Functional and 3D Ultrastructural Characteristics of a Cement Gland in a Giant Danio (D. cf. malabaricus)

Abstract

Cement glands are transient ectodermally‐derived adhesive organs found in the larval stage of several aquatic species. We have identified a transient structure on the apical aspect of a giant danio (Devario cf. malabaricus) head, a member of the danioninae subfamily of cyprinids. We hypothesize that this structure is a cement gland (CG), the primary adhesive organ of the giant danio (GD), and that its cellular components support its function. Using a novel adhesion assay, transmission electron microscopy (TEM), scanning electron microscopy (SEM), and serial block face‐scanning electron microscopy (SBF‐SEM), we investigated the function of the CG and the structures of the cells that constitute it. Our studies have shown that the gland produces a glycoconjugates‐containing mucus that allows larvae to attach to surfaces in their environments. The larvae remain attached until day 5 when they begin swimming. Lectin staining and SEM revealed that the CG is composed primarily of goblet and epithelial cells organized in a lattice‐like pattern. These studies also show that the CG disappears by week 2. TEM confirms that the CG consists of elongated goblet cells containing granules of varying electron densities. These cells are framed apically by intercalated epithelial cells, and basally by a layer of squamous epithelium. Finally, we used SBF‐SEM and Amira 6 to reconstruct the three dimensional spatial relationship of these cells. To our knowledge, this is the first functional and ultrastructural study of a CG in a danioninae. Our results suggest that the cement gland is an important organ in GD development.Support or Funding InformationDePauw FDC, SRF, Faculty FellowshipThis abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.