Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
Review
. 2016 Dec;40(4):1130-1140.
doi: 10.1007/s12639-015-0707-8. Epub 2016 Jan 14.

Nematodes ultrastructure: complex systems and processes

Maha M A Basyoni  1 , Enas M A Rizk  1
Affiliations
Review

Nematodes ultrastructure: complex systems and processes

Maha M A Basyoni et al. J Parasit Dis. 2016 Dec.

Abstract

Nematode worms are among the most ubiquitous organisms on earth. They include free-living forms as well as parasites of plants, insects, humans and other animals. Recently, there has been an explosion of interest in nematode biology, including the area of nematode ultrastructure. Nematodes are round with a body cavity. They have one way guts with a mouth at one end and an anus at the other. They have a pseudocoelom that is lined on one side with mesoderm and on the other side with endoderm. It appears that the cuticle is a very complex and evolutionarily plastic feature with important functions involving protection, body movement and maintaining shape. They only have longitudinal muscles so; they seem to thrash back and forth. While nematodes have digestive, reproductive, nervous and excretory systems, they do not have discrete circulatory or respiratory systems. Nematodes use chemosensory and mechanosensory neurons embedded in the cuticle to orient and respond to a wide range of environmental stimuli. Adults are made up of roughly 1000 somatic cells and hundreds of those cells are typically associated with the reproductive systems. Nematodes ultrastructure seeks to provide studies which enable their use as models for diverse biological processes including; human diseases, immunity, host-parasitic interactions and the expression of phylogenomics. The latter has, however, not been brought into a single inclusive entity. Consequently, in the current review we tried to provide a comprehensive approach to the current knowledge available for nematodes ultrastructures.

Keywords: Electron microscope; Nematodes; Ultrastructure.

