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Drawing of the head of a four-week-old human embryo. From Gray's Anatomy. Embryo drawing is the illustration of embryos in their developmental sequence. In plants and animals, an embryo develops from a zygote, the single cell that results when an egg and sperm fuse during fertilization. In animals, the zygote divides repeatedly to form a ball ...
During oocyte development, high metaphase promoting factor (MPF) activity causes mammalian oocytes to arrest at the metaphase II stage until fertilization by a sperm. The fertilization event causes intracellular calcium oscillations, and targeted degradation of cyclin B, a regulatory subunit of MPF, thus permitting the MII-arrested oocyte to ...
This is an accepted version of this page This is the latest accepted revision, reviewed on 16 February 2025. Cell division producing haploid gametes For the figure of speech, see Meiosis (figure of speech). For the process whereby cell nuclei divide to produce two copies of themselves, see Mitosis. For excessive constriction of the pupils, see Miosis. For the parasitic infestation, see Myiasis ...
This interval includes the G 2 phase and metaphase (annotated as "Meta."). During this interval, there is still 2n, but each chromosome will have two copies of each locus, wherein each sister chromatid (chromosome arm) is connected at the centromere, for a total of 4c. [ 17 ]
The second meiotic arrest then occurs after ovulation during metaphase 2 and lasts for a much shorter time than the first arrest. Meiotic arrest occurs mainly due to increased cAMP levels in the oocyte, which regulates key regulator cyclin kinase complex maturation promoting factor (MPF). cGMPs produced by somatic follicular cells further ...
Biological illustration is the use of technical illustration to visually communicate the structure and specific details of biological subjects of study. This can be used to demonstrate anatomy , explain biological functions or interactions, direct surgical procedures, distinguish species, and other applications.
This is achieved by the process of meiosis. In fact, a primary oocyte is, by its biological definition, a cell whose primary function is to divide by the process of meiosis. [16] However, although this process begins at prenatal age, it stops at prophase I.
Also, in metaphase I, the crossed-over arms appear unequal. The aster shouldn't be shown as sun rays; they should have the same appearance as the spindle microtubules (but shorter). The "Homologous chromosomes" label in prophase I should probably point to each of the pairs, the way "Sister chromatids" does in anaphase I.