THE “9 + 1” PATTERN OF MICROTUBULES IN SPERMATOZOA OF Mesostoma (PLATYHELMINTHES, TURBELLARIA)

Abstract

Abstract.-The living spermatozoa of the flatworm Mesostoma georgianum have a sperm body about 100 u long and 0.5 , wide, and two motile free flagella, ca. 200 A long. In sections examined with the electron microscope, these flagella have the usual nine pairs of peripheral doublet microtubules and have a single central core unit which is connected to the A members of the doublets by spokelike structures. There are also short connections between the doublets and the flagellar membrane. In material negatively stained with phosphotungstic acid, the doublet microtubules seem to have very different elastic properties than the core; they tend to fall on the copper grids in coils of rather uniform diameter (2-4 ,A), while the core is much more rigid and is often found extending alone, along a relatively straight course, for very long distances (up to 73 1A).After negative staining, the core has a striking appearance with a dense center around which are wound two hollow structures in a double helix of 450 pitch.The center-to-center distance of each gyre is approximately 650 A, and the hollow structures are ca. 180 A in diameter.Observations on patterns of microtubules in spermatozoa which do not have the usual 9 + 2 configuration are undoubtedly of considerable significance with respect to a general theory of flagellar motility. We have for some time been making a systematic survey of such patterns in spermatozoa of turbellarians, and have reported on the occurrence of a 9 + 0 pattern in motile spermatozoa of the acoels Polychoerus,l Childia,2 and Anaperus.3 The present paper is concerned with a "9 + 1" pattern in spermatozoa of a rhabdocoel, Mesostoma georgianum Darlington, 1959, and to our knowledge this is the first report of the occurrence of such a pattern in this order.Other reports of the "9 +

Analytical studies of the ultrastructure and movement of the spermatozoa of freshwater triclads

“…Connections between the microtubules and the cell membrane were observed in the head (Fig. 1B) as has been described for other turbellarians (Silveira & Porter, 1964;Henley et al, 1969;Hendelberg, 1975) and the frog lung fluke (Burton, 1972). In the space between microtubules, board-like structures were sometimes seen (Fig.…”

“…We conjecture also that the connection between the third arm and the flagellar membrane comes about as a result of shrinkage of the diameter of the flagellum, this diameter being smaller after the spermatozoa leave the testis and mature. Henley et al (1969) have diagrammed straight The branching at the distal tip of the flagella of both PO. sapporo and Ph.…”

“…Most reports on the ultrastructure of turbellarian spermatozoa (Klima, 1961;Silveira & Porter, 1964;Henley et al 1969;Franquinet & Lender, 1972;Silveira, 1975;Hendelberg, 1965Hendelberg, , 1975Hendelberg, , 1977Hendelberg, , 1983Hendelberg, , 1986 were made from observations of spermatids and spermatozoa within the testis; few studies have been carried out on mature spermatozoa after their injection into a partner through copulation.…”

Ultrastructural and immunocytochemical investigation of acoel sperms with 9 + 1 axoneme structure: new sperm characters for unraveling phylogeny in Acoela

“…In Trepaxonemata, the central cylinder is made of two helically wound elements (Henley et al 1969;Silveira 1969Silveira , 1975Thomas 1975), while in Childia-Mecynostomidae sperm this structure is represented by a single microtubule and shows no helical pattern in longitudinal sections. Iomini et al (1995) demonstrated that the central axonemal element of Trepaxonemata does not contain tubulin, while the central part of the 9 + 1 axonemal core in C. groenlandica and C. cycloposthium was found to show positive reaction to the three anti-tubulin antibodies used.…”

[A functional flagella with a 6 + 0 pattern]

“…Toutefois des exceptions au sch6ma 9 + 2 ont 6t6 signal6es; elles portent, soit sur le nombre de doublets p6riph6riques (48,2,12,39,47,43,8,65), soit sur le nombre de fibres axiales (57,2,58,13,36,11,26,40,28), soit sur la presence de microtubules ~ l'ext6rieur des doublets p6riph6-riques (2,39,47,40,18,7).…”