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

Abstract

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. In 27-dpf larvae, the ultrastructural analysis shows the presence of the interrenal cells with mitochondria with tubulovesicular cristae, typical of steroidogenic cells, sometimes surrounded by smooth endoplasmic reticulum (SER) cisternae, indicating that in this stage the cells have the capacity for steroid synthesis and secretion. In the same stage the chromaffin cells are characterized by few and small membrane-bound granules containing cores of heterogeneous electron density. Both types of cells show large nuclei, numerous free or clumped ribosomes, developed rough endoplasmic reticulum (RER), and scarce SER. Rare nerve endings contacting chromaffin cells are present. In the subsequent developmental stages, a further differentiation of both types of cells is evidenced by modifications of cell organelles as mitochondria, chromaffin granules, RER, SER, and so on. A clear discrimination of the two types of catecholamine-containing cells, adrenaline and noradrenaline cells, is evident only 5 days after hatching. The presence of different interrenal cell types in larvae at 5 and 10 days after hatching probably indicates the activation of a physiological cellular cycle. The immunohistochemical and ultrastructural results are compared with those obtained by other authors in the same and other vertebrate species.

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

“…The two types of granules were first mingled in the same cell and their separation into different cells occurred only at the end of the advanced period. Other authors reported similar characteristics in different species of reptiles (Doddamani 2000;Rupik 2002), amphibians (Accordi et al 1975;Accordi and Grassi Milano 1977) and fish (Gallo and Civinini 2005). The chromaffin cells had only scarce innervation at the beginning of development; nerve endings were frequently observed only at the end of it.…”

“…In particular, their polymorphic shape and their long cytoplasmic projections could be related to their migrating fitness, by amoeboid movements. Similar characteristics have also been described in the adrenal of the rainbow trout Oncorhynchus mykiss (Gallo and Civinini 2005), the toad Bufo bufo (Accordi and Grassi Milano 1977) and the grass snake Natrix natrix (Rupik 2002).…”

Morphological and histological study of larval development of the Senegal sole Solea senegalensis: an integrative study

“…A limited number of studies on the development of interrenal tissue during fish larval development can be found in the literature (Tanaka et al , 1995; Gallo & Civinini, 2005). In the case of S. senegalensis , the development of interrenal tissue at stage 4 may indicate a major change in the corticosteroidogenic activity at pre‐metamorphosis in parallel to the early development of the hypophysis.…”

“…Chromaffin cells could not be identified in this study, thus the potential production of catecholamines and their role in stress response cannot be discussed here. In rainbow trout Oncorhynchus mykiss (Walbaum 1792), chromaffin cells have been first observed later in development than the interrenal cells and lower in numbers (Gallo & Civinini, 2005).…”

The ontogeny of regulatory control of the rainbow trout (Oncorhynchus mykiss) heart and how this is influenced by chronic hypoxia exposure

“…Indeed, higher adrenaline levels after hatching relative to previous stages were found in the head and heart tissues of rainbow trout larvae (Meyer and Sauerbier, 1977). In addition, nervous control of catecholamine secretion from chromaffin cells of trout was reported as early as pre-hatching stage 28 (Gallo and Civinini, 2005). Therefore, the higher adrenergic tone on heart rate can presumably be related to increasing levels of circulating catecholamines.…”