Pieper T, Carpaij M, Reinermann J, Surchev L, Viebahn C, Tsikolia N. Matrix-filled microcavities in the emerging avian left-right organizer.
Dev Dyn 2019;
249:496-508. [PMID:
31729123 DOI:
10.1002/dvdy.133]
[Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2019] [Revised: 10/18/2019] [Accepted: 10/18/2019] [Indexed: 01/14/2023] Open
Abstract
BACKGROUND
Hensen node of the amniote embryo plays a central role in multiple developmental processes, especially in induction and formation of axial organs. In the chick, it is asymmetrical in shape and has recently been considered to represent the left-right organizer. As mechanisms of breaking the initial left-right symmetry of the embryo are still ill-understood, analyzing the node's microarchitecture may provide insights into functional links between symmetry breaking and asymmetric morphology.
RESULTS
In the course of a light- and electron-microscopic study addressing this issue we discovered novel intercellular matrix-filled cavities in the node of the chick during gastrulation and during early neurulation stages; measuring up to 45 μm, they are surrounded by densely packed cells and filled with nanoscale fibrils, which immunostaining suggests to consist of the basement membrane-related proteins fibronectin and perlecan. The cavities emerge immediately prior to node formation in the epiblast layer adjacent to the tip of the primitive streak and later, with emerging node asymmetry, they are predominantly located in the right part of the node. Almost identical morphological features of microcavities were found in the duck node.
CONCLUSIONS
We address these cavities as "nodal microcavities" and propose their content to be involved in the function of the avian node by mediating morphogen signaling and storage.
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