PubMed Disclaimer

Figures

Fig. 1
Fig. 1
a–d Wuchereria bancrofti analysis by TEM. a Hypodermal cytoplasm (H) with cellular organelles including endoplasmic reticulum (ER), Golgi apparatus (GA) and mitochondria (head arrow). The muscular layer (M) underlined by lamellae basal (BM) (bar .6 mm). b Transverse section showing cuticle (C), hypodermal cytoplasm (H) with nucleous (N) and glycogen particles (G) (bar 1 mm). c Section showing the cuticle (C), basal layer (asterisk) with membranous projections (thin arrow) oriented toward the hypodermis (H), glycogen particles (G) (bar 1 mm). d Section showing the cuticle (C) with epicuticle (EP), external cortical layer (EC), inner cortical layer (IC), median layer (ML), external fibrous layer (EF), inner fibrous layer (IF), basal layer (asterisk) with membranous projections (thin arrow) emanating towards the hypodermis (H) and muscular layer (M) surrounded by lamellae basal (BM) and endoplasmatic reticulum (ER) (bar 1 mm) (Oliveira-Menezes et al. 2010)
Fig. 2
Fig. 2
Schematic diagram showing layers of the adult cuticle and identified molecular components in each. Sc Surface coat, Ep epicuticle, Co cortical zone, Md medial zone, Bs basal zone (Blaxter and Robertson 1998)
Fig. 3
Fig. 3
Cuticular structures of the pharynx. DIC image of an adult nematode head (lateral view) showing the compartments of the pharynx (black labels) and the various structures found in lumen cuticle lining (white labels). The narrow gap between the two bulbs is the isthmus, and is the location of the nerve ring in the surrounding somatic tissue (Altun and Hall 2012)
Fig. 4
Fig. 4
Head, neck and body wall muscles. a The organization of somatic muscles in the adult C. elegans, dorsal oblique view. The body wall muscles are organized in four quadrants (only the dorsal quadrants are visible) with two rows of cells in each. Bar 50 µm. b Arrangement of head and neck muscles, ventral view. c Arrangement of the somatic tail muscles, ventral view. Original magnification, ×600 (Altun and Hall 2009)
Fig. 5
Fig. 5
Structure of the platymyarian obliquely striated muscle. a Schematic diagram of a body wall muscle cell. Rows of dense bodies (dots) and A bands (thin lines) give the striated appearance macroscopically. Attachment plaques are localized at the end of the terminal half I bands, where the muscle cells in a quadrant contact one another. (Top inset) Layers of tissue from outside (cuticle, top) to inside (muscle, bottom). (Bl) Basal lamina between muscle and hypodermis (Hyp). b Schematic diagram of a wedge of the myofibrillar portion and the muscle belly. The nucleus and the organelles are located within the muscle belly. The myofilament lattice is arranged as a sheet of filaments on the side of the muscle cell that opposes the hypodermis. Contractile units are in register longitudinally; however, they are placed in tandem horizontally, giving rise to an alternating pattern of thick (small yellow dots and lines) and thin filaments (small black dots and lines) bands. The thin filaments are omitted from the lateral and top sides of the drawing. (DB) Dense body (Altun and Hall 2009). (Color figure online)
Fig. 6
Fig. 6
A chemosensory organ located in the anterior region of a nematode (Xiphinema americanum) (Campbell and Reece 2002)
Fig. 7
Fig. 7
a Phasmid (ph) modifications of the cuticle in the posterior end of the body of Rhabdias sp. b Caudal papillae (cp) in the posterior end of body of males nematode parasites of amphibians (González et al. 2012)
Fig. 8
Fig. 8
Aplectana hylambatis, male posterior end. Pap preanal papillae, ptap postanal papillae, s spicules fa fixed articulations, la lateral alae. Scale bar 40 μm (Gonzalez and Hamann 2010)
Fig. 9
Fig. 9
Adult intestine runs parallel to the gonad along the length of the body, ventral view. Differential interference contrast microscopy (DIC) image; magnification ×400 (Altun and Hall. 2012)
Fig. 10
Fig. 10
The hindgut. a Graphic rendition of the structures of the posterior alimentary canal. (Dark ovals) Muscle nuclei.b The lumen of the posterior intestine ends at the rectal valve, composed of two cells (virL and virR). The valve is surrounded by a trilobed rectal gland composed of three cells (rect_D, rect_VL, rect_VR). The gland cells connect to the lumen just posterior to the valve (not shown). The sphincter muscle (Sph mu) surrounds and pierces into the gland. TEM, transverse section; bar 1 μm (Altun and Hall 2012)
Fig. 11
Fig. 11
Differential interference contrast microscopy image of the excretory system in an adult C. elegans. a The excretory gland cell is located on the ventral side between the intestine and the terminal bulb of the pharynx. b The excretory cell nucleus is large and has a “fried egg” appearance with a large nucleolus. c The duct cell is anterior to the excretory cell d The excretory pore cell is ventral to the duct cell. The duct passes through the duct and pore cells and opens outside at the pore. RVG; retrovesicular ganglion (Altun and Hall 2012)
Fig. 12
Fig. 12
Adult male germ line organization. Nomarski DIC picture of an adult male tail region featuring the parts of the reproductive tract, lateral view. DG Distal gonad, PG proximal gonad, DTC distal tip cell, (Altun and Hall 2012)
See this image and copyright information in PMC

Similar articles

See all similar articles

Cited by

See all "Cited by" articles

References

    1. Aboobaker AA, Blaxter ML. Medical significance of Caenorhabditis elegans. Ann Med. 2000;32:23–30. doi: 10.3109/07853890008995906. - DOI - PubMed
    1. Aguinaldo A, Turbeville J, Linford L, Rivera M, Garey J, Raff R, Lake J. Evidence for a clade of nematodes, arthropods and other moulting animals. Nature. 1997;387:489–493. doi: 10.1038/387489a0. - DOI - PubMed
    1. Altun ZF, Hall DH (2009) Muscle system, somatic muscle. Worm Atlas. doi:10.3908/wormatlas.1.7
    1. Altun ZF, Hall DH (2012) Handbook of C. elegans Anatomy. Worm Atlas.http://www.wormatlas.org/hermaphrodite/hermaphroditehomepage.htm
    1. Avery L, Thomas JH (1997) C. elegans, Feeding and defecation In: Riddle DL, Blumenthal T, Meyer BJ (eds.). 2nd ed. Cold Spring Harbor (NY) Laboratory Press, New York - PubMed

LinkOut - more resources