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  2. XY sex-determination system - Wikipedia

    en.wikipedia.org/wiki/XY_sex-determination_system

    Maternal influences may also be possible that affect sex determination in such a way as to produce fraternal twins equally weighted between one male and one female. [28] The time at which insemination occurs during the estrus cycle has been found to affect the sex ratio of the offspring of humans, cattle, hamsters, and other mammals. [25]

  3. Sexual differentiation - Wikipedia

    en.wikipedia.org/wiki/Sexual_differentiation

    Sexual differentiation is the process of development of the sex differences between males and females from an undifferentiated zygote. [1] [2] 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.

  4. Sex-determination system - Wikipedia

    en.wikipedia.org/wiki/Sex-determination_system

    A sex-determination system is a biological system that determines the development of sexual characteristics in an organism. [1] Most organisms that create their offspring using sexual reproduction have two common sexes, males and females , and in other species, there are hermaphrodites , organisms that can function reproductively as either ...

  5. Shettles method - Wikipedia

    en.wikipedia.org/wiki/Shettles_Method

    The Shettles Method is a child conception idea that is reputed to help determine a baby's sex. It was developed by Landrum B. Shettles in the 1960s and was publicized in the book How to Choose the Sex of Your Baby, coauthored by Shettles and David Rorvik.

  6. Determination of sex - Wikipedia

    en.wikipedia.org/wiki/Determination_of_sex

    [6] [7] The term "sex determination" increased in usage after 1900. [8] In the 1960 and early 70's the term "sex assignment" came into prominent use as a colloquially word for "determination of sex" and "sex determination". "Sex assignment" did not occur in writing prior to the 1960's. It is used ~100 times less frequently than "determination ...

  7. ZW sex-determination system - Wikipedia

    en.wikipedia.org/wiki/ZW_sex-determination_system

    The ZW sex-determination system is a chromosomal system that determines the sex of offspring in birds, some fish and crustaceans such as the giant river prawn, some insects (including butterflies and moths), the schistosome family of flatworms, and some reptiles, e.g. majority of snakes, lacertid lizards and monitors, including Komodo dragons.

  8. XO sex-determination system - Wikipedia

    en.wikipedia.org/wiki/XO_sex-determination_system

    The XO sex-determination system (sometimes referred to as X0 sex-determination system) is a system that some species of insects, arachnids, and mammals (not including humans) use to determine the sex of offspring. In this system, there is only one sex chromosome, referred to as X. Males only have one X chromosome (XO

  9. Pregnancy (mammals) - Wikipedia

    en.wikipedia.org/wiki/Pregnancy_(mammals)

    A pregnant lioness. In mammals , pregnancy is the period of reproduction during which a female carries one or more live offspring from implantation in the uterus through gestation . It begins when a fertilized zygote implants in the female's uterus , and ends once it leaves the uterus.