Ultrastructure of spermiogenesis and the spermatozoon of Raillietina (raillietina) tunetensis (Cyclophyllidea, Davaineidae), intestinal parasite of turtle doves in Senegal

International

Pergamon

Journalfor Paradrology, Vol. 24, No. 2, pp. 237-248, 1994 Copyright 0 1994 Australian Society for Parasitology Elsevier Science Ltd Printed in Great Britain. All rights reserved 002&7519/94 $7.00 + 0.00

ULTRASTRUCTURE OF SPERMIOGENESIS AND THE SPERMATOZOON OF RAILLIETINA (RAILLIETINA) TUNETENSIS (CYCLOPHYLLIDEA, DAVAINEIDAE), INTESTINAL PARASITE OF TURTLE DOVES IN SENEGAL CHEIKH TIDIANE BA* and

BERNARD MARCHAND

Laboratory of Parasitology, Department of Animal Biology, Faculty of Sciences, Cheikh Anta Diop University Dakar,

Dakar,

of

Senegal

(Received 6 April 1993; accepted 26 August 1993)

Abstract-B,4 C. T. and

MARCHAND

B. 1994. Ultrastructure

of spermiogenesis

and the spermatozoon

of

Raiileitina (Raillietina) tunetensis (Cyclophyllidea, Davaineidae), intestinal parasite of turtle doves in Senegal. International Journal for Parasitology 24: 231-248. Spermiogenesis in Raillietina (Raillietina) tunetensis begins with the formation of a differentiation zone equipped with cortical microtubules and containing two centrioles. One of the centrioles very rapidly gives rise to a flagellum which fuses with a median cytoplasmic extension, the cortical microtubules elongate and arched membranes appear. After the migration of the nucleus two crest-like bodies form and the old spermatid becomes detached from the residual cytoplasm. The mature spermatozoon of R. (R.) tunetensis exhibits an apical cone of electron-dense material and two helicoidal crest-like bodies 100 to 200 nm thick. The cortical microtubules are spiralized and make an angle of about 60” to the spermatozoon axis. The axoneme is of the 9 + “1”pattem and does not reach the posterior extremity of the gamete. The nucleus is a fine, compact cord wound in a spiral which may make as much as two complete coils round the axoneme. The cytoplasm is electron-dense in region V of the spermatozoon. Over the rest of the gamete it is made up of lucent material divided into irregular compartments by electron-dense material. The latter consists of a fine, discontinuous peri-axonemal sheath, a fine granular sub-microtubular layer situated in regions I and II, and irregularly spaced partitions localized in regions III and IV. A nucleus with an annular cross section has never been described in a cestode spermatozoon; nor have two crest-like bodies of different length and thickness. In addition we report for the first time the existence of crest-like bodies in the Davaineidae. INDEX KEY WORDS: Raillietina (Railliefina) tunetensis; spermatozoon; turtle doves, Cyclophyllidea; Davaineidae; Senegal.

THE

order

INTRODUCTION Cyclophyllidea alone comprises

spermiogenesis;

ultrastructure;

Allison, 1977; Robinson & Bogitsch, 1978; BB & Marchand, 1992b, 1993), two Taeniidae (Morseth, 1969; Featherston, 1971) one Nematotaeniidae (Mokhtar-Maamouri & Azzouz-Draoui, 1990), one Catenotaeniidae (Swiderski, 1970), one Dilepididae (Ribicka, 1962) and one Davaineidae (Swiderski, Z. 1984. Abstract in Proceedings of the Electron Miscroscopy Society of Southern Africa 14: 131-132). In the present work we describe the ultrastructure of spermiogenesis and the spermatozoon of a second species of the Davaineidae, Raillietina (Raillietina) tunetensis.

more

species than all the other orders of cestodes together. It has been subdivided into 13 families (Schmidt, 1986). To our knowledge only 18 species belonging to 7 families have been the subject of ultrastructural studies of spermiogenesis and/or the spermatozoon. These are: eight Anoplocephalidae (Swiderski, 1968; Mackinnon & Burt, 1984; B& Marchand & Mattei, 1991; BB & Marchand, 1992a,c, 1994inpress a,b), four Hymenolepididae (Rosario, 1964; Lumsden, 1965; Swiderski, 1970; Sun, 1972; Kelsoe, Ubelakker &

MATERIALS AND METHODS Our specimens

were gathered live from the small intestine of Streptopeliu senegulensis (Laughing Dove) then kept alive in a 0.9%0 NaCl solution. We identified them, following Schmidt’s classification, as belonging to the species Raillietina (Raillietina) tunetensis, the only species reported in

