Ultrastructure of the excretory system of the marine nematode Monhystera disjuncta.

The excretory system of Monhystera disjuncta is a single ventral gland in the pharyngo-intestinal region. Its ultrastructural morphology is described. The posterior part is swollen, contains the nucleus and many secretory granules. This part gradually narrows anteriorly to form the cell neck, in the apical part of which a valve structure is differentiated. This pear-shaped valve structure opens into a cuticular duct which is embedded in an accompanying cytoplasmic sheath. The cuticular duct opens to the exterior by a pore between the two subventral inner labial papillae.