DR. ALBERTINI’S PHOTO GALLERY
BRIEFING: Our photo gallery this time has the theme, cells dividing every which way! It features possibly one of the most remarkable processes in all of biology and medicine, - cell division! While the static images gathered here may tell a story about the working machinery at play when both our genomes (chromosomes) and cytoplasm become perfectly separated into two “equivalent” daughter cells, watching this process in action is something we encourage our readership to enjoy on the internet. The star of this “show” is the spindle- a complex amalgam of cytoskeletal components known as microtubules and actin filaments that under the orchestration of many regulatory molecules see to it that in most cases cell division proceeds according to plan. That this may not always happen can be for better or worse for the products of mitosis or meiosis!
FIGURE 1
Demonstrates h14. The infamous HeLa cells shown here sometimes get it “right” and sometimes not. Three dividing cells occupy the center of this image representing steps in the mitotic process that coordinate chromosome positioning (blue) with microtubules in the spindle (red) and special organizers known as centrosomes (in yellow).
FIGURE 2
demonstrates tripole. Too many cooks (centrosomes) sometimes spoil the recipe leading to spindles in this case with three poles, a situation that nearly always will result in an abnormal number of chromosomes in “daughter” cells.
FIGURE 3
Demonstrates Recon. Moving here along from mitosis to meiosis, we capture the meiotic spindle of a human oocyte making a last-ditch effort to corral all of its chromosomes in the midzone of the spindle, - so it can get on with the business at hand, to separate bivalents and emitting a first polar body that would genetically position the oocyte in a state of preparedness for fertilization
FIGURE 4
Shows kh1d. Once fertilization has occurred, the one cell embryo or zygote will proceed through now a series of mitotic divisions as shown here in a 4-cell embryo in which two of the blastomeres are preparing for the big event! Note the ordered alignment of the chromosomes (blue) on the spindle (green) in the upper blastomere compared to the apparent state of disarray in the lower cell. Errors in mitosis during early embryonic cell divisions are the principal cause of aneuploidy in human embryos.