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Abstract
Girardia biapertura was described with sperm ducts penetrating the penis bulb, subsequently opening separately at the tip of the penis papilla and receiving the abundant secretion of penial glands. In the present work, the penial glands of this species have been histologically and histochemically analysed, and four types of secretory cells are distinguished. The openings of the penial glands into the intrabulbar and intrapapillar sperm ducts, designated here as intrapenial ducts, allow for the distinction between three histologically differentiated regions. The most proximal region possibly corresponds to the bulbar cavity of other freshwater triclads whereas the median and distal portions correspond to the ejaculatory duct. The proximal region of the intrapenial ducts receives mainly the openings of a secretory cell type (type I) that produces a proteinaceous secretion. A second type of secretory cell (type II) that secretes neutral mucopolyssacharides opens into the median region of the intrapenial ducts. The distal portion of the ducts receives two types of secretory cells (types III and IV) which secret glycoprotein and glycosaminoglycans, respectively. Types III and IV open also directly into the male atrium through the epithelium of the penis papilla. A comparison with the results presented here and those of other authors for species of Girardia is provided and the importance of the study of the penial glands for taxonomic characterisation of freshwater triclads is emphasised.
Highlights
The histology and the histochemistry of the glands of the copulatory apparatus of Dugesiidae Ball, 1974 are poorly known
The distal portions of the cell necks of the secretory cells of type I are abundant in the penis bulb and open into the proximal portion of the intrapenial ducts, i.e., just distal to the opening of the sperm ducts into the intrapenial ducts
According to Sluys et al (1997), in G. biapertura the vasa deferentia penetrate the lateral portions of the penis bulb and thereafter expand to form spacious ducts that open separately at the tip of the penis papilla
Summary
The histology and the histochemistry of the glands of the copulatory apparatus of Dugesiidae Ball, 1974 are poorly known. More taxonomic studies reported on the anatomy and histology of the reproductive organs of G. tigrina, G. schubarti, G. anderlani (Kawakatsu & Hauser, 1983), G. arndti (Marcus, 1946), G. rincona (Marcus, 1954), G. festae (Borelli, 1898), and G. anceps (Kenk, 1930) (Kawakatsu et al, 1982, 1983a, b, 1984a, b, 1985, 1986; Sluys, 1992, 1996) In these studies the glands of the reproductive system were only superficially described. A histological study characterising the types of penial glands of G. biapertura and analysing their distribution and their histochemical characteristics, was performed with the following three objectives: (1) to look for the occurrence of local differentiations along the intrapenial ducts (Sluys’ intrabulbar vasa deferentia), (2) to support further studies on the physiology of the male copulatory organs, and (3) to contribute to the taxonomical characterisation of the species
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Schedule a callMore From: Brazilian journal of biology = Revista brasleira de biologia
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