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The mitotic index is a measure of cellular proliferation. [1] It is defined as the percentage of cells undergoing mitosis in a given population of cells. Mitosis is the division of somatic cells into two daughter cells. Durations of the cell cycle and mitosis vary in different cell types. An elevated mitotic index indicates more cells are dividing.
Mitotic indexing is the oldest method of assessing proliferation and is determined by counting the number of mitotic figures (cells undergoing mitosis) through a light microscope on H&E stained sections. It is usually expressed as the number of cells per microscopic field.
In histopathology, the mitosis rate (mitotic count or mitotic index) is an important parameter in various types of tissue samples, for diagnosis as well as to further specify the aggressiveness of tumors. For example, there is routinely a quantification of mitotic count in breast cancer classification. [74]
Some jurisdictions further subdivide agricultural zones to distinguish industrial farming from uses like rural residence farms and retirement farms on large lots. [3] One example of such zoning is the Agricultural Reserve in Montgomery County, Maryland. The reserve was established in 1980 to preserve farmland and rural space. [4]
An agroecosystem can be seen as not restricted to the immediate site of agricultural activity (e.g. the farm). That is, it includes the region that is impacted by this activity, usually by changes to the complexity of species assemblages and energy flows , as well as to the net nutrient balance .
Prior to implantation, the embryo remains in a protein shell, the zona pellucida, and undergoes a series of rapid mitotic cell divisions called cleavage. [3] A week after fertilization the embryo still has not grown in size, but hatches from the zona pellucida and adheres to the lining of the mother's uterus.
In general, nondisjunction can occur in any form of cell division that involves ordered distribution of chromosomal material. Higher animals have three distinct forms of such cell divisions: Meiosis I and meiosis II are specialized forms of cell division occurring during generation of gametes (eggs and sperm) for sexual reproduction, mitosis is the form of cell division used by all other cells ...
The mitotic spindle checkpoint verifies that all the chromosomes are aligned properly on the metaphase plate and prevents premature entry into anaphase. Chromosomes lined up on the metaphase plate. Two views with the metaphase plate rotated 60°. Stages of early mitosis in a vertebrate cell with micrographs of chromatids