92 Journal of Nematology, Volume 8, No. 1, January 1976
curate measurements can be made between
the base of the stylet knobs and the dorsal
esophageal gland orifice since projection of
the stylet straightens tile procorpus which
is often coiled,
LITERATURE
CITED
1. CAIRNS, E. J. 1960. M e t h o d s in nentatology:
A review, pages 33-84 in J. N. Sasser attd
W. R. Jenkins, eds. Nematology. University
of N o r t h Carolina Press, C h a p e l Hill.
2. CAVENESS, C. E., a n d F. E. CAVENESS. 1970.
H a t c h i n g response of Meloidogyne incognita
acrita to electrical shock. J. N e m a t o l . 2:294297.
3. CAVENESS, F. E., a n d C, E. CAVENESS. 1970.
N e m a t o d e electroctttion. J. N e m a t o l . 2:298304.
4. L E A R , B., a n d F. C. J A C O B . 1955. Results of
laboratory e x p e r i m e n t s w i t h high-voltage
n o n - t h e r n t a l electrical t r e a t m e n t s for control
of root-knot n e m a t o d e . P l a n t Dis. Rep. 39:
397-399.
5. S T E E L E , A. E., F. E. CAVENESS, a n d C, E.
CAVENESS. 1970. H a t c h i n g response of t h e
sugarbeet n e m a t o d e , H e t e r o d e r a schachtii, to
electrical shock. ]. N e m a t o l . 2:410-411.
Somatic Centrioles in the Parasitic Nematode, Capillaria hepatica
Bancroft, 1893
K. A. WRIGHT l
Nematodes, along with acanthocephalans and rotifers, have classically been considered as being characterized by the developmental p h e n o m e n o n of eutely (cell
or nuclear constancy) (4). Recently, however, an increase in numbers of somatic
muscle cells during post-embryonic develo p m e n t of at least some nematodes (e.g. 6)
has been indicated. Centrioles, the organelles classically associated with cell division in animal cells, have been described
only from sperm of nematodes (2, 5, 7).
Recent studies have determined the morphology (cylinders of nine triplets of tubules with a cartwheel pattern of material
radiating f r o m the center to each of these
triplets) and sequence formation of centrioles, especially from vertebrates and
protozoa. Unfortunately, these studies have
not determined what essential role, if any,
centrioles play in nuclear division (3, 8, 9).
Over the past several years, we have examined most tissues of the adult parasitic
nematode, Capillaria hepatica Bancroft,
1893. Pieces of worms dissected from the
livers of experimentally infected mice were
fixed in 5% glutaraldehyde in 0.066-M
cacodylate
(osmolality 300-350 m0sm.),
Received for publication 1 July 1975.
1 Department of Microbiology and Parasitology, Faculty of
Medicine, University of Toronto, Toronto, Canada,
post-fixed in 1 ~: o s m i u m in cacodylate a n d
embedded in an Epon 8 1 2 - A r a l d i t e 502
mixture. Sections were stained either with a
sequence of uranyl acetate and lead citrate,
or with potassium p e r m a n g a n a t e and lead
citrate.
Only six examples of centrioles were
found: two in n o n g l a n d u l a r cells of the
body wall hypodermis, a pair (at right
angles to each other--a diplosome) in a
lateral h y p o d e r m a l gland cell, one in an
unusual binucleate muscle cell, one in a
myoepithelial cell ensheathing the muscular
esophagus, and one in an epithelial cell of
the vas deferens. Except in the last two instances, the centrioles lay close to the nucleus. One of the centrioles found in a nonglandular cell of tile hypodermis gave the
clearest resolution of its tubule structure
after the section was tilted 15 ° (Fig. 1).
T h e centriole showed nine pairs of doublet
tubules e m b e d d e d within a dense matrix,
but the usual central cartwheel p a t t e r n was
lacking. T h e centriole was a b o u t 0.13 /zm
in d i a m to the outer edge of the doublets.
Other centrioles measured a b o u t 0.10 /xm
in length. T h e s e dimensions are smaller
than those quoted by Fulton (3). T h e
doublet angle (angle of the doublets to a
tangent) was a b o u t 33 °. T h e diam of the
A tubule was a b o u t 20 nm, whereas the B
tubule was a b o u t 22 nm.
