Observations on the ultrastructure of the copulatory organ of Archilopsis unipunctata (Fabricius, 1826) (Proseriata, Monocelididae)

Abstract

The copulatory organ in adult specimens of Archilopsis unipunctata has been studied by transmission electron microscopy.This copulatory organ is of the conjuncta-duplex type with eversible cirrus. The seminal vesicle, lined with a nucleate epithelium, is surrounded by spirally arranged muscles. The fibres are enclosed in a sheath that is continuous with the septum of the bulbus and the basement lamina of the male canal epithelium. Distally to the seminal vesicle the bulbus is filled with the secretory cell-necks of the prostate glands. The male canal shows three different parts: seminal duct, ejaculatory duct and eversible cirrus. At the transition of seminal duct and ejaculatory duct two prostate ducts open into the lumen. The structure of the epithelium lining the different parts of the canal is described. The transition into the cirrus may be recognized by an abrupt change in the thickness, the electron density and the stratification in the basement lamina and by the disappearance of the epithelium absent indeed in the cirrus. The material found inside the cirrus-lumen is different according to the zone considered. The origin of this material and of the cirrus teeth is discussed.

Comparative ultrastructure of copulatory organs having a stylet in the Proseriata (Turbellaria)

“…In earlier studies, we have shown that spines in the cirrus of proseriates may have two separate origins : in the Monocelididae (see Martens & Schockaert, 1981 ;E. Martens, 1984b) they are differentiations of the basement membrane; in Cirrifera (Coelogynoporidae) they are intracellular structures (Martens & Schockaert, 1984) .…”

“…unipunctata (see Martens & Schockaert, 1981) . In this new species, the prostate glands discharge their contents into two 'prostatic ducts' which enter the ejaculatory duct, midway between the seminal vesicle and the cirrus.…”

“…oostendensis Martens & Schockaert, 1981, and a new species from the Mediterranean that will be described later. In both species the copulatory organ consisted of a stylet surrounded by long needles (fourteen fine plus two thicker needles in A .…”

“…Martens & Schockaert, 1984), or derivatives of the basement membrane in the Proseriata (E . Martens & Schockaert, 1981 ;E. Martens, 1984b) .…”

Ultrastructure and tubulin immunocytochemistry of the copulatory stylet‐like structure in Childia species (Acoela)

“…Generally, the hard structures of the copulatory organs in lower Bilateria are either intracellular differentiations (e.g. Mainitz, 1977;Lanfranchi, 1978;Ehlers and Ehlers, 1980;Doe, 1982Doe, , 1986Brü ggemann, 1984Brü ggemann, , 1986; see also Rieger et al, 1991) or derivatives of basal lamina (e.g., Martens and Schockaert, 1981;Martens, 1984). Rieger and Doe (1975) were the first to point out this dual nature of sclerotized structures in platyhelminths.…”