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51.2 Gametogenesis and Fertilization
Animals that reproduce sexually are less likely to have moderately deleterious genes.
The hypothesis died and did not reproduce.
Approximately how many times did deleterious mutations persist in the asexually reproducing sexual populations but not in the asexual ones.
Starts with cells called germ cells.
The development of sperm and eggs is similar to the formation of gametes.
In this section, we will look at the differences between the two types of gamete.
In species with separate sexes, males have testes and females have mature haploid sperm cells.
Some animal species result in four gametes from each spermatogonium.
Male diploid (2n) germ cells undergo two meiotic divisions to produce mature haploid sperm.
The head, midpiece, and flagellum of a mature human sperm can be seen in a drawing and scanning electron micrograph.
The process of oogenesis in females, which produces a haploid secondary oocyte that enters but does not complete meiosis II until it is fertilized.
The drawing depicts a secondary oocyte within its follicle, while theSEM shows an isolated human oocyte covered by its zona pellucida and remnants of the cumulus mass.
The structure of a sperm cell is an example of the core concept of biology.
The sperm cell's structural elements are suited for a specific function.
The sperm is capable of fertilization when all three elements are working together.
Each spermatocyte has a different oocyte in it.
The tail mass, also known as the flagellum, is a layer of cells outside of the sperm that provides protection and support.
The tail needs energy to make zona pellucida.
The sperm motile is produced by an outer cellular layer called the theca.
The head region of the sperm contains mones that control oocyte growth.
The nucleus carries the chromosomes.
Important roles in fertilization can be found at the tip of the head.
Fertilization is the process by which the haploid male and female gam on the species are able to reproduce.
Four gametes are produced by spermatogenesis.
The oogenesis begins in the ovary of a female embryo.
The oogonia divide by attracting nearby sperm.
This increases the number of primary oocytes that enter meiosis I but stops the process of respiration within the arrested state after birth.
Meiosis does not resume until the sperm is present.
The time after puberty when a mammal first becomes capable of reproducing by following the concentration of attractants is when the sperm swims.
A polar body is a smaller cell.
The sperm must start in the secondary oocytes but stop at the metaphase in Meiosis II sea urchins.
If sperm are available, the sperm is able to do this.
The second meiotic division doesn't happen if the oocyte doesn't encounter the acrosome.
A diploid zygote is produced when the nucleus is dissolved by these enzymes.
The sperm head ian structure is fused after binding.
The sperm-binding acrosome and the vitelline hydrolytic enzymes that bind to the egg are destroyed by the contents of the cortical 3.
A series of events allow the head of the sperm to bind to the egg.
The vitelline layer of the egg is prevented from being fused by an increased concentration of Ca2+.
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