Proximal-distal anatomical relationships between spermatocysts (Sertoli – germ cell units) and eosinophilic immune system elements in the shark testis: A comparative study of the Greenland shark and thresher shark

Despite lacking a voluminous testis-associated lymphomyeloid tissue (epigonal organ) in adulthood, the far distally located non-spermatogenic tissue of the wild-captured Greenland shark (Somniosus microcephalus) houses loosely circumscribed, granulocyte-liberating epigonal cell patches. These dynami...

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Main Author: Leon Mendel McClusky
Format: Article
Language:English
Published: Elsevier 2025-01-01
Series:Theriogenology Wild
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Online Access:http://www.sciencedirect.com/science/article/pii/S2773093X25000108
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author Leon Mendel McClusky
author_facet Leon Mendel McClusky
author_sort Leon Mendel McClusky
collection DOAJ
description Despite lacking a voluminous testis-associated lymphomyeloid tissue (epigonal organ) in adulthood, the far distally located non-spermatogenic tissue of the wild-captured Greenland shark (Somniosus microcephalus) houses loosely circumscribed, granulocyte-liberating epigonal cell patches. These dynamic patches of epigonal cells are coincident with the differentiation and subsequent distribution of two types of intravascular and extravascular eosinophilic granulocytes in the expansive non-spermatogenic tissue, and in the interstitium of notably premeiotic and meiotic stages of spermatogenesis. Their sparse numbers, discreet occurrence, and as a rule within the vicinity of a blood vessel in all examined tissue samples, including a 1960s archival collection of tissues, are indicative of diapedesis whereupon they become ensconced in the tight interstitial spaces of spermatocysts (stage-synchronized germ and Sertoli cell clones). By comparison, an anatomically robust and intimate testis – epigonal association in the thresher shark does not correlate with any type of granulocyte in the testicular parenchyma nor its vasculature, despite that the most proximal eosinophilic epigonal cells nearly abut the basement membrane of some of its spermatozoal cysts (the only cyst stage to reveal this). These findings in Somniosus are discussed in relation to the previously reported protracted phase of disordered internal cellular organization of the Greenland shark’s spermatogonial cysts due to incompletely differentiated Sertoli supportive functions for what should be well-advancing spermatogonial generations.
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spelling doaj-art-d8a11534b279417eaab46e128bddc5d62025-08-20T03:08:27ZengElsevierTheriogenology Wild2773-093X2025-01-01710012810.1016/j.therwi.2025.100128Proximal-distal anatomical relationships between spermatocysts (Sertoli – germ cell units) and eosinophilic immune system elements in the shark testis: A comparative study of the Greenland shark and thresher sharkLeon Mendel McClusky0Correspondence to: Department of Health & Care, UiT The Arctic University of Norway, Campus Narvik, Lodve Langes gt 2, Narvik 8505, Norway.; Anatomy Section, Department of Health & Care, Faculty of Health Sciences, UiT The Arctic University of Norway, Campus Narvik, NorwayDespite lacking a voluminous testis-associated lymphomyeloid tissue (epigonal organ) in adulthood, the far distally located non-spermatogenic tissue of the wild-captured Greenland shark (Somniosus microcephalus) houses loosely circumscribed, granulocyte-liberating epigonal cell patches. These dynamic patches of epigonal cells are coincident with the differentiation and subsequent distribution of two types of intravascular and extravascular eosinophilic granulocytes in the expansive non-spermatogenic tissue, and in the interstitium of notably premeiotic and meiotic stages of spermatogenesis. Their sparse numbers, discreet occurrence, and as a rule within the vicinity of a blood vessel in all examined tissue samples, including a 1960s archival collection of tissues, are indicative of diapedesis whereupon they become ensconced in the tight interstitial spaces of spermatocysts (stage-synchronized germ and Sertoli cell clones). By comparison, an anatomically robust and intimate testis – epigonal association in the thresher shark does not correlate with any type of granulocyte in the testicular parenchyma nor its vasculature, despite that the most proximal eosinophilic epigonal cells nearly abut the basement membrane of some of its spermatozoal cysts (the only cyst stage to reveal this). These findings in Somniosus are discussed in relation to the previously reported protracted phase of disordered internal cellular organization of the Greenland shark’s spermatogonial cysts due to incompletely differentiated Sertoli supportive functions for what should be well-advancing spermatogonial generations.http://www.sciencedirect.com/science/article/pii/S2773093X25000108TestisGreenland sharkThresher sharkHistologyEpigonal organ cellsEosinophilic granulocytes
spellingShingle Leon Mendel McClusky
Proximal-distal anatomical relationships between spermatocysts (Sertoli – germ cell units) and eosinophilic immune system elements in the shark testis: A comparative study of the Greenland shark and thresher shark
Theriogenology Wild
Testis
Greenland shark
Thresher shark
Histology
Epigonal organ cells
Eosinophilic granulocytes
title Proximal-distal anatomical relationships between spermatocysts (Sertoli – germ cell units) and eosinophilic immune system elements in the shark testis: A comparative study of the Greenland shark and thresher shark
title_full Proximal-distal anatomical relationships between spermatocysts (Sertoli – germ cell units) and eosinophilic immune system elements in the shark testis: A comparative study of the Greenland shark and thresher shark
title_fullStr Proximal-distal anatomical relationships between spermatocysts (Sertoli – germ cell units) and eosinophilic immune system elements in the shark testis: A comparative study of the Greenland shark and thresher shark
title_full_unstemmed Proximal-distal anatomical relationships between spermatocysts (Sertoli – germ cell units) and eosinophilic immune system elements in the shark testis: A comparative study of the Greenland shark and thresher shark
title_short Proximal-distal anatomical relationships between spermatocysts (Sertoli – germ cell units) and eosinophilic immune system elements in the shark testis: A comparative study of the Greenland shark and thresher shark
title_sort proximal distal anatomical relationships between spermatocysts sertoli germ cell units and eosinophilic immune system elements in the shark testis a comparative study of the greenland shark and thresher shark
topic Testis
Greenland shark
Thresher shark
Histology
Epigonal organ cells
Eosinophilic granulocytes
url http://www.sciencedirect.com/science/article/pii/S2773093X25000108
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