In biology, gonochorism is a sexual system where there are two Sex, sexes and each individual organism is either male or female. The term gonochorism is usually applied in animal species, the vast majority of which are gonochoric. Gonochorism contrasts with simultaneous hermaphroditism but it may be hard to tell if a species is gonochoric or Sequential hermaphroditism, sequentially hermaphroditic e.g. parrotfish, ''Patella ferruginea''. However, in gonochoric species individuals remain either male or female throughout their lives. Species that reproduce by Thelytokous, thelytokous parthenogenesis and do not have males can still be classified as gonochoric. Terminology The term is derived from Greek language, Greek ''gone'' 'generation' + ''chorizein'' 'to separate'. The term gonochorism originally came from German ''Gonochorismus''. Gonochorism is also referred to as unisexualism or gonochory. Evolution Gonochorism has Convergent evolution, evolved independently multiple ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hermaphroditus
In Greek mythology, Hermaphroditus (; , ) was a child of Aphrodite and Hermes. According to Ovid, he was born a remarkably beautiful boy whom the naiad Salmacis attempted to rape and prayed to be united with forever. A god, in answer to her prayer, merged their two forms into one and transformed him into a hermaphrodite. His name is compounded of his parents' names, Hermes and Aphrodite. Because Hermaphroditus was a child of Hermes, and consequently a great-grandchild of Atlas (Hermes's mother Maia was the daughter of Atlas), he is sometimes called Atlantiades (). Symbolism Hermaphroditus, the two-sexed child of Aphrodite and Hermes (Venus and Mercury), had long been a symbol of androgyny or effeminacy, and was portrayed in Greco-Roman art as a female figure with male genitals. Theophrastus's account also suggests a link between Hermaphroditus and the institution of marriage. The reference to the fourth day of the month is telling (see Literature section below): this is the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Female
An organism's sex is female ( symbol: ♀) if it produces the ovum (egg cell), the type of gamete (sex cell) that fuses with the male gamete (sperm cell) during sexual reproduction. A female has larger gametes than a male. Females and males are results of the anisogamous reproduction system, wherein gametes are of different sizes (unlike isogamy where they are the same size). The exact mechanism of female gamete evolution remains unknown. In species that have males and females, sex-determination may be based on either sex chromosomes, or environmental conditions. Most female mammals, including female humans, have two X chromosomes. Characteristics of organisms with a female sex vary between different species, having different female reproductive systems, with some species showing characteristics secondary to the reproductive system, as with mammary glands in mammals. In humans, the word ''female'' can also be used to refer to gender in the social sense of gen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Trioecy
Trioecy , also spelled triecy, is a sexual system characterized by the coexistence of males, females, and hermaphrodites. It has been found in both plants and animals. Like androdioecy and gynodioecy, trioecy is a mixed mating systems. Terminology Trioecy is also called tridioecy and subdioecy . The term trioecy comes from the Neo-Latin word '' Trioecia'', a former order of trioecious plants. Evolution of trioecy Trioecy may be an unstable transient state associated with evolutionary transitioning from gynodioecy to dioecy. In brachiopod species, trioecy usually breaks into androdioecy or gynodioecy. Other studies show that trioecious populations originated from gonochoristic ancestors which were invaded by a mutant selfing hermaphrodite, creating a trioecious population. It has been suggested that chromosomal duplication plays an important part in the evolution of trioecy. But one study found that trioecy can be stable under nucleocytoplasmic sex determination. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sexual Reproduction
Sexual reproduction is a type of reproduction that involves a complex life cycle in which a gamete ( haploid reproductive cells, such as a sperm or egg cell) with a single set of chromosomes combines with another gamete to produce a zygote that develops into an organism composed of cells with two sets of chromosomes ( diploid). This is typical in animals, though the number of chromosome sets and how that number changes in sexual reproduction varies, especially among plants, fungi, and other eukaryotes. In placental mammals, sperm cells exit the penis through the male urethra and enter the vagina during copulation, while egg cells enter the uterus through the oviduct. Other vertebrates of both sexes possess a cloaca for the release of sperm or egg cells. Sexual reproduction is the most common life cycle in multicellular eukaryotes, such as animals, fungi and plants. Sexual reproduction also occurs in some unicellular eukaryotes. Sexual reproduction does not occur in pro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Male
Male (Planet symbols, symbol: ♂) is the sex of an organism that produces the gamete (sex cell) known as sperm, which fuses with the larger female gamete, or Egg cell, ovum, in the process of fertilisation. A male organism cannot sexual reproduction, reproduce sexually without access to at least one ovum from a female, but some organisms can reproduce both sexually and Asexual reproduction, asexually. Most male mammals, including male humans, have a Y chromosome, which codes for the production of larger amounts of testosterone to develop male reproductive organs. In humans, the word ''male'' can also be used to refer to gender, in the social sense of gender role or gender identity. Overview The existence of separate sexes has evolved independently at different times and in different lineage (evolution), lineages, an example of convergent evolution. The repeated pattern is sexual reproduction in isogamy, isogamous species with two or more mating types with gametes of identic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
