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Revisiting a medical case of "stinging" in the human oral cavity caused by ingestion of raw squid (Cephalopoda: Teuthida): New data on the functioning of squid's spermatophores

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Male squid produce intricate spermatophores that, when transferred to the female, undergo the spermatophoric reaction, a complex process of evagination that leads to the attachment of the spermatangium, that is, the everted spermatophore containing the sperm mass. While this process is still not completely understood, the medical literature includes several reports of “oral stinging” (i.e., punctured wounds in the human oral cavity) following consumption of raw male squid, which contains undischarged spermatophores able to inflict such wounds. Here, we revisit a recent medical report of oral stinging by Shiraki et al. (Pathol Int 61:749–751, 2011), providing an in-depth reanalysis of their histological biopsies and revealing vital information on the functioning of squid spermatophores. The morphology of the spermatangia attached within the oral cavity is similar to the condition found in spermatangia naturally attached to female squids. The spermatangia were able to superficially puncture the superficial layers of the oral stratified squamous epithelium, and numerous, minute stellate particles from the squid spermatophore were found adhered to the oral epithelium. These findings corroborate previous hypotheses on the functioning of squid spermatophores, namely that spermatophore attachment generally involves tissue scarification, and that stellate particles play a vital role in the attachment process. Moreover, spermatophore attachment is confirmed to be autonomous (i.e., performed by the spermatophore itself) in another squid species (possibly a loliginid), and the results strongly indicate that the attachment mechanism is not dependent upon a specialized epithelium, nor a mate’s specific chemical stimulus. From the pathological point of view, the best prophylactic measure at present is the removal of the internal organs of the raw squid prior to its consumption.
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... It is possible that the club-like spermatangium cannot firmly attach itself to the oviduct membranes. Due to their small size, sneakerlike spermatangia could presumptively have less anchorage and attachment potential than consort-like ones, given their smaller ejaculatory apparatus and cement body (e.g., Marian, 2012a,b;Marian et al., 2012). If this is the case, then they could be more easily flushed from the female's mantle cavity. ...
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... (Hoving et al., 2004), spermatangia are implanted into female tissue without a specific structure on the oral end of the spermatangium. Recent studies have shown that the ejaculatory apparatus of the spermatophore has numerous stellate particles and that it plays an important role in attaching the spermatangium to female tissue (Marian, 2011(Marian, , 2012a(Marian, , 2012bMarian et al., 2012). Further study of our findings on the intraspecific dimorphism associated with the alternative sperm-attachment sites could help to understand the function and the evolution of spermatangium morphology in cephalopods. ...
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