Muscles of the Reproductive System of Male

The copulatory act in Acanthocephala requires a complicated set of responses on the part of the male worm. The muscles associated with these responses include a set of bursal protrusor muscles plus a large bursal depressor muscle which participates in the eversion of the bursa. The anterior and posterior bursal accessory muscles are associated with the bursal depressor muscle and are described for the first time. The bursa itself consists of a unique pattern of radial muscles surrounding a bursal lining or sheath and is in turn surrounded by a loose arrangement of circular muscles. Saefftigen's pouch penetrates the outer covering and empties into the ventral anterior margin of the bursa. This pouch is enclosed by the genital sheath for much of its length. The genital sheath also serves as the site for the origin or insertion for most muscles associated with the reproductive system. An analysis of the histology of the muscles associated with this system indicates that they possess the unique tubelike construction observed throughout this group. The anatomy of Acanthocephala was of interest in the middle to late 19th century to only a few German scientists and may have been the outgrowth of discriminating taxonomic work begun around 1850. Present-day detailed information on the unique internal construction of the "Kratzer" was the result of research by Schneider (1868), Leuckart (1876), Saefftigen (1884), Kaiser (1893) and other early workers. This work has been summarized in reviews by Rauther (1930) and Meyer (1933). More recent work has emphasized other aspects of their biology although an occasional paper such as Whitfield's (1968) has been published on anatomy. General reviews that are more recent are those of Hyman (1951), Baer (1961) and Nicholas (1973). Nevertheless, much remains to be done in the area of general descriptive anatomy of most acanthocephalan species. Most of the original work on the detailed anatomy of Acanthocephala was written in German, and although this work does not describe Moniliformis moniliformis, Kaiser (1893) did compare certain features of M. moniliformis with Macracanthorhynchus hirudinaceus. We attempted the present study because little had been done on the reproductive anatomy of male M. moniliformis. Since most of the available literature was published in the 19th 1 This study was supported in part by Grant NS 08583 from the National Institute of Health and by the Office of Research and Projects at Southern Illinois University. century in German publications, which are difficult to obtain, we have included German terms where appropriate for reference purposes. This study is based on muscles observed in association with the genital sheath and bursa and does not include muscles anterior to the junction of the ligament sac with the genital sheath. Nomenclature for previously described muscles has been taken from Kaiser (1893) for M. hirudinaceus and Kilian (1932) for Oligacanthorhynchus microcephala (Hamanniella microcephala). Materials and Methods Moniliformis moniliformis (M. dubius) was provided through the courtesy of Dr. Frank Fisher, Jr., Rice University. After cleaning, male worms measuring 60-80 mm long were fixed in AFA or in a solution consisting of 0.4 ml formaldehyde, 100 ml water, 0.03 M bromoacetate and 0.18 M sucrose at 0°C as previously described by Dunagan and Miller (1970). Routine paraffin embedding in 56°C wax followed a brief wash of the fixed tissue in physiological saline solution. Sectioning at 8-10 fji and mounting of serial sections was done in the usual manner. Staining was accomplished by the usual methods for H & E, toluidine blue, cresylecht violet and PAS-hematoxylin. The stained sections were photographed on a Leitz microscope. Outline tracings were made and three-dimensional models constructed. Copyright © 2011, The Helminthological Society of Washington 70 PROCEEDINGS OF THE HELMINTHOLOGICAL SOCIETY