Distribution of cells containing FMRFamide‐related molecules in the embryonic development of Ophryotrocha labronica (Polychaeta: Dorvilleidae)

Abstract

Abstract. The timing and spatial distribution of cells containing FMRFamide‐related molecules in the embryogenesis of the polychaete Ophryotrocha labronica were studied immunocytochemically. FMRFamide‐like molecules emerge early during embryonic development. They are found at the one‐cell stage, are asymmetrically distributed in the first phases of cleavage, associated with gastrular movements, and label the central nervous system morphogenesis. Moreover, during embryogenesis, the pattern of gut cells with the FMRFamide‐like phenotype that is present in adults is already established. The early occurrence of FMRFamide‐like molecules in O. labronica suggests that these molecules are involved as pre‐nervous growth signals in the regulation of basic neuronal cell behaviors.

Some aspects of spiralian development

“…Observations on asymmetric distribution of yolk granules and various molecules in the unfertilized egg, such as FMRFamide-related molecules in the eggs of the polychaete Ophryotrocha (Franchini 2008), indicate a considerable spatial organization already before fertilization. In the gastropod Lymnaea, (Raven 1963) observed six special subcortical patches around the periphery of the egg immediately after oviposition, apparently corresponding to the six follicle cells which typically surround the developing oocyte.…”

RFamide Peptides in Early Vertebrate Development

“…Interestingly, FMRFa are expressed in the nervous system at very early developmental stages in several phyla of metazoans, as mollusks (cephalopods and gastropods) ( 9 , 10 ), cnidarians ( 11 ), and annelids (a polychete) ( 12 ). This may indicate an evolutionary ancient role of FMRFa in the development of the nervous system.…”