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Formation of the corpus luteum: From the remaining structures of the follicle, the corpus luteum is formed. At first, there is a clot, which is then replaced by loose connective tissue; the cells that form solid cords are follicular cells and cells of the outer theca (Tecali lutein cells) and internal ( granulosa cells ).
Polar body twinning is a hypothesized form of twinning in meiosis, where one or more polar bodies do not disintegrate and are fertilized by sperm. [2] Twinning would occur, in principle, if the egg cell and a polar body were both fertilized by separate sperms.
Each primary oocyte divides twice in meiosis, unequally in each case. The first division produces a daughter cell, and a much smaller polar body which may or may not undergo a second division. In meiosis II, division of the daughter cell produces a second polar body, and a single haploid cell, which enlarges to become an ovum. Therefore, in ...
The secondary oocyte continues the second stage of meiosis (meiosis II), and the daughter cells are one ootid and one polar body. Secondary oocytes are the immature ovum shortly after ovulation, to fertilization, where it turns into an ootid. Thus, the time as a secondary oocyte is measured in days.
In developmental biology, left-right asymmetry (LR asymmetry) is the process in early embryonic development that breaks the normal symmetry in the bilateral embryo.In vertebrates, left-right asymmetry is established early in development at a structure called the left-right organizer (the name of which varies between species) and leads to activation of different signalling pathways on the left ...
One sperm fertilizes the egg cell and the other sperm fuses with the two polar nuclei of the large central cell of the megagametophyte. The haploid sperm and haploid egg fuse to form a diploid zygote, the process being called syngamy , while the other sperm and the diploid central cell fuse to form a triploid primary endosperm cell (triple fusion).
This results in a mature haploid ovum and the release of a polar body. [22] The nucleus of the oocyte is called a pronucleus in this process, to distinguish it from the nuclei that are the result of fertilization. Drawing of an ovum. The sperm's tail and mitochondria degenerate with the formation of the male pronucleus. This is why all ...
The formation of the female egg is asymmetrical, while the formation of the male sperm is symmetrical. Typically in a female mammal, meiosis starts with one diploid cell and becomes one haploid ovum and typically two polar bodies, however one may later divide to form a third polar body. [4]