*To whom all correspondence should be addressed at: Laboratoire de Parasitologie, Departement de Biologie animale, Facultt des Sciences, Universite Ch. A. Diop de Dakar, Senegal. 231

238

C. T. BA and B.

MARCHAND

Senegal in Streptopeliu by Vassiliades (1980). Seminal vesicles and testes were removed under a binocular microscope, then fixed for 24 h at 4°C with 2.5% glutaraldehyde in a 0. I M sodium cacodylate buffer at pH 7.2, post-fixed for 1 hat 4’C with 1% osmium tetroxide in the same buffer, then dehydrated with ethanol and propylene

differentiation zone. Then the ring of arched membranes narrows to strangulation point resulting in the detachment of the spermatid from the residual cytoplasm (Figs. 7 and 21d).

oxide before being embedded in epon. Ultrathin sections were cut on a Reichert-Jung Ultracut E ultramicrotome, then stained with uranyl acetate and lead citrate. They were examined in Siemens Elmiskop 101 and JEOL 100 C X II electron microscopes.

From anterior to posterior of the spermatozoon we were able to distinguish five regions (I-IV) without any clear morphological discontinuity between them but exhibiting distinctive ultrastructural characters. Region I (Figs. 11, 12, 16 and 221) is roughly 0.300.40 m wide. It exhibits an apical cone of electrondense material, roughly 0.30 q wide at its base, and two helicoidal crest-like bodies of different length and varying in thickness from 100 to 200 nm. The cortical microtubules form a continuous layer of dense, submembranous material. The central axoneme is surrounded by a fine discontinuous sheath of electrondense material and lucent cytoplasm. The latter exhibits small granules of electron-dense material forming a discontinuous layer under the microtubules (Fig. 12). Region II (Figs. 13, 17 and 2211) has a maximum width of 0.40 m. It lacks crest-like bodies but exhibits a central axoneme and electron lucent cytoplasm containing dense material forming a discontinuous peri-axonemal layer and a peripheral granular layer which is also discontinuous and situated under the cortical microtubules. These are spiralized and appear in longitudinal and cross sections as continuous dense sub-membranous material. Region III (Figs. 13, 14, 18 and 22111) is roughly 0.40 to 0.50 jnn wide. The central axoneme is surrounded by a fine layer of lucent cytoplasm and a continuous sheath of electron-dense material. The cytoplasm is electron-lucent and subdivided into several compartments by irregularly spaced partitions of electron-dense material which join the fine sheath of dense peri-axonemal material to the spiralized cortical microtubules (Figs. 13, 17 and 18). The angle of spiralization of the microtubules (Fig. 13) with the spermatozoon axis is about 60”.

RESULTS Spermiogenesis The young R. (R.) tunetensis spermatid exhibits a roughly circular nucleus with partially condensed chromatin (Fig. 1). The beginning of spermiogenesis is marked by the formation of a differentiation zone which comprises sub-membranous cortical microtubules, two centrioles and a median cytoplasmic extension (Figs. 1,2,8 and 2 1a) equipped on the inside with cortical microtubules (Fig. 1). One of the centrioles very rapidly forms a flagellum (Figs. 2, 3, 4 and 7). The cortical microtubules elongate and spiralize and arched membranes appear at the front of the differentiation zone (Figs. 3 and 21b). The nucleus, which remains outside the ring of arched membranes, takes on a conical shape (Fig. 4). It then undergoes considerable elongation, becomes filiform, exhibits fibrous chromatin and migrates in the spermatid body (Figs. 5 and 21~). At this stage of differentiation, granules of electron-dense material appear in the cytoplasm and form a discontinuous layer under the cortical microtubules (Fig. 9). During its migration the nucleus more or less completely envelopes the axoneme, moves aside the cortical microtubules and comes into close contact with the plasma membrane (Fig. 6). Thus in cross section it is partly or entirely surrounded by the sub-membranous cortical microtubules, according to the point at which the section is cut (Figs. 9 and 10). At the end of spermiogenesis two helicoidal crest-like bodies appear at the front of the

FIG. 1. Longitudinal

FIG. 2. Longitudinal

Spermatozoon

section of a differentiation zone ofa young spermatid of Raillietina (Raillietina) tuneiensis through the two centrioles (C). Cm = cortical microtubules; N = nucleus. Bar = 1 p.

one of

and cross sections of the distal part of a differentiation zone. B=cytoplasmic bud; C=centriole; Ce = cytoplasmic extension; Cm = cortical microtubules; F = flagellum. Bar = 0.5 rsn.

