[1] HAMMERSMITH HOSP, DEPT HISTOCHEM, LONDON W12 0HS, ENGLAND
[2] LONDON HOSP, DEPT GASTROENTEROL, LONDON E1 1BB, ENGLAND
[3] LONDON HOSP, DEPT HISTOL, LONDON E1 1BB, ENGLAND
[4] ST BARTHOLOMEWS HOSP, DEPT HISTOPATHOL, LONDON EC1A 7BE, ENGLAND
[5] UNIV CATTOLICA SACRO CUORE, DEPT ANAT, I-00168 ROME, ITALY
[6] NIMH, DEPT CLIN PSYCHOBIOL, BETHESDA, MD 20205 USA