Transverse cross-section at thoracic level T9. Tape-mounted histology stained according to a modified Mallory-Cason protocol. A = anterior; DRG = dorsal root ganglion; iimb = internal intercostal membrane; in = intercostal nerve; L= lateral; M=medial; P=posterior; pp = parietal pleura; r = rib; SCTL = superior costotransverse ligament (dotted outline); ST = sympathetic trunk; vp = visceral pleura.