FIG. 3. Longitudinal section of a differentiation zone. The two centrioles are parallel but do not start at the same level. Am = arched membrane; C = centriole; Cm = cortical microtubules; F = flagellum. Bar = 0.5, /.an. FIG. 4. Longitudinal section of a differentiation zone. Just before its migration in the spermatid body, the nucleus(N) conical shape outside the ring of arched membranes (Am). Ax = axoneme; C = centriole; Cm = cortical microtubules. Pm.

exhibits a Bar = 0.5

Spermiogenesis and spermatozoon

of R. (R.) tunetensis

239

240

C. T. BK and B. MARCHAND

Region IV (Figs. 14, 18 and 221V) has a maximum width of 0.50 m. It is marked by the presence of the nucleus. The latter is a fine compact cord coiled in a spiral round the axoneme. It envelops the axoneme once or twice, interposes itself between the cortical microtubules and comes into close contact with the plasma membrane. Thus in cross section, depending on the point where the section was cut, it forms one or two coils and appears partially or entirely surrounded by the cortical microtubules, (Fig. 18). These appear in longitudinal section (Fig. 14) and cross section as a layer of dense sub-membranous material. The cytoplasm is electron-lucent. Region V (Figs. l&19,20 and 22V) is between 0.10 and 0.50 q in width. It is marked by the disorganization then the disappearance of the axoneme, the peri-axonemal sheath and the intracytoplasmic partitions of electron-dense material (Figs 19 and 20). The cytoplasm which is electron-lucent where this region begins (Fig. 19), becomes very electron-dense at the posterior extremity of the gamete (Figs. 15 and 20) where the cortical microtubules are parallel to the spermatozoon axis (Fig. 15).

DISCUSSION Spermiogenesis in cestodes usually begins with the formation of a differentiation zone bordered by cortical microtubules and containing two centrioles. However, we have demonstrated the presence of a single centriole in the differentiation zone of the young Hymenolepis nana spermatid, the second being situated outside the ring of arched membranes (Ba & Marchand, 1992b). These centrioles are associated either with striated roots and an intercentriolar body, or with striated roots only, or with a centriolar adjunct

only (BI & Marchand, in press a). The position of these centrioles in relation to each other varies according to the species: In a Haplobothrioidean (Mackinnon & Burt, 1985), a Pseudophyllidean (Swiderski & Mokhtar-Maamouri, 1980), two Diphyllidean (Azzouz-Draoui & Mokhtar-Maamouri, 1986), four Tetraphyllidea-Onchobothriidae (MokhtarMaamouri & Swiderski, 1975; Mokhtar-Maamouri, 1982; Mahendrasingam, Fair-weather & Halton, 1989) and a Proteocephalidean (Swiderski, 1985. Abstract in Proceedings of the Electron Microscopy Society of Southern Africa 15:181-182), they are in a line one in

front of the other, separated by an intercentriolar body. On the other hand, in a species of the Tetraphyllidea-Phyllobothriidae Phyllobothrium gratile as shown by Mokhtar-Maamouri (1979) and two Cyclophyllidea, Namatotaenia chantalae by MokhtarMaamouri & Azzouz-Draoui (1990) and H. nana by Ba & Marchand (1992b), the centrioles are in an orthogonal position. In P. gracile they are separated from each other by an intercentriolar body whereas in N. chantalae and H. nana no intercentriolar structure exists. In two other Cyclophyllidea, Thysaniezia ovilla as demonstrated by Ba et al. (1991) and Mathevotaenia herpestis by BI & Marchand (in press a) the centrioles are parallel to each other. In Th. ovilla they are surmounted by dense, finely granular material while in M. herpestis they are flanked by striated roots. R. (R.) tunetensis does exhibit two parallel centrioles like most of the other cestodes, but it nevertheless differs from them since its centrioles are longitudinally positioned in relation to each other and are never associated with striated roots, an intercentriolar body or dense, granular material. In the cestodes migration of the nucleus usually takes place towards the end of spermiogenesis. The

FIG. 5. Longitudinal section of a differentiation zone of Railletina (Raillietina) tunetensis. the nucleus (N) migrates around the axoneme (Ax). Am = arched membrane; Cm = cortical microtubules. Bar = 0.5 m. FIG. 6. Longitudinal section of a differentiation zone. The nucleus (N) completely envelops the axoneme (Ax). Cm = cortical microtubules; P = plasma membrane. Bar = 0.5 m. FIG. 7. Longitudinal section of an old spermatid. Am = arched membrane; Bar=

Cb = crest-like

body;

Rc = residual

cytoplasm.

1~.

