Attention deficit hyperactivity disorder (ADHD) should be diagnosed and treated in children as young as age 4, according to new guidelines from the American Academy of Pediatrics. Skip to main content
ephemeris. 1  a table showing the positions of a heavenly body on a number of dates in a regular sequence. 2  an astronomical almanac containing such tables. 3  Archaic. an almanac or calendar.
For the fungal structure of the same name, see Pileipellis. Epithelial (epi- + thele + -ium) is one of the four basic types of animal tissue, along with connective tissue, muscle tissue and nervous tissue. Epithelial tissues line the cavities and surfaces of blood vessels and organs throughout the body.