Mechanics of cocoon secretion in a segmented worm (Annelida: Hirudinidae)
Ultrastructure published in Micron (2016)
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.
Abstract sourced from PubMed (NCBI) for the cited record. See the original publication for the authoritative version.
Resumen
Transmission electron microscopy of Erpobdella obscura cocoon production reveals concentric-ring secretory granules that fuse and fragment during operculum formation. Provides bioadhesion-relevant insight from a leech model.
Por qué esto importa para la hirudoterapia
El estudio empleó microscopía electrónica de transmisión para examinar cómo los gránulos secretores del cocón forman el opérculo en la sanguijuela Erpodbdella obscura. Describe la liberación coordinada de microgránulos desde células secretoras clitellares posicionadas asimétricamente, gránulos con anillos concéntricos alrededor de un núcleo sin estructura, el transporte a través de túbulos estrechos, la fragmentación en la matriz del opérculo y la fusión en nanoglóbulos y cavidades del opérculo. Para la ASH, esto solo resulta relevante como biología básica de la sanguijuela, ya que se refiere a biomateriales del cocón reproductivo y no a anticoagulantes salivales, al secretoma terapéutico de la sanguijuela ni a la hirudoterapia. El resumen describe hallazgos de microscopía en una única especie de sanguijuela y no aporta datos humanos, clínicos ni terapéuticos.
Citación
Mechanics of cocoon secretion in a segmented worm (Annelida: Hirudinidae).
Rossi AM et al. · Micron (Oxford, England : 1993), 2016
Contexto clínico relacionado
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Añadido a la biblioteca ASH: May 26, 2026 · Última actualización del sitio: 18 de junio de 2026