Endomitosis/Endoreduplication Definition
Endomitosis or endoreduplication is DNA synthesis within a cell without accompanying cell or nuclear division.
Understanding Endomitosis/Endoreduplication
Endomitosis (also called endoreduplication) is a specialized cellular process that involves:
- Replication of DNA within the cell nucleus
- Absence of subsequent cell division or nuclear division
- Results in increased DNA content within a single cell
- Creates polyploid cells with multiple copies of the genome
This process differs fundamentally from the other options presented:
- It is NOT the exchange of chromosomal portions forming translocations (option B)
- It is NOT secretion of cell granule contents (option C)
- It is NOT a type of cell division that reduces chromosome number (option D)
Molecular Mechanism
The molecular basis of endoreduplication involves:
- Inhibition of M phase-promoting factor (MPF) activity 1
- Induction of S phase-related protein kinases 1
- DNA replication cycles that occur without mitosis
- Oscillations in S-phase cyclin-dependent kinase activity 2
Biological Significance
Endoreduplication serves several important biological functions:
- Increases gene expression levels in metabolically active tissues 2
- Associated with terminal differentiation of cells 2
- Linked to increased cell size in various organisms 3
- Common in plants and animals, especially in tissues requiring high metabolic activity 2
Examples in Biology
Endoreduplication occurs in various biological contexts:
- Plant tissues: endosperm, cotyledons, trichomes, and leaf epidermis 4
- Human tissues: trophoblast cells of the placenta 5
- Drosophila salivary gland nuclei 5
- Arabidopsis: essential for proper growth of specific cell types 3
Clinical Relevance
Understanding endoreduplication has implications for:
- Developmental biology - critical for normal development in many organisms
- Cell growth regulation - linked to cell size determination
- Specialized tissue function - enables high metabolic activity in specific tissues
The process of endoreduplication is distinct from mitotic catastrophe, which involves failed mitosis leading to cell death, and from other cell death modalities such as anoikis, entosis, and parthanatos 6.