Morphology in ultrastructure

Sometimes Neotropical land snails are used for fundamental research. Moraes et al. (2010) investigated the ultrastructure of snail brains in Megalobulimus abbreviatus (Bequaert, 1948), viz. the dorsal body; this is an endocrine gland located above the cerebral ganglia in all pulmonate molluscs.


The abstract of this paper shows that this species was strictly used in an endocrinological context. 

The ultrastructure of the reproductive gland, dorsal body (DB), of Megalobulimus abbreviatus was analysed. Electron microscope immunohistochemistry was used to detect FMRFamide-like peptides in the nerve endings within this gland. Nerve backfilling was used in an attempt to identify the neurons involved in this innervation. In M. abbreviatus, the DB has a uniform appearance throughout their supraesophageal and subesophageal portions. Dorsal body cells have several features in common with steroid-secreting gland cells, such as the presence of many lipid droplets, nu- merous mitochondria with tubular cristae and a developed smooth endoplasmic reticulum cisternae. Throughout the DB in M. abbreviatus numerous axonal endings were seen to be in contact with the DB cells exhibiting a synaptic- like structure. The axon terminals contained numerous electron-dense and scanty electron-lucid vesicles. In addition, the DB nerve endings exhibited FMRFamide immunoreactive vesicles. Injection of neural tracer into the DB yielded retrograde labelling of neurons in the metacerebrum lobe of the cerebral ganglia and in the parietal ganglia of the subesophageal ganglia complex. The possibility that some of these retrograde-labelled neurons might be FMRFamide- like neurons that may represent a neural control to the DB in M. abbreviatus is discussed.

However, what is interesting to note, is that this species was “previously cited incorrectly as Megalobulimus oblongus or Strophocheilus oblongus” (Moraes et al, 2010: 342). Quite confusing… Especially when such studies are used for comparative morphology (perhaps at a later stage). It may thus be important that biologists from a distinct discipline have a taxonomist involved, to check the correct taxonomic status of their object of study. It is to be regretted that the authors didn’t state to which studies they are referring to clear the potential confusion when this paper is later used in e.g. a review.

Moraes, G.D., Achaval, M., Dal Piva, M.M., Faccioni-Heuser, M.C., Wassermann, G.F. & Zancan, D.M., 2010. Ultrastructural analysis of the dorsal body gland of the terrestrial snail Megalobulimus abbreviatus (Bequaert, 1948) – Brazilian Journal of Biology 70: 341-350.

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