Retrocerebral endocrine complex and postcerebral portion of stomatogastric nervous system in lower Brachycera-Orthorrhapha. 3. Xylomyidae, Coenomyiidae, and Xylophagidae.

摘要

The structure of the retrocerebral endocrine complex (REC) and stomatogastric nervous system (SNS) differ significantly in members of the dipteran families studied. In Xylomya, the nervi corporis cardiaci (NCC) do not fuse with the aorta wall and run independently up to their entrance into posterior portions of the corpora cardiaca (CC). The CC consist of an anterior unpaired part, formed by intrinsic secretory cell processes, and posterior paired parts composed of secretory cell bodies. The CC posterior parts are in close contact with an unpaired corpus allatum (CA). There are distinct hypocerebral and ventricular ganglia. The oesophageal nerve is partly fused with the unpaired CC portion, providing the fibre exchange between REC and SNS. In Coenomyia, the NCC are fused with the aorta wall, the CC are paired and connected with the CA via the nervi corporis allati. The hypocerebral and ventricular ganglia are well developed and not connected with the aorta wall. In Xylophagus, the NCC are also fused with the aorta wall, and the CC include an unpaired anterior portion composed of intrinsic secretory cell processes and paired posterior ones formed by secretory cell bodies. There is a pair of the nerir corporis allati. The cerebral neurosecretory materials are stored in the aorta wall and in the CC. The hypocerebral ganglion is indistinct, but the ventricular ganglion is well developed. There are anastomoses between CC and the oesophageal nerve. The complete structure of the organs studied does not appear to reflect taxonomic interrelations between families. In the lower Brachycera-Orthorrhapha, the REC and SNS of Rhagionidae and Stratiomyidae have the most common characters, whereas those of Tabanidae are specific.