Catecholaminergic System of Invertebrates: Comparative and Evolutionary Aspects in Comparison With the Octopaminergic System.

In this review we examined the catecholaminergic system of invertebrates, starting from protists and getting to chordates. Different techniques used by numerous researchers revealed, in most examined phyla, the presence of catecholamines dopamine, noradrenaline, and adrenaline or of the enzymes involved in their synthesis. The catecholamines are generally linked to the nervous system and they can act as neurotransmitters, neuromodulators, and hormones; moreover they play a very important role as regards the response to a large number of stress situations.

Cell secretion mediated by granule-associated vesicle transport: a glimpse at evolution.

Regulated secretion allows extrusion of cell products stored in specialized membrane-bound organelles called secretory granules or secretory vesicles. Regulated secretion provides basic functions in living organisms, and in a phylogenetic perspective, it is recognizable in the most primitive eukaryotic forms. This article is an attempt to trace the evolutionary history of a special type of secretory pattern, which has been referred to as vesicle-mediated degranulation or piecemeal degranulation (PMD).

Degeneration and possible renewal processes related to the interrenal cells in the head kidney of the stickleback Gasterosteus aculeatus.

The ultrastructural aspect of degeneration and recovery processes involving the steroidogenic interrenal cells of the stickleback was studied. Together with the adrenergic cells, the interrenals constitute the adrenal homolog in teleosts. From our study it appears that a process of massive cell death may lead to temporary disappearance of the gland.

Chromaffin cells in the adrenal homolog of Aphanius fasciatus (teleost fish) express piecemeal degranulation in response to osmotic stress: a hint for a conservative evolutionary process.

The effect of severe osmotic stress on the ultrastructural morphology of chromaffin cells in the adrenal homolog of Aphanius fasciatus, a small eurhyaline teleost living in saltpans, was evaluated by electron microscopy quantitative analysis. Fishes were transferred from salt water, whose salinity was 3.7%, to dechlorinated tap water and chromaffin cells were studied at resting condition and after 2 and 48 hr from the beginning of the experiment.

Differentiation of chromaffin cells in the developing adrenal gland of Testudo hermanni.

The aim of this study was to investigate the development and differentiation of chromaffin cells in the adrenal gland of the turtle Testudo hermanni during ontogenesis using histological, immunocytochemical and ultrastructural methods. The 26 developmental stages were divided into three periods: in the early period (stages 1-18, up to 20 days of incubation at 37 degrees Celsius and 85% humidity), the chromaffin cells were observed from stage 12. They followed a ventro-lateral migration pathway with respect to the notochord and dorsal aorta, forming groups embedded in undifferentiated mesenchymal tissue.

The development of adrenal homolog of rainbow trout Oncorhynchus mykiss: an immunohistochemical and ultrastructural study.

In this work we describe the adrenal homolog of the rainbow trout Oncorhynchus mykiss during development. At the histological level, the interrenal primordium is clearly evident in larvae 25 days after fertilization (dpf), and the immunohistochemical reactions for tyrosine hydroxylase (TH) and phenylethanolamine-N-methyltransferase (PNMT), which mark the chromaffin cells, appear as early as 27 dpf. Both reactions are evident in cells localized in the head kidney and in some, probably migrating, cells close to the notochord.

Survey of the adrenal homolog in teleosts.

The adrenal homolog of teleosts is not a compact organ as the adrenal glands of most vertebrates but is composed by aminergic chromaffin and interrenal steroidogenic cells located mostly inside the head kidney that, in this taxon, generally has a hematopoietic function. The two tissues can be mixed, adjacent, or completely separated and line the endothelium of the venous vessels or are located in close proximity. The chromaffin cells in some species are also present in the posterior kidney.