Male Alimentary System - Defecation Muscles

<body>  <title>Handbook - Introduction</title> <META name="Description" content="WormAtlas: A database of behavioral and structural anatomy of Caenorhabditis elegans."> <META name="KeyWords" content="Caenorhabditis, elegans, anatomy, hermaphrodite, worm, nematode">  <META http-equiv="Content-Type" content="text/html; charset=iso-8859-1"> <META name="Copyright" content="www.wormatlas.org"> <link rel="StyleSheet" href="../../css/common-style.css" type="text/css"> <link rel="StyleSheet" href="../../css/gray.css" type="text/css"> <link rel="StyleSheet" href="../../css/gray-menu.css" type="text/css"> <script language="JavaScript" type="text/javascript" src="../../css/css.js"></script> <script language="JavaScript" type="text/javascript" src="../../javascripts.js"></script> <script language="JavaScript" type="text/javascript" src="../../pop-closeup.js"></script> <style type="text/css">  </style> </head> <BODY BGCOLOR="#FFFFFF" TEXT="#000000">  <table cellpadding="0" cellspacing="0" border="0" width="100%"> <tr><td align="center" valign="top"> <a name="top"></a>  <table cellpadding="0" cellspacing="0" border="2" width="100%"><tr> <td background="../../art1/oldheadercolor.jpg" class="pictbackground"><img src="../../ART1/headerA2b.jpg" width="829" height="86" border="0" usemap="#Map2"> </td> </tr><tr class="printhide"><td class=""> </td></tr></table>  <script language="JavaScript" type="text/javascript" src="menu.js"></script>  <table cellpadding="0" cellspacing="0" border="0" width="100%"> <tr> <td width="1051" align="left" valign="top" class="shadow-horizontal"> <br> <br>  <table cellpadding="5" cellspacing="0" border="0"> <tr> <td align="left" valign="top" class="just">  <span class="title"><span class="style5"><a name="Alimentarysystemdefecationmuscles" id="Alimentarysystemdefecationmuscles"></a>ALIMENTARY SYSTEM OF THE MALE </span>- DEFECATION MUSCLES </span>  <center> <TABLE align="left" cellpadding="0" cellspacing="0" class="gallerytext"> <tr> <td width="1169" align="left" background="#Chinsang2000" class="style1"><span class="subtitle"><a name="Sphinctermuscles1" id="Sphinctermuscles1"></a></span><span class="style10"><br> 1 Sphincter Muscles </span> <p>As described in<a href="../muscleintro/Musintroframeset.html" target="_blank"> Male Muscles - Overview</a>, the sphincter (sph), like the anal depressor, is a sexually dimorphic muscle, common to both sexes but modified during male larval development (<a href="#MaleAlimFIG1">MaleAlimFIG 1</a>).</p> <div align="center"><img src="images/MaleAlimFIG1.jpg" alt="MaleAlimFIG 1 Sphincter muscles" name="MaleMusFIG43" width="717" height="187" border="0" align="middle" class="Galborder" id="MaleAlimFIG1"><a name="MaleAlimFIG1" id="MaleAlimFIG1"></a> </div> <span class="picturetitle">MaleAlimFIG 1: Sphincter muscles. </span><span class="style2">Illustration of the adult male tail region featuring the sphincter muscle (sph), left lateral view. Sexually dimorphic muscles are underlined.</span> <p>In the adult male the alimentary tract and reproductive tract are joined to a common chamber, the cloaca, which opens to the environment at the anus (described in detail in <a href="../alimproct/Procframeset.html" target="_blank">The Proctodeum</a>). In contrast to the hermaphrodite anus, the male cloaca is constitutively open presumably to permit free movement of the spicules (housed within) and sperm during mating behavior. The principal seal for the male alimentary tract is instead at the sphincter (<a href="#MaleAlimFIG2">MaleAlimFIG 2</a>).</p> <div align="center"><img src="images/MaleAlimFIG2.jpg" alt="MaleAlimFIG 2 Positioning of the sphincter" name="MaleAlimFIG2" width="800" height="306" border="0" align="middle" class="Galborder" id="MaleAlimFIG2"><a name="MaleAlimFIG2" id="MaleAlimFIG2"></a> </div> <span class="picturetitle">MaleAlimFIG 2: Positioning of the sphincter. </span><span class="style2"><strong>A. </strong>Epifluorescent image from transgenic animal expressing the<em> <a href="http://www.wormbase.org/species/c_elegans/gene/WBGene00001184" target="_blank">egl-15</a></em> reporter gene (FGF receptor), lateral right medial plane. The sphincter muscle (sph) and nucleus are proximate to the spicules and rectal gland. (Strain source: C. Branda and M. Stern.) <strong>B. </strong>Diagram showing the position of the sphincter muscle in the male tail. (PAG) Pre-anal ganglion. </span> <p>The male sphincter is tonically contracted and must be relaxed (through<a