c("age: 12 weeks gestation", "developmental stage: fetus", "tissue: heart")
c("age: 12 weeks gestation", "developmental stage: fetus", "tissue: brain")
c("age: 12 weeks gestation", "developmental stage: fetus", "tissue: brain")
c("age: 12 weeks gestation", "developmental stage: fetus", "tissue: heart")
c("age: 12 weeks gestation", "developmental stage: fetus", "tissue: liver")
c("age: 12 weeks gestation", "developmental stage: fetus", "tissue: liver")