The metric system is a modern alternative system of measurement used worldwide, including in the United States (US). It is commonly used in laboratories.
The metric system uses a series of prefixes, including deci-, centi-, milli-, micro-, and others, and joins them with one of the 3 base units of measurement: meter (length), liter (volume), or gram (mass or weight). These prefixes indicate larger or smaller measures of the base unit.
The base units most frequently used in the histology laboratory are the liter and the gram. Tables 1 and 2 show commonly used prefixes (with their symbols and equivalents) in the histology laboratory.
Table 1. Base unit = liter.| Prefix + Base Unit | Symbol | Value | Power of 10 |
| Deciliter | dL | 0.1 L | 10-1 |
| Centiliter | cL | 0.01 L | 10-2 |
| Milliliter | mL | 0.001 L | 10-3 |
| Microliter | µL or mcL | 0.000001 L | 10-6 |
Table 2. Base unit = gram.| Prefix + Base Unit | Symbol | Value | Power of 10 |
| Decigram | dg | 0.1 g | 10-1 |
| Centigram | cg | 0.01 g | 10-2 |
| Milligram | mg | 0.001 g | 10-3 |
| Microgram | μg or mcg
| 0.000001 g | 10-6 |