Research Notes 93
centrioles) in the intestine of a saprophytic
nero a tode.
Although the role of somatic centrioles
in nematodes is unknown, their rare occurence and incomplete structure should
be r e m e m b e r e d in fttture considerations of
the status of eutely in these animals.
LITERATURE
FIG. I. Centriole lying close to nucleus in a nonglandtdar cell of the body wall of Capillaria
hepatica. Arrow notes nuclear envelop. (X 139,000).
Somatic centrioles in C. hepatica are
rare. I f present, they are unusually small,
incompletely formed, and contain only
doublets. Also, the B tubule is larger than
the A. Centrioles present t h r o u g h o u t
spermatogenesis in the same nematode are
of similar size, but they consist of a circlet
of nine single tubules (7). Similar centrioles
occur in the a m o e b o i d sperm of the nematodes Nippostrongylus brasiliensis (5) and
Ancylostoma duodenale (2). Centrioles
were not located in the sperm of a m a r i n e
nematode, Deontostoma cali[ornicum, although two instances of an irregular b u n d l e
of six and eight single tubules that could
represent r u d i m e n t a r y centrioles (l 1) were
found. Centrioles do not generally occur
elsewhere in nematodes except in modified
form within sense organs. Sensory processes
contain a variety of patterns related to
centrioles, b u t none contain triplets of
tubules. For example, centrioles in sensory
dendrites of Capillaria hepatica have nine
doublets (10), whereas those of Syphacia
obvelata have a high n u m b e r of doublets
arranged a r o u n d the irregular periphery of
the sensory process (I). Zmoray and Guttekova (12) indicate the exceptional presence of functional cilia (presumably with
CITED
1. DICK, T. A.. and K. A. W R I G H T . 1973. T h e
ultrastructure of the cuticle of the nematode, Syphacia obvelata (Rudolphi, 1802).
II. Modifications of the cuticle in the head
end. Can. J. Zool. 51:197-202.
2. FOOR, W. E. 1970. Spermatozoon morphology
and zygote formation in nematodes. Biol.
Reprod. Suppl. 2:177-202.
3. F U L T O N , C. 1971. Centrioles. Pages 170-221.
iu J. Reinert and H. Ursprung, eds. Origin
and continuity of cell organelles. SpringerVerlag.
4. HYMAN, L. H. 1951. T h e Invertebrates:
Acanthocephala, Aschelminthes and Entoprocta. T h e pseudocoelomate bilateria. Mc(;raw Hill, Vol. III.
5. J A M U A R , M. P. 1966. Studies of spermatogenesis in a nematode, Nippostrongylus brasiliensis. J. Cell Biol. 31:381-396.
6. M C L A R E N , D. J. 1972. Ultrastructural studies
on microfilariae (Nematoda: Filarioidea).
Parasitol. 65:317-332.
7. NEILL, B. W., and K. A. W R I G H T . 1973.
Spermatogenesis in the hologonic testis of the
trichuroid nematode, Capillaria hepatica
(Bancroft, 1893). J. Ultrastruct. Res. 44:210234.
8. P I T E L K A , D. R. 1974. Basal bodies and root
structure. Pages 151-192. in M. A. Sleigh, ed.
Cilia and Flagella. Academic Press, New York.
9. WOLFE, J. 1972. Basal body fine structure and
chemistry. Pages 151-192. in E. J. DuPraw,
ed. Advances in Cell and Molecular Biology.
Vol. 2.
10. W R I G H T , K. A. 1974. Cephalic sense organs
of the parasitic nematode, Capillaria hepatica
(Bancroft, 1893). Can. J. Zool. 52:1207-1213.
11. W R I G H T , K. A., W. I). H O P E , and N. O.
JONES. 1973. T h e ultrastructure of the
sperm of Deontostoma californicum, a freeliving marine nematode. Proc. Helminthol.
Soc. Wash. 40:30-36.
12. ZMORAY, I., and A. G U T T E K O V A . 1969.
Ecological conditions for occurrence of cilia
in intestines of nematodes. Biologia 24:97-112.