What Is Meiotic Interphase?

By Tammie Painter
Cells spend most of their lifetimes in interphase.

To grow, repair and reproduce, cells undergo one of two cell division processes: mitosis or meiosis. Mitosis produces two daughter cells that have the same number of chromosomes as the mother cell. With meiosis, four daughter cells with half the number of chromosomes as the mother cells are produced. Although the process of mitosis and meiosis differs, what occurs during the interphase stage of meiosis is the same as that of mitosis.

Doing Their Job

During the first phase of meiotic interphase -- known as G1 -- cells grow and perform many of their required cellular functions. These functions can include producing proteins and transmitting signals to or receiving signals from other cells. During this phase, the chromosomes are housed within a nuclear membrane.

Doubling Time

Interphase is a time for the cell to prepare for meiosis and part of this preparation involves doubling the number of chromosomes the cell contains. This part of interphase is known as S phase, with the S standing for synthesis. Each chromosome ends up with an identical twin. The twins are joined together in a dense area called a centromere. These joined twin chromosomes are called chromatids. During the S phase, the nuclear envelope is still in place and the chromatids are not distinct. In the cells of plants, the mitotic spindle that will eventually pull the chromatids apart develops during the S phase.

Preparing for Action

Most of the final phase of meiotic interphase is much like the G1 phase and is known simply as the G2 phase. The cell continues to grow and perform its cellular duties with the double chromosomes tucked inside a nuclear membrane. At the final moments of the G2 phase in animal cells, bundles of microtubules called centriole pairs duplicate within the centrosome and become well-defined. These two centriole pairs will later produce the spindle of fibers that will pull the chromatids apart. During the other phases of interphase, the centrosome has only one centriole pair and appears as a poorly defined dark spot near the nucleus.

Completing the Division

Unlike mitosis where only one division occurs, cells undergoing meiosis experience two cell divisions. The first division is similar to mitosis and results in two daughter cells with the same number of chromosomes as the mother cell. These two daughter cells then experience a second division to make four cells. Because there is no interphase between the two divisions, the chromosomes within the two daughter cells do not have time to double again before this second split. The second division halves the chromosome number in the two daughter cells, producing four cells with only half the number of chromosomes as the original mother cell.