These are fixed, permeabilized, and fluorescently-stained muntjac skin fibroblasts in either interphase or a phase of mitosis. The phases, going from top left to bottom right, are: interphase, prophase, metaphase, anaphase, and telophase.
During interphase, a eukaryotic cell multiplies its inventory of organelles and replicates its DNA (pink), growing in size.1 Next, mitosis is activated and the cell enters prophase, during which its replicated DNA is supercoiled into chromosomes comprised of identical, paired sister chromatids. Eventually, the cell’s nuclear envelope disintegrates, and special microtubules (green) linking the kinetochores of chromatids to the cell’s poles develop. The cell then enters metaphase, during which the centromeres of its chromosomes become aligned in a plane at its equator. After passing a key mitotic checkpoint, the cell enters anaphase, during which the paired sister chromatids separate and are pulled to opposite poles. Finally, in telophase, nuclear envelopes and nucleoli re-form around each pole’s collection of DNA, chromatids uncoil back into chromatin, and the cell divides in two. Each daughter cell is at the start of interphase, and the cell cycle repeats.2
Alexa Fluor® 350 phalloidin labeled actin filaments (blue) throughout each cell. An anti-α-tubulin antibody prelabeled with the Zenon® Alexa Fluor® 488 Mouse IgG1 Labeling Kit marked microtubules (green), revealing their role in mitosis. The anti–Cdc6 peptide antibody prelabeled with the Zenon® Alexa Fluor® 647 Mouse IgG1 Labeling Kit stained DNA (pink) in both chromatin and chromosomes.
References: (1) Clare O’Connor, Nature; (2) D. Sadava et al., Nature.
Photos: courtesy of the Life Technologies Corporation.