Search results
Results From The WOW.Com Content Network
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.
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 ...
The process of meiosis in females occurs during oogenesis, and differs from the typical meiosis in that it features a long period of meiotic arrest known as the dictyate stage and lacks the assistance of centrosomes. [53] [54] In males, meiosis occurs during spermatogenesis in the seminiferous tubules of the testicles.
Due to their structural differences, eukaryotic and prokaryotic cells do not divide in the same way. Also, the pattern of cell division that transforms eukaryotic stem cells into gametes (sperm cells in males or egg cells in females), termed meiosis, is different from that of the division of somatic cells in the body. Cell division over 42.
In both males and females, the sex organs consist of two structures: the internal genitalia and the external genitalia. In males, the gonads are the testicles and in females, they are the ovaries . These are the organs that produce gametes (egg and sperm), the reproductive cells that will eventually meet to form the fertilized egg ( zygote ).
The model organism Caenorhabditis elegans—a nematode frequently used in biological research—is one such organism. Most spiders have a variation of the XO system in which males have two different X chromosomes (X 1 X 2 O), while females have a pair of X 1 chromosomes and a pair of X 2 chromosomes (X 1 X 1 X 2 X 2). [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 female or male, or both. [2] There are also some species in which only one sex is present, temporarily or permanently.
Meiosis generates genetic variation in the diploid cell, in part by the exchange of genetic information between the pairs of chromosomes after they align (recombination). Thus, on this view, [28] an advantage of meiosis is that it facilitates the generation of genomic diversity among progeny, allowing adaptation to adverse changes in the ...