| PI | first meiotic prophase; isoelectric point; pacing impulse; package insert; pancreatic insufficiency;... |
|---|---|
| S1-S5 | first to fifth sacral nerves |
| S1-S4 | first to fourth heart sounds |
| T1-T12 | first to twelfth thoracic vertebrae |
| T1 | spin-lattice or longitudinal relaxation time; tricuspid first sound |