title: A phase-contrast device with positive and negative image contrast.
mesh_terms: D000818:Animals; D001773:Blood Cells; D002415:Cats; D004847:Epithelial Cells; D006801:Humans; D008046:Lip; D008722:Methods; D008858:Microscopy, Phase-Contrast / Q000295:instrumentation; D012469:Salivary Glands / Q000033:anatomy & histology