“…The functional role of such structures is still unknown. However, these cells clusters closely resemble the strand of cells found until now exclusively in the genus Aplysina (Ereskovsky & Lavrov, 2021; Leys & Reiswig 1998), where these cells have a permanent position along the strands and do not actively move. According to Leys & Reiswig (1998, p. 40) the role of these cellsis primarily to bundle and align the collagen fibrils, creating a pathway that the cells transporting nutrients can recognize and follow, thereby allowing the rapid transport of material to the tip or to the base of the spongeandare suggestive of a primitive nutrient transport pathway in sponge.We follow these ideas and suggest that the cellular clusters of I. retidermata are part of the nutrient transport system towards sponge body districts.…”
Section: Discussionsupporting
confidence: 52%
“…In Ircinia retidermata , a dispersed fibrillar collagenic network is extended throughout the ectosomal/endosomal ECM, as in most demosponges (Ereskovsky & Lavrov, 2021 ; Simpson, 1984 ). These structures mediate cell‐matrix interactions via membrane receptors regulating cell behavior (Exposito et al, 2002 ; Müller, 1997 ) and contribute to build the architecture of the (a) chondrochyma‐like trabecular networks (Cowden & Harrison, 1976 ; sensu Minchin, 1900 ; Stocchino et al, 2021 ), and of (b) walls thickening of aquiferous canals and cavities.…”
In some Porifera (Demospongiae: Keratosa), prototypes of the connective system are almost exclusively based on collagenic networks. We studied the topographic distribution, spatial layout, microtraits, and/or morphogenesis of these collagenic structures in Ircinia retidermata (Dictyoceratida: Irciniidae). Analyses were carried out on a clonal strain from sustainable experimental mariculture by using light and scanning electron microscopy. Histology revealed new insights on the widely diversified and complex hierarchical assemblage of collagenic structures. Key evolutionary novelties in the organization of sponge connective system were found out. The aquiferous canals are shaped as corrugate‐like pipelines conferring plasticity to the water circulation system. Compact clusters of elongated cells are putatively involved in a nutrient transferring system. Knob‐ended filaments are characterized by a banding pattern and micro‐components. Ectosome and outer endosome districts are the active fibrogenetic areas, where exogenous material constitutes an axial condensation nucleus for the ensuing morphogenesis. The new data can be useful to understand not only the evolutionary novelties occurring in the target taxon but also the morpho‐functional significance of its adaptive collagenic anatomical traits. In addition, data may give insights on both marine collagen sustainable applied researches along with evolutionary and phylogenetic analyses, thus highlighting sponges as a key renewable source for inspired biomaterials. Therefore, we also promote bioresources sustainable exploitation with the aim to provide new donors of marine collagen, thereby supporting conservation of wild populations/species.
“…The functional role of such structures is still unknown. However, these cells clusters closely resemble the strand of cells found until now exclusively in the genus Aplysina (Ereskovsky & Lavrov, 2021; Leys & Reiswig 1998), where these cells have a permanent position along the strands and do not actively move. According to Leys & Reiswig (1998, p. 40) the role of these cellsis primarily to bundle and align the collagen fibrils, creating a pathway that the cells transporting nutrients can recognize and follow, thereby allowing the rapid transport of material to the tip or to the base of the spongeandare suggestive of a primitive nutrient transport pathway in sponge.We follow these ideas and suggest that the cellular clusters of I. retidermata are part of the nutrient transport system towards sponge body districts.…”
Section: Discussionsupporting
confidence: 52%
“…In Ircinia retidermata , a dispersed fibrillar collagenic network is extended throughout the ectosomal/endosomal ECM, as in most demosponges (Ereskovsky & Lavrov, 2021 ; Simpson, 1984 ). These structures mediate cell‐matrix interactions via membrane receptors regulating cell behavior (Exposito et al, 2002 ; Müller, 1997 ) and contribute to build the architecture of the (a) chondrochyma‐like trabecular networks (Cowden & Harrison, 1976 ; sensu Minchin, 1900 ; Stocchino et al, 2021 ), and of (b) walls thickening of aquiferous canals and cavities.…”
In some Porifera (Demospongiae: Keratosa), prototypes of the connective system are almost exclusively based on collagenic networks. We studied the topographic distribution, spatial layout, microtraits, and/or morphogenesis of these collagenic structures in Ircinia retidermata (Dictyoceratida: Irciniidae). Analyses were carried out on a clonal strain from sustainable experimental mariculture by using light and scanning electron microscopy. Histology revealed new insights on the widely diversified and complex hierarchical assemblage of collagenic structures. Key evolutionary novelties in the organization of sponge connective system were found out. The aquiferous canals are shaped as corrugate‐like pipelines conferring plasticity to the water circulation system. Compact clusters of elongated cells are putatively involved in a nutrient transferring system. Knob‐ended filaments are characterized by a banding pattern and micro‐components. Ectosome and outer endosome districts are the active fibrogenetic areas, where exogenous material constitutes an axial condensation nucleus for the ensuing morphogenesis. The new data can be useful to understand not only the evolutionary novelties occurring in the target taxon but also the morpho‐functional significance of its adaptive collagenic anatomical traits. In addition, data may give insights on both marine collagen sustainable applied researches along with evolutionary and phylogenetic analyses, thus highlighting sponges as a key renewable source for inspired biomaterials. Therefore, we also promote bioresources sustainable exploitation with the aim to provide new donors of marine collagen, thereby supporting conservation of wild populations/species.
