A histochemical study of the reproductive structures in the flatworm Dugesia leporii (Platyhelminthes, Tricladida)

Abstract

Abstract. The functional morphology and the topographic distribution of tissues in the reproductive system of specimens of Dugesia leporii, an endemic Sardinian free‐living planarian, are investigated. Data are provided on the nature of epithelial and glandular secretions, spermatophores, and cocoons by histochemistry, light microscopy, and scanning electron microscopy. All secreting epithelial cells produce strongly acidic sulfated glycoproteins. Glandular cells secrete strongly acidic sulfated glycoproteins or keratohyalin‐like material in the penis bulb, and prekeratin‐like material in atrial glands. Secretions of the bursa copulatrix may be involved in the activation of sperm while material produced by the bursa canal and oviducts probably serves to propel spermatophores or sperm and eggs. Mucous secretion of the seminal vesicle may serve to dilute and activate sperm before copulation. The viscous secrete of the ejaculatory duct and vasa deferentia may play a protective role to maintain sperm viability. Materials produced by the penis papilla and atrium probably lubricate the epithelial surface. The bilayered wall of spermatophore made of keratohyalin‐like material and strongly acidic sulfated glycoproteins is produced by two gland types of the penis bulb. The bilayered shell of cocoon made of prekeratin‐like and keratohyalin‐like materials is secreted by both atrial glands and vitelline cells. The cocoon stalk is made of keratohyalin‐like material produced by cement glands. Shell glands, producing GAG, are not involved in cocoon formation, but they may be implicated in the dilution and activation of seminal material to favor sperm movement toward the oviducts.