Myringotomy and tympanostomy, in parallel with the general distinction between an -otomy (cutting) and an -ostomy (creating a stoma with some degree of permanence or semipermanence). In this distinction, only a tympanostomy involves tympanostomy tubes and creates a semipermanent stoma. This distinction in usage is not always made. The word "tympanocentesis" specifies that centesis (aspiration for sampling) is being done. Etymologically, "myringotomy" ("myringo-", from Latin "myringa" "eardrum", + "-tomy") and "tympanotomy" ("tympano-" + "-tomy") both mean "eardrum cutting", and "tympanostomy" ("tympano-" + "-stomy" means "making an eardrum stoma". In 1649, Jean Riolan the Younger accidentally pierced a patient's ear drum while
Development of the human body and temporal changes in gene expression, cell growth and cellular differentiation. A nearly identical process occurs in other species, especially among chordates. A fetus is a stage in the human development considered to begin nine weeks after fertilization. In biological terms, however, prenatal development is a continuum, with many defining feature distinguishing an embryo from a fetus. A fetus is also characterized by the presence of all the major body organs, though they will not yet be fully developed and functional and some not yet situated in their final location. The fetus and embryo develop within the uterus, an organ