Stains which make the nucleus distinct

What kinds of histological stains are there? Most cells are colourless and transparent, and therefore histological sections have to be stained in some way to make the cells visible. The techniques used can either be non-specific, staining most of the cells in much the same way, or specific, selectively staining particular chemical groupings or molecules within cells or tissues. Staining usually works by using a dye, that stains some of the cells components a bright colour, together with a counterstain that stains the rest of the cell a different colour. Basophilic and acidophilic staining. Acidic dyes react with cationic or basic components in cells. Proteins and other components in the cytoplasm are basic, and will bind to acidic dyes. Another way of saying this is that cytoplasmic proteins are acidophilic (acid liking - i.e. bind to acidic dyes). Basic dyes react with anionic or acidic components in cells. Nucleic acids are acidic, and therefore bind to basic dyes. Another way of saying this is that nucleic acids are basophilic (basic liking). H&E staining The most commonly used staining system is called H&E (Haemotoxylin and Eosin). H&E contains the two dyes haemotoxylin and eosin. Eosin is an acidic dye: it is negatively charged (general formula for acidic dyes is: Na +dye -) . It stains basic (or Thus the cytoplasm is stained pink in the picture below, by H&E staining. Haematoxylin can be considered as a basic dye (general formula for basic dyes is:dye + Cl -). Haemot...

This article covers • • • • • • • • • • • • • • • • • • • Why do we need biological stains for microscope? Many biological specimens are near transparent and have very little contrast between the object and the surroundings. These kinds of specimens are difficult to see under a regular microscope. Staining is the most common technique to enhance the visibility of your specimens by increasing the contrast. Stains or dyes can bind to certain types of components of the specimen by their chemical nature, resulting in highlighting these biological structures to stand out of the background. [In this figure] An example of using stains to visualize transparent specimens. You can easily peel off a piece of What can biological stains do? Biological staining is an art of science. There are thousands of chemical stains and dyes that have been studied by the scientists to label specific components, for example, organelles (like nucleus and mitochondria), biological molecules (like sugar, lipid, protein, or DNA), and microorganisms (like Gram stains for bacteria). More advanced techniques like antibody-based immunofluorescent staining (IF) and nucleotide-based fluorescence in situ hybridization (FISH) can go even deeper and distinguish one specific protein from thousands of other proteins (IF) or one unique DNA code from an unlimited combination of possibility (FISH). [In this figure] Various staining techniques are powerful tools for biological and medical research. (A) A cross-section...

The nucleus of the cell is a membrane-bound organelle that includes the nuclear envelope, nucleolus, and nuclear matrix, and is the site of gene expression. The nucleus can be selectively visualized by staining nuclear proteins or directly staining nucleic acids. Here we describe a wide selection of nuclear stains that are available with a choice of wavelengths for multiplexing and colocalization in either live or fixed cells. Cell-permeant nucleic acid stains make it possible to stain live cells or tissues with minimal processing. They reveal the natural location of cells in tissues and provide a means to follow nuclear changes throughout cellular processes, from mitosis to apoptosis. Cell-impermeant nucleic acid stains, used with fixed cells or tissues, are also used as dead-cell indicators providing a means to follow cellular processes, from apoptosis to viability. See nucleus stains selection guide The nucleus (plural: nuclei) is found in eukaryotic cells. While most cells have a single nucleus, some cell types do not have a nucleus while others have many nuclei. A cell’s nucleus is a membrane-bound organelle that consists of the nuclear envelope, a double membrane that surrounds and isolates the nuclear contents, and the nuclear matrix which acts like the cytoskeleton and provides support [ 1,2]. The nucleus contains the cell’s genetic material (chromosomes) and is the primary site of gene expression and DNA replication during cell cycle. The nucleus also contains...

When cells are not dividing, you cannot see the chromosomes, and the nucleus looks like this photograph of a cell seen under the microscope where you can see the nuclear membrane surrounding a salmon pink area. At this stage, the chromosomes are not visible – just this mass of nuclear material called chromatin. This is where DNA (deoxyribose nucleic acid) is found. Scientists who study the nucleus and how cells divide are called cytogeneticists. Just before cells start to divide, the chromosomes become visible. Cytogeneticists stain the dividing nucleus and look at them under high-powered microscopes to examine these visible chromosomes. They line them up and sort these chromosomes into different types. All the chromosomes in a human cell is called a karyotpe. Chromosomes can be identified by size and shape. There are 22 pairs of chromosomes that carry most of the genetic messages in the human cell. The 23 rd pair of chromosomes are called the sex chromosomes. Because of their shape they are called X chromosomes or Y chromosomes. Females have two X chromosomes (XX) and males have one X and one Y chromosome (XY). Here is an arrangement of chromosomes from a human female. Can you see the two X chromosomes? How many chromosomes can you count? There should be 46 or 23 pairs. When chromosomes are visible, they look like this. Each chromosome is made up of two identical strands called chromatids (1). Where they join is called the centromere (2). Along these chromatids are arrang...

Next Section INTRODUCTION For the study of microscopic anatomy and of pathological material, it is usual to stain sections of tissue in such a way as to impart a dark color to the nuclei of cells and a lighter, contrasting color to the cytoplasm and extracellular structures. Nuclear stains, including cationic, anionic, and metal complexing dyes, are considered in this article. The rationales of the techniques are discussed, but methods of higher chemical specificity (e.g., for nucleic acids, carbohydrates, and functional groups of proteins) are not covered. Previous Section Next Section NUCLEAR STAINS The nucleus of a eukaryotic cell contains the two nucleic acids: DNA in the chromosomes, and RNA in the nucleolus. Both are associated with strongly basic nucleoproteins: These are histones in diploid cells or protamines in haploid cells such as spermatozoa. Nucleoproteins are rich in the amino acids arginine and lysine. The cations of these amino acids are neutralized by phosphoric acid residues of the nucleic acids. The DNA and nucleoprotein of the chromosomes together constitute the material known as chromatin, named for its prominence in most stained preparations. In interphase cells, the chromosomes are extended and cannot be seen individually. The chromatin seen in stained preparations of interphase nuclei may be evenly distributed through the nucleoplasm or aggregated in a pattern characteristic of the cell type. The dyes used as nuclear stains impart color to the chro...

\( \newcommand\) • • • • • • • Interphase Cells spend most of their time in a stage called interphase. During this phase, the nuclear envelope surrounds the nucleus. There may be one or more nucleoli (dark, condensed regions) visible within the nucleus. The material around the nucleoli, contained within the nuclear envelope is DNA in the form of chromatin. This will not pick up a stain well and so will not appear as distinct shapes within the nucleus. Find these indicators of interphase in cell A in the image below. Figure \(\PageIndex\): Cells in an onion root in interphase and prophase. Cell A has a large, dark nucleolus surrounded by greyish material (chromatin) that is enclosed within the nuclear membrane. A cell wall makes a box around each cell and the plasma membrane would be located just inside this box, though we cannot easily see it. In cell B, the chromatin is condensing and begins to look like dark, thick strands. It is still contained in the center of the cell, as the nuclear envelope has not finished dissolving. Photo by Maria Morrow, In contrast, when a cell begins the process of division, the chromatin condenses into visible chromosomes that will pick up a stain and look like dark strings within the nuclear envelope, as seen in cell B in the image above. In order to begin dividing, the cell needs to go through several processes that take place during interphase, including replicating the DNA (occurs in S-phase) and all of the cell contents. Mitosis Mitosis...