-210- 



One type, for which he resurrected the term "nectomonad" 

 corresponds in size and shape to the long-slender, highly motile forms 

 observed in the midguts of L mejdcana- infected _Lu. diabol ica and Lu . 

 shannoni two to three days postinfective feed. The second type 

 appeared as the promastigotes migrated forward to colonize the 

 thoracic midgut (cardia). This type corresponds to the short- 

 broad, dividing forms seen after three days, packed behind and 

 attached to the stomodeal valve. For these, Ki 1 1 ick-Kendrick (1979) 

 revived the name "haptomonad." According to him, the change from 

 nectomonad to haptomonad is a modification associated with 

 establishment of infection in a different part of the gut, and 

 represents a change in habitat. It appears to be associated with the 

 indispensable step of forming hemidesmosomes which attach to the 

 cuticular parts of the stomodeal valve (Fig. 4-15). 



The significance of the nondividing, binucleated promastigote and 

 the extremely long promastigote (Fig. 4-9 and 4-10) observed in a 

 five-day infection of L mexicana in Lu_. diabol ica remains obscure. 

 Molyneux (1983) reported that "giant multinucleate forms" and other 

 bizarre forms have been observed in other trypanosomatids ( Trypanosoma 

 brucei and T. rangel i ) and suggested that they could possibly have 

 something to do with genetic exchange in these parasites. 



Ki 1 1 ick-Kendrick (1979) observed that L. m. amazonensis divides in 

 the abdominal midgut of Lu. longipalpis but never in the cardia. In 

 this respect, L mexicana (strain WR-411) in L_u. diabol ica behaved 

 differently, since division occurred in forms in the abdominal midgut, 

 cardia, and attached to the stomodeal valve. Lainson et al. (1977) 



