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The first fossilized evidence of sexual reproduction in eukaryotes is from the Stenian period, about 1.05 billion years old. [19] [20]Biologists studying evolution propose several explanations for the development of sexual reproduction and its maintenance.
The reproductive system of an organism, also known as the genital system, is the biological system made up of all the anatomical organs involved in sexual reproduction.Many non-living substances such as fluids, hormones, and pheromones are also important accessories to the reproductive system. [1]
Labeled anatomy of the human vulva and nearby structures. The vulva is of all of the external parts and tissues and includes the following: [4] Clitoris: an organ located at the top of the vulva.
Asexual reproduction in liverworts: a caducous phylloid germinating. Asexual reproduction is a type of reproduction that does not involve the fusion of gametes or change in the number of chromosomes.
Adolescent health creates a major global burden and has a great deal of additional and diverse complications compared to adult reproductive health such as early pregnancy and parenting issues, difficulties accessing contraception and safe abortions, lack of healthcare access, and high rates of HIV, sexually transmitted infections and mental health issues.
Puberty is the process of physical changes through which a child's body matures into an adult body capable of sexual reproduction.It is initiated by hormonal signals from the brain to the gonads: the ovaries in a female, the testicles in a male.
Part of a series on Sex Biological terms Sexual dimorphism Sexual differentiation Feminization Virilization Sex-determination system XY XO ZW ZO Temperature-dependent Haplodiploidy Heterogametic sex Homogametic sex Sex chromosome X chromosome Y chromosome Sex chromosome anomalies Testis-determining factor Hermaphrodite Sequential hermaphroditism Simultaneous hermaphroditism Intersex (biology ...
Greater sage-grouse at a lek, with multiple males displaying for the less conspicuous females. In sociobiology and behavioural ecology, the term "mating system" is used to describe the ways in which animal societies are structured in relation to sexual behaviour.