Morphology of developing Trichosomoides nasalis in Arvicanthis niloticus.

A. First-stage larva, three days old, showing nerve ring, muscular oesophagus, long stichosome and short intestine, left lateral view. B-D. Female larva 2,800 μm long at very beginning of fourth moult; B. Oesophageal-intestinal junction and vulva (under exuvial sheath), vagina and distal part of uterus, right lateral view; C. Continuation of B, with uterus and intestine; D. Posterior extremity with rectum, lateral view. E-G. Female larva, 2,350 μm long; E. Head and stylet; F. Posterior region with ovary, intestine and rectum, and slight terminal exuvial sheath, dorso-ventral view; G. Bacillary band at posterior extremity, lateral view. H. Adult male 1,750 μm long, oesophageal-intestinal junction 1,050 μm from head. I. Same male, posterior extremity with intestine (on left), ejaculatory duct and cloaca, lateral view. J. Bacillary band at posterior extremity of a male, lateral view. K-L. Adult female 5,000 μm long with male; K. Male anterior part, its head oriented to vulva (note the stichocytes dark or clear); L. Male posterior part in uterus.

A-G: worms from abdominal wall, H-L: worms from nasal mucosa. All worms recovered from series of re-infected rodents, except the first-stage larva.

Scale bars in μm: A, K, L, 50; B, C, 40; D-J, 20.