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For instance, in birds, male and female somatic cells may exhibit intrinsic differences due to CASI, but the extent to which these differences manifest in tissues can be influenced by circulating hormones such as estrogen and testosterone. Hormones act as amplifiers, enhancing or suppressing sex-specific characteristics that are intrinsically ...
In humans, a single transverse palmar crease is a single crease that extends across the palm of the hand, formed by the fusion of the two palmar creases.Although it is found more frequently in persons with several abnormal medical conditions, it is not predictive of any of these conditions since it is also found in persons with no abnormal medical conditions.
Anisogamy is the form of sexual reproduction that involves the union or fusion of two gametes which differ in size and/or form. [12] The smaller gamete is considered to be male (a sperm cell), whereas the larger gamete is regarded as female (typically an egg cell, if non-motile).
The lack of male sex hormones gives rise to female sex cords and subsequent genitalia differentiation, rather than a presence of female sex hormones. [2] After inducing female sex cord formation, coordination between multiple genes ( Bmp, Pax2, Lim1, and Wnt4 in mice) is required for Müllerian duct development. [ 2 ]
The ova, which are the female sex cells, are much larger than the spermatozoon and are normally formed within the ovaries of the female fetus before birth. They are mostly fixed in location within the ovary until their transit to the uterus, and contain nutrients for the later zygote and embryo .
In contrast, the flagella of female antennae lack these trichoid sensilla projections that make the male antennae appear to be larger and more feather-like. Each trichoid sensilla is innervated by two male specific olfactory receptor cells, with each cell being tuned (most sensitive) to one of two major chemical components of the pheromone. [5]
By and large, a male's potential reproductive success is limited by the number of females he mates with, whereas a female's potential reproductive success is limited by how many eggs she can produce. According to Bateman's principle, this results in sexual selection , in which males compete with each other, and females become choosy in which ...
The reverse is true for the Müllerian duct, as it essentially disappears in the male reproductive system and forms the fallopian tubes, uterus, and vagina in the female system. In both sexes, the gonads go on to form the testes and ovaries; because they are derived from the same undeveloped structure, they are considered homologous organs.