No abstract

Eggs of Trichuris muris hatched in the cecal contents of mice. A new method was used to calculate the volume changes in the eggs and larvae during hatching under simulated in vivo conditions. Previously quiescent larvae were activated and performed a series of purposeful movements within the egg that resulted in the head and stylet penetrating one of the polar plugs. In the final stage prior to emergence from the egg, there was significant swelling of the eggs due to endosmosis, which was critical for successful hatching. The hatched larvae were also significantly bigger than the resting larvae. Some observations on egg morphology are made, and a mechanism for hatching of T. muris is described.

A growth curve for Trichuris muris on the basis of total body length is presented, together with more detailed observations than previously described on the moulting pattern in this nematode developing in DBA-2 mice. The first moult was on days 9–11 after infection of mice with the nematode, at which time sex of the worms was generally not recognisable. The second moult was on days 20-21, when sex of the majority of the worms was recognisable. The third moult was on day 25 (males) and days 28–30 (females). The fourth moult was on day 28 (males) and days 32–34 (females). In general, the various moults were found to be much less "synchronous" than has been previously reported, with the exception of the third and the fourth moults in males. The active role of the stylet during emergence of the nematode from the moulted cuticle was evident.

The survival of two Canadian isolates of the pinewood nematode, Bursaphelenchus xylophilus, in coniferous wood chips under different temperatures, relative humidities and time intervals was investigated in vitro. The nature of the survival mechanism was examined and it was shown that the nematode's prolonged survival in the chips depended on its dispersal third larval stage. The possibility of PWN‐infested wood chips spreading PWN‐induced pine‐wilt disease to forests is discussed.

Eggs of Trichuris muris hatched when implanted directly into the ceca of mice. The hatched larvae had penetrated the epithelium 40 min after introduction of the eggs. It is certain that the larvae penetrated the epithelium lining the cecal glands after entering the glands. Since penetration through the surface or luminal epithelium was not observed, it may be that the larvae enter gland openings selectively before penetrating epithelial cells.