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Overview of chromatides' and chromosomes' distribution within the mitotic and meiotic cycle of a male human cell. Meiosis occurs in all animals and plants. The result, the production of gametes with half the number of chromosomes as the parent cell, is the same, but the detailed process is different. In animals, meiosis produces gametes directly.
Female mammals and birds are born possessing all the oocytes needed for future ovulations, and these oocytes are arrested at the prophase I stage of meiosis. [26] In humans, as an example, oocytes are formed between three and four months of gestation within the fetus and are therefore present at birth.
Animals have life cycles with a single diploid multicellular phase that produces haploid gametes directly by meiosis. Male gametes are called sperm, and female gametes are called eggs or ova. In animals, fertilization of the ovum by a sperm results in the formation of a diploid zygote that develops by repeated mitotic divisions into a diploid ...
Oogenesis, the process of female gamete formation in animals, involves meiosis (including meiotic recombination) of a diploid primary oocyte to produce a haploid ovum. Spermatogenesis, the process of male gamete formation in animals, involves meiosis in a diploid primary spermatocyte to produce haploid spermatozoa. In animals, ova are produced ...
Male or female gametophyte-producing cells diverge from the reproductive meristem, a totipotent clump of developing cells in the adult plant that creates all the flower's features (both sexual and asexual structures). Second, meiosis is followed by mitotic divisions and differentiation to create the gametes.
The male and female are the only sexually mature fish to reproduce. Clownfish are protandrous hermaphrodites, which means after they mature into males, they eventually can transform into females. They develop undifferentiated until they are needed to fill a certain role in their environment, i.e., if they receive the social and environmental ...
In humans and many other species of animals, the father determines the sex of the child. In the XY sex-determination system, the female-provided ovum contributes an X chromosome and the male-provided sperm contributes either an X chromosome or a Y chromosome, resulting in female (XX) or male (XY) offspring, respectively.
Garden snails mating. A hermaphrodite (/ h ər ˈ m æ f r ə ˌ d aɪ t /) is a sexually reproducing organism that produces both male and female gametes. [1] Animal species in which individuals are either male or female are gonochoric, which is the opposite of hermaphroditic.