Histological sections of P. heisei. (A) labral region; (B–C) middle frontal region; (D) posterior frontal region (see inserted figure with dotted lines indicating position and orientation of sections). Abbreviations: br, brain; ce, compound eye; fp, frontal pouch; lhg, labiohypopharyngeal gland; lr, labrum; lrg, labral gland; mg, mandibular gland; mp, maxillary palp; oes, oesophagus; pph, prepharynx; t, tentorium.