“…The aquiferous system is a central anatomical and functional structure in a sponge body, responsible for water pumping and filtering. The principal cell type of the aquiferous system is the choanocyte, a cell that bears a single flagellum, surrounded by a collar of microvilli (Ereskovsky and Lavrov, 2021). The choanocytes generate a water flow by the constant beating of their flagella and retain food particles from water by their collars.…”
Section: Introductionmentioning
confidence: 99%
“…The majority of sponges have a leuconoid aquiferous system. Such an aquiferous system is characterized by choanocytes organized in small spherical chambers connected with ambient water by an elaborated net of inhalant and exhalant canals (Leys and Hill, 2012;Ereskovsky and Lavrov, 2021). As much pressure is required to drive water through a long canal system, the choanocyte chambers in leuconoid sponges are subdivided into sealed low-and high-pressure zones (Weissenfels, 1992;Asadzadeh et al, 2019).…”
Section: Introductionmentioning
confidence: 99%
“…In contrast, asconoid and syconoid sponges possess simpler aquiferous system organization with relatively short canal systems and numerous choanocytes lining large cavities (Leys and Hill, 2012;Ereskovsky and Lavrov, 2021). It is thought that they do not need high pressure difference to pump water through their aquiferous system and, consequently, do not have the low-and highpressure zones and corresponding structural features in their choanocyte cavities (Leys and Eerkes-Medrano, 2006;Pozdnyakov and Karpov, 2013;Asadzadeh et al, 2019Asadzadeh et al, , 2020.…”
Background: Tissues of multicellular animals are maintained due to a tight balance between cell proliferation and programmed cell death. Phylum Porifera is an early branching group of metazoans essential to understanding the key mechanisms of tissue homeostasis. This paper is dedicated to the comparative analysis of proliferation and apoptosis in intact tissues of two sponges belonging to distinct Porifera lineages, Halisarca dujardinii (class Demospongiae) and Leucosolenia variabilis (class Calcarea). Results: Labeled nucleotides EdU and anti-phosphorylated histone 3 antibodies reveal a considerable number of cycling cells in intact tissues of both species. The main type of cycling cells are choanocytes -flagellated cells of the aquiferous system. The rate of proliferation remains constant in areas containing choanoderm. Cell cycle distribution assessed by the quantitative DNA stain reveals the classic cell cycle distribution curve. During EdU pulse-chase experiments conducted in H. dujardinii, the contribution of the choanocytes to the total amount of EdU-positive cells decreases, while contribution of the mesohyl cells increases. These findings could indicate that the proliferation of the choanocytes is not solely limited to the renewal of the choanoderm, and that choanocytes may participate in the general cell turnover through migration. The number of apoptotic cells in intact tissues of both species is insignificant. In vivo studies in both species with TMRE and CellEvent Caspase-3/7 indicate that apoptosis might be independent of mitochondrial outer membrane permeabilization. Conclusions: A combination of confocal laser scanning microscopy and flow cytometry provides a quantitative description of cell turnover in intact sponge tissues. Intact tissues of H. dujardinii (Demospongiae) and L. variabilis (Calcarea) are highly proliferative, indicating either high rates of growth or cell turnover. Although the number of apoptotic cells is low, apoptosis could still be involved in the regular cell turnover..
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