g phase lasts longer than the mitotic phase or interphase.
which last longer the mitotic phase or interphase?
g phase
the mitotic phase is a relatively short period of the cell cycle. it alternates with the much longer "interphase", where the cell prepares itself for the process of cell division. interphase is divided into three phases: g (first gap), s (synthesis), and g (second gap). during all three parts of interphase, the cell grows by producing proteins and cytoplasmic organelles. however, chromosomes are replicated only during the s phase. thus, a cell grows (g), continues to grow as it duplicates its chromosomes (s), grows more and prepares for mitosis (g), and finally divides (m) before restarting the cycle. all these phases in the cell cycle are highly regulated by cyclins, cyclin-dependent kinases, and other cell cycle proteins. the phases follow one another in strict order and there are "checkpoints" that give the cell cues to proceed from one phase to another. cells may also temporarily or permanently leave the cell cycle and enter g phase to stop dividing. this can occur when cells become overcrowded (density-dependent inhibition) or when they differentiate to carry out specific functions for the organism, as is the case for human heart muscle cells and neurons. some g cells have the ability to re-enter the cell cycle.
mitosis
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. cells in the mitotic phase are identified by the typical appearance of their chromosomes in the cell during the mitotic phase of the cell cycle. usually the number of mitotic figures is expressed as the total number in a defined number of high power fields, such as 10 mitoses in 10 high power fields. since the field of vision area can vary considerably between different microscopes, the exact area of the high power fields should be defined in order to compare results from different studies. accordingly, one of the main problems of counting mitosis has been the reproducibility. thus, the need for standardized methodology and strict protocols is important to achieve reproducible results.
proliferative index