Mechanics of cocoon secretion in a segmented worm (Annelida: Hirudinidae). Academic Article uri icon

Overview

abstract

  • Clitellate annelids (e.g., segmented earthworms, leeches) secrete proteinaceous cocoons into which eggs are deposited. The process of cocoon production is characterized by the coordinated release of micro-granules from secretory cells positioned asymmetrically within the clitellum. Collectively, these assemble into a tubular cocoon sheath that is sealed at either end by globular opercula. By transmission electron microscopy (TEM), we show here that granules destined to the cocoon operculum in the leech, Erpodbdella obscura, display a series of concentric rings surrounding a structureless core with dimensions approximating a single nanoglobule found in the operculum. Upon their channeling to the surface through narrow tubules, granules are secreted into the cocoon lumen where they appear to fragment upon contact with the operculum matrix. The distribution of partial concentric ring structures throughout the operculum suggests that granular fusion causes dynamic fragmentation of outer surface material, which thereafter integrates into operculum nanoglobules and cavities. Other granules within the same secretory cell display a punctate pattern and likely fuse with the cocoon sheath prior to crystallization.

publication date

  • April 19, 2016

Research

keywords

  • Leeches
  • Secretory Vesicles

Identity

Scopus Document Identifier

  • 84964319064

Digital Object Identifier (DOI)

  • 10.1016/j.micron.2016.04.004

PubMed ID

  • 27129037

Additional Document Info

volume

  • 86