Cultured cells can be encouraged to assemble primary cilia by removing serum from their growing medium to induce exit from the cell cycle. Madin Darby Canine Kidney (MDCK) and Inner Medullary Collecting Duct 3 (IMCD3) are commonly used renal epithelial cells lines that assemble primary cilia and have proved invaluable for investigating components involved in cilium-based signalling pathways. Techniques have also been developed to study the primary cilia produced by cultured metanephric mesenchyme. Similarly, cultured mouse embryonic fibroblasts derived from knockout and transgenic strains are widely used to this website study the genetic basis of primary cilium function. As a general rule, immunolocalization of ciliary components is easier in cultured cells than kidney sections. Most of the reagents used for electron microscopy are hazardous and provision needs to be made for their safe handling and disposal. A fume cupboard and appropriate protection are essential. For best preservation mouse kidneys are perfusion fixed. The mouse is deeply anaesthetized with ketamine anaesthetic and perfused via the left ventricle
of the heart with nicking of the inferior ABT-263 research buy vena cava to allow blood and perfusate to escape. Perfusion takes place on an absorbent pad, or on a tray with a hole draining to a beaker in the fume hood sink. This allows escaping perfusate to be collected so that it can be disposed of appropriately. see more Perfusion should not exceed normal mouse blood pressure (100–130 mmHg) to avoid damaging the kidney. Gravity fed perfusion systems are frequently used and will give a pressure equivalent to approximately 75 mmHg if perfusion fluid is at an elevation of 1 m above the animal. Some custom made and commercial perfusion apparatus (e.g. Leica Perfusion One) use
a chamber with controlled air pressure to regulate perfusion pressure. Perfusion begins with phosphate buffered saline (PBS) at 37°C until blood is flushed and is followed by fixative composed of 2.5% glutaraldehdye and 2% formaldehyde in phosphate buffer or cacodylate buffer. Phosphate buffer is the easier non-toxic option; however, toxic cacodylate buffer may offer better preservation and less chance of precipitate forming in the specimen. The kidneys are removed and cut into several smaller pieces, immersed in fixative for 2–5 h, washed three times in buffer, post-fixed in 1% osmium tetroxide in buffer for 1 h, washed in buffer then three changes of water. A perfusion fixation approach is also applicable to rat kidneys. Kidneys from embryonic mice are dissected out at the desired developmental stage and can be immersion fixed intact because of their small size. Human kidney samples are cut into small pieces and immersion fixed using the same sequence of fixatives.