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Fig. 5 | Helgoland Marine Research

Fig. 5

From: Reproductive system of the genus Crasiella (Gastrotricha, Macrodasyida)

Fig. 5

Accessory organs of Crasiella diplura (All figures refer to C. diplura except d; ce, g, h are TEM images, a, b, f are DIC images). a The frontal organ containing several spermatozoa. b The caudal organ. The anterior, blind duct surrounded by secretory cells and the posterior, main duct ending in the ‘feeder bib’ extremity (arrow) are clearly visible. c Epithelium of the frontal organ, which surrounds the lumen containing spermatozoa. d Spermatozoa inside the anterior blind duct of the caudal organ in Crasiella sp. e Caudal organ showing the well-developed circular muscles (arrows), the anterior blind duct and the posterior main duct. f Caudal organ in which the accessory duct opening into a large pore (arrow) is visible. g Accessory posterior duct of the caudal organ. The pore (arrow) is visible. h, i Longitudinal (h) and cross-sections (i) of the ‘feeder bib’ extremity of the principal, posterior duct. Note the arrangement of its typical secretion granules (arrows). j Annulated membranes (arrow) in the nucleus of the cells surrounding the principal, posterior duct. k The cytoplasmatic protrusions forming a multi-membranous sheath all over the lumen of the main duct. Note the regular arrangement of the secretion granules (arrow) inside these cytoplasmic protrusions. acd accessory duct, ad anterior blind duct, cm circular muscles, co caudal organ, cp cytoplasmic protrusion, ep epithelium of frontal organ, fo frontal organ, gmr glandulo-muscular region, l lumen, lm longitudinal muscles, md main duct, mr muscular region, s spermatozoon. Scale bars a, b, f = 15 μm; c, d = 2 μm; e, g = 8 μm; hk = 1 μm

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