@dr.bioforever: The great majority (>99%) of cells in our blood are red blood cells. But circulating in blood we also have white blood cells. These WBCs play very important roles in defending our bodies against pathogenic invaders such as bacteria. The majority (up to 70%) of WBCs in blood are neutrophils. . Neutrophils are the “first responders” of the immune system. When tissues are damaged or invaded by pathogens, distress chemical signals attract neutrophils to the affected area. When neutrophils detect the presence of bacteria, they attack them by eating them (phagocytosis), but they also die soon after (this is the way pus is formed). . The reason why I used methylene blue dye to detect WBCs is because methylene blue has affinity to stain DNA, so it stains cells by staining the cell nucleus. Unlike RBCs, which lose their nucleus after maturation, WBCs have a nucleus so they get easily stained with this dye. . In the last part of the video, you can see a comparison of the main 5 types of WBCs found in blood (platelets are also visible in this part of the video): 1) Neutrophils: these WBCs are the first responders to infections. They engulf and destroy bacteria and fungi through phagocytosis. 2) Lymphocytes: they coordinate specific (adaptive) immune responses after differentiating into B cells, T cells, or natural killer (NK) cells. B cells produce antibodies to target specific pathogens, T cells and NK cells play crucial roles in cell-mediated immunity. 3) Monocytes: they differentiate into macrophages and dendritic cells to engulf pathogens and present antigens to activate other immune cells. 4) Eosinophils: they attack parasites and play a key role in allergic reactions by releasing inflammatory mediators. 5) Basophils: they release histamine and other chemicals to mediate allergic and inflammatory responses. . Blood is such a fascinating and complex tissue! . For this video I used an Olympus CX31 microscope and an Olympus BX41 microscope at up to 1000× magnification. #microscopy #hematology #bloodcells #EduTok #LearnOnTikTokContest

Adolfo Sánchez-Blanco, Ph.D

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Saturday 27 June 2026 09:34:40 GMT