"Medium" - what is it, definition of the term
A medium, in biological research, is a formulated solution or gel that delivers nutrients, growth factors, and a regulated environment to sustain and promote the proliferation of cells or microorganisms; it is engineered to meet the specific physiological requirements of organisms such as rats and mice, supplying amino acids, vitamins, salts, energy sources, and maintaining appropriate pH and osmolarity.
Detailed information
Cell culture substrates designed for rodent research provide essential nutrients, growth factors, and buffering capacity to sustain primary cells and established lines derived from rats and mice. Formulations typically contain a basal mixture of amino acids, vitamins, inorganic salts, and a carbohydrate source such as glucose. Supplementation with serum, usually fetal bovine, supplies hormones, attachment factors, and additional proteins that promote cell proliferation and viability.
Key components of a standard rodent cell substrate include:
- Amino acid blend – essential and non‑essential amino acids support protein synthesis.
- Vitamin cocktail – vitamins such as B12, biotin, and folic acid function as co‑enzymes.
- Inorganic salts – sodium, potassium, calcium, magnesium, and phosphate maintain osmotic balance and pH.
- Glucose – primary energy source for glycolytic activity.
- Buffer system – bicarbonate or HEPES stabilizes pH under atmospheric CO₂ conditions.
- Serum supplement – typically 10 % fetal bovine serum, providing growth‑promoting factors.
- Antibiotics (optional) – penicillin–streptomycin to reduce bacterial contamination.
For specific applications, researchers may select specialized substrates. Neural cell preparations from mouse brain often require neurobasal formulations enriched with B‑27 supplement, while fibroblast cultures from rat skin thrive in Dulbecco’s Modified Eagle Medium with high glucose concentration. Endothelial cells derived from rat aorta frequently use endothelial growth medium containing heparin and vascular endothelial growth factor.
When culturing organotypic slices, a semi‑solid substrate such as agarose or collagen gel supplies a three‑dimensional scaffold that mimics extracellular matrix properties. This environment preserves tissue architecture and enables long‑term electrophysiological recordings.
Quality control measures include sterility testing, mycoplasma screening, and verification of pH and osmolarity before use. Storage guidelines recommend refrigeration at 2–8 °C for liquid formulations and protection from light for vitamin‑sensitive components.
Overall, the selection of an appropriate nutrient solution for rat and mouse biological material depends on cell type, experimental objectives, and required duration of culture. Proper formulation and handling ensure reproducible results and reliable data generation.