Cell Cycle Insights with Celloger® : From Theory to Live-Cell Imaging

Cells grow and divide through a tightly regulated process known as the cell cycle. This cycle plays a critical role in tissue development, maintenance, and regeneration, and is essential for repairing damaged structures in living organisms. A clear understanding of cell cycle progression and regulation is crucial for designing and analyzing experiments, and is fundamental in fields such as cancer research, tissue regeneration, and drug efficacy testing. In this article, we outline the key stages and regulatory mechanisms of the cell cycle. We also present observation examples that capture dynamic morphological changes in real time, specifically focusing on mitotic (M phase) progression in two different cell types using live-cell imaging. Table of Contents 1. Phases of the Cell Cycle 2. Cell Cycle Regulation 3. Observation Examples : Real-Time Monitoring of Cell Devision 1. Phases of the Cell Cycle The cell cycle consists of four main stages—G1 (Gap 1), S (Synthesis), G2 (Gap 2), and M (Mitosis)—with some cells entering an additional phase called G0. G1 Phase The cell grows and prepares the necessary proteins and energy for DNA synthesis. S Phase The cell duplicates its DNA so that each new cell receives an exact copy of genetic information. G2 Phase The cell checks for DNA damage and synthesizes additional components needed for mitosis. These three phases (G1, S, G2) are collectively referred to as interphase, during which the cell prepares for division. M Phase The duplicated chromosomes are separated, followed by cytokinesis, resulting in two daughter cells. The M phase consists of five substages — prophase, prometaphase, metaphase, anaphase, and telophase — and is the most dynamic and visually distinct phase, especially in live-cell imaging. G0 Phase Some cells exit the cycle into a quiescent state where they remain metabolically active but non-proliferative. This phase is typical of differentiated cells that no longer need to divide. 2. Cell Cycle Regulation Although the cell cycle progresses in a defined sequence, this progression is tightly regulated and not automatic. To ensure genomic stability and accurate division, cells utilize internal checkpoints that monitor readiness before transitioning to the next phase. When errors are detected, these checkpoints function as quality control systems, pausing the cycle to allow for repair. If regulation fails, uncontrolled proliferation may result — a key hallmark of cancer. Key checkpoints include: G1/S Checkpoint Assesses whether the cell is ready to enter the S phase. It verifies cell size, nutrient availability, and DNA integrity before allowing DNA replication. If this checkpoint fails, cells with damaged or incomplete DNA may continue dividing, increasing the risk of mutations and cancer development. G2/M Checkpoint Ensures that DNA replication is complete and error-free before the cell proceeds to mitosis. Failure at this point can lead to the transmission of genetic errors, contributing to genomic instability. Spindle Assembly Checkpoint During mitosis, confirms that chromosomes are properly attached to spindle fibers before segregation. Failure at this stage can cause chromosome missegregation and result in aneuploidy. These checkpoints serve as critical safeguards against abnormal cell proliferation. When damage cannot be repaired, the cell cycle halts and apoptosis(programmed cell death) is triggered. 3. Observation Example: Real-Time Monitoring of Cell Devision So far, we’ve reviewed the structure and regulation of the cell cycle. Now, let’s explore how cells behave in real time — focusing on their morphological changes during mitosis. Traditionally, cell morphology has been studied using fixed-cell imaging, which only captures static images and makes it difficult to track dynamic changes. With advancements in live-cell imaging, researchers can now continuously monitor the same cells over extended periods. The following examples demonstrate real-time observation of mitotic progression in two cases under different observation conditions using Celloger®. Observation Example 1 M phase of U-2OS cells This example presents mitotic progression of U-2OS cells, recorded using Celloger® Pro. U-2OS cells round up upon entering mitosis, with chromatin (green, GFP-H2B) condensing inside the nucleus. Further rounding and chromatin alignment are observed during prometaphase and metaphase. In anaphase, chromosome segregation becomes evident, followed by cleavage furrow formation during telophase. Observation Example 2 M phase of HeLa cell Mitotic progression of HeLa cells, captured with Celloger® Nano, exhibits similar morphological changes. These include cell rounding, chromatin condensation, chromosome segregation, and cleavage furrow formation. You can also explore how these cells behave over time in our full time-lapse video. 👉 Watch the full time-lapse video on our YouTube channel These images and video were captured using Celloger® Pro and Celloger® Nano during live-cell imaging. 👉 Learn more about Celloger® on our product page. In this article, we explored the phases and regulation of the cell cycle. In addition, we demonstrated how live-cell imaging with Celloger® captures the dynamic morphological changes of cells in real time. Live-cell imaging opens new perspectives in cellular dynamics research. Curiosis provides advanced imaging solutions like Celloger®, supporting researchers in their studies. Learn more about our technology and products on this website.

2025-10-02