href="http://www.wormbook.org/chapters/www_gaba/gaba.html#sec2_3" target="_blank"> inhibitory GABA transmission</a>) during <a href="http://www.wormbook.org/chapters/www_intestine/intestine.html#sec5_3" target="_blank">defecation</a>. This response to GABA is opposite to that observed in larval males and in adult hermaphrodites and may reflect a change in receptor expression in the muscle (<a href="#Reiner1995">Reiner and Thomas, 1995</a>). The male sphincter also differs morphologically from larval male and hermaphrodite sphincters. It is enlarged (hypertrophied) but still contains a single sarcomere. It has a dorsal process that attaches to the dorsal roof and that contains myofilaments (<a href="#MaleAlimFIG3">MaleAlimFIG 3</a>). Thus hyper-contraction of the sphincter during ejaculation not only clamps off the intestine but also draw it away from the vas deferens, possibly allowing sperm to pass more freely (<a href="#Sulston1980">Sulston et al., 1980</a><a href="http://www.wormatlas.org/ver1/Sulston%20postembmale_1980/toc.html" target="_blank"></a>). </p> <div align="center"><img src="images/MaleAlimFIG3.jpg" alt="MaleAlimFIG 3 Ultrastructure of the sphincter muscle" name="MaleAlimFIG3" width="800" height="565" border="0" align="middle" class="Galborder" id="MaleAlimFIG3"><a name="MaleAlimFIG3" id="MaleAlimFIG3"></a> </div> <span class="picturetitle">MaleAlimFIG 3: Ultrastructure of the sphincter muscle. </span><span class="picturetitle style2"><strong>A.</strong> Low-power TEM featuring the sphincter muscle. (PAG) Pre-anal ganglion; (v/dsrL/R) ventral and dorsal spicule retractors, (v/dspL) ventral and dorsal spicule protractors; (d/vBWM) dorsal and ventral body wall muscle (Image source: N2Y [MRC] 596-24.) <strong>B. </strong>TEM of boxed area in <strong>3A</strong> showing close up of the myosin and actin filaments within the sphincter muscle. (N) Nucleus. (Image source: N2Y [MRC] 942-L.)</span> <hr class="page-splits"> <p><span class="subtitle"><a name="Celllist2" id="Celllist2"></a></span><span class="style10"><br> 2 Cell List</span></p> <p><strong>Anal sphincter muscle </strong><br> <a href="http://www.wormbase.org/species/all/anatomy_term/WBbt:0005798" target="_blank">mu sph</a> <br> <strong>Anal depressor muscle</strong><br> <a href="http://www.wormbase.org/species/all/anatomy_term/WBbt:0004292" target="_blank">mu anal</a></p> <hr class="page-splits"> <p><span class="subtitle"><a name="References3" id="References3"></a></span><span class="style10"><br> 3 References</span></p> <p><a name="Branda2000"></a>Branda, C.S. and Stern, M.J. 2000. Mechanisms controlling sex myoblast migration in <em>Caenorhabditis elegans</em> hermaphrodites. Dev. Biol. <strong>226:</strong> 137-51. <a href="http://dx.doi.org/10.1006/dbio.2000.9853" target="_blank">Article</a></p> <p><a name="Garcia2001"></a>Garcia, L.R., Mehta, P. and Sternberg, P.W. 2001. Regulation of distinct muscle behaviors controls the <em>C. elegans</em> male's copulatory spicules during mating. Cell <strong>107</strong>: 777-788. <a href="http://dx.doi.org/10.1016/S0092-8674(01)00600-6" target="_blank">Article</a></p> <p><a name="Liu1995"></a>Liu, K.S. and Sternberg, P.W. 1995. Sensory regulation of male mating behavior in <em>Caenorhabditis elegans</em>. Neuron <strong>14</strong>: 79-89. <a href="http://dx.doi.org/10.1016/0896-6273(95)90242-2" target="_blank">Article</a></p> <p><a name="Reiner1995"></a>Reiner, D.J. and Thomas, J.H. 1995. Reversal of a muscle response to GABA during <em>C. elegans</em> male development. J. Neurosci. <strong>15:</strong> 6094-6102. <a href="http://www.jneurosci.org/content/15/9/6094.long" target="_blank">Article</a></p> <p><a name="Sulston1980"></a>Sulston, J.E., Albertson, D.G. and Thomson, J.N. 1980. The <em>Caenorhabditis elegans</em> male: Postembryonic development of nongonadal structures. Dev Biol. <strong>78</strong>: 542-576. <a href="http://www.wormatlas.org/ver1/Sulston postembmale_1980/toc.html" target="_blank">Article</a></p> <hr class="page-splits"></td> </tr><tr> <td align="left" class="style1"> <a href="#top"><img src="../../picts/topoff.gif" border="0" onMouseOver="this.src='../../picts/topon.gif'" onMouseOut="this.src='../../picts/topoff.gif'"> </a><br> This chapter should be cited as: Lints, R. and Hall, D.H. 2009. Male alimentary system, defecation muscles. In<em> WormAtlas</em>.  doi:<a href="http://dx.doi.org/10.3908/wormatlas.2.3" target="_top">10.3908/wormatlas.2.3 </a> <br> Edited for the web by Laura A. Herndon. 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