FIGURE 4. Histological transversal section of O. margoi. A, section of the two lateral post ceca (pca), showing the central posterior intestine (pi) and empty lateral diverticula (ld). Scale bar = 500 µm. B, section trough the male system. The atrium is folded in two parts. The circular posterior part (pp) tied to the celomic cavity trough a connection (cn) and the dorso-ventrally flattened anterior part (ap) ventrally located with a central elongated empty canal (c). On the top of the atrium there is the muscular bulb (mb). Scale bar = 100 µm. C, the two ovaries (ov) containing the ovary cords develops beneath the posterior crop (pc). One of the two ejaculatory ducts (ed) and the ventral located nerve cord (nc) are visible. Scale bar = 100 µm. D, section at the level of the posterior crop (pc) filled with prey's blood. Beneath the posterior crop is possible to observe the two ovaries (o). The ovary on the left shows the terminal part of the egg string with two maturing irregular shaped oocytes (asterisk). On both sides of the posterior crop is visible one pair of testes (t) connected with the body wall trough connections (cn). In the left testis is visible the vasa efferentia (ve) diverting dorsally. Scale bar = 500 µm.

Published as part of Maria Chiara Cascarano, Kleoniki Keklikoglou, Christos Arvanitidis & Pantelis Katharios, 2017, Contribution to the morphological description of the marine leech, Ozobranchus margoi (Apáthy) (Rhynchobdellida: Ozobranchidae) by using combined histology, micro-CT and SEM, pp. 91-108 in Zootaxa 4337 (1) on page 97, DOI: 10.11646/zootaxa.4337.1.4, http://zenodo.org/record/1014198