FIG. 8. Cross section of cytoplasmic extensions (Ce) and flagella(F) situated at the distal part of the differentiation beginning of spermiogenesis. Cm = cortical microtubule; B = cytoplasmic bud. Bar = I pm.

FIG. 9. Cross section of a spermatid

showing the nucleus (N) entirely surrounded by cortical electron-dense material. Bar = 1 pm.

FIG. 10. Cross section of a spermatid

showing

the nucleus (N) partly surrounded

by cortical

microtubules.

microtubules

zones at the

G = granules

(Cm). Bar = 1 p.

of

Sperrniogenesis and spermatozoon

of R. (R.) tunetensis

241

C. T. BA and B. MARCHAND

242 nucleus

exhibits

at this

point

a partially

condensed

coils or not around the axoneme or the two axonemes of the old spermatid. In a Pseudophyllidean, Bothriocephalus clavibothrium as shown by Swiderski & Mokhtar-Maamouri (1980), a Diphyllidean, Echinobothrium afine by AzzouzDraoui & Mokhtar-Maamouri (1986) and a species of the Tetraphyllidea-Onchobothriidae, Acanthobothrium jlicolle var. jiicolle by Mokhtar-Maamouri (1982) the nucleus lies along the axonemes and exhibits in cross section a roughly circular contour. On the other hand in the Cyclophyllidea, Nematotaenia chantalae as demonstrated by Mokhtar-Maamouri & Azzouz-Draoui, 1990), Th. ovilla by BI et al. (1991), H. nana by Bb & Marchand (1992b), Mathevotaenia herpestis by BB & Marchand, (in press a) and Aporina delafondi by BP & Marchand (1994), the nucleus coils in a more or less tight spiral around the axoneme. In N. chantalae and M. herpestis it interposes itself between the cortical microtubules and comes into close contact with the plasma membrane. Thus in cross section it appears to be crescent-shaped. Our material differs chromatin

and either

FIG. Il. Longitudinal

here again by the fact that the nucleus may completely envelop the axoneme and exhibit an annular cross section. To our knowledge no cestode spermatid has yet been described showing such a conformation of the nucleus. In many cestodes the arched membranes appear at the front of the differentiation zone and at the beginning of spermiogenesis (Mokhtar-Maamouri & Swiderski, 1975; Robinson & Bogitsch, 1978; Mokhtar-Maamouri, 1979; Swiderski & Mokhtar-Maamouri, 1980; Mokhtar-Maamouri, 1982; Swiderski, 1985. Abstract cited above; Swiderski, Z. 1986. Abstract in Proceedings of the XZth International Congress of Electron Microscopy, Kyoto 2959-2960; Azzouz-Draoui & Mokhtar-Maamouri, 1986; Mahendrasingam et al., 1989; Mokhtar-Maamouri & Azzouz-Draoui, 1990; B1 et al., 1991; BB & Marchand, 1992b, in press a). However in the Cyclophyllidean Aporina delafondi, we were able to show the temporary appearance of these formations at the distal extremity of the differentiation zone of the young spermatids (Bd & Marchand, 1994). In

section of region I of the mature Railtietina (Raihiefina) tunetensis spermatozoon. Ax = axoneme; Cb = crest-like bodies; Cm = cortical microtubules. Bar = 1 w.

AC = apical cone;

FIG. 12. Longitudinal section of regions I and II of the mature R. (R.) funeiensis spermatozoon. Cb=crest-like body; Cm = cortical microtubules; G = granules of electron-dense material; Sh = sheath of electron-dense peri-axonemal material. Bar= 1 m. FIG. 13. Longitudinal

Sh = sheath

section of regions II and III of the mature R. (R.) tunetensis spermatozoon. Cm = cortical microtubules; of electron-dense peri-axonemal material; W = wall of intracytoplasmic electron-dense material. Bar = 1 m.

FIG. 14. Longitudinal

section of regions III and IV of the mature R. (R.) tunetensis spermatozoon. Cm = cortical microtubules; N = nucleus. Bar = 1 m.

FIG. 15. Longitudinal

section of region V of the mature R. (R.) tunetensis spermatozoon. dense. Cm= cortical microtubules. Bar= 1 mn.

C = lucent cytoplasm;

The cytoplasm

FIG. 16. Cross sections of region I of the mature R. (R.) tunetensis spermatozoon. It exhibits two crest-like and short (arrows), the other is long and thick (arrowheads). Bar= 1 m. FIG. 17. Cross section of region II of the mature R. (R.) funetensis spermatozoon. dense peri-axonemal material. Bar = 0.5 p. FIG. 18. Cross sections of regions III and IV of the mature R. (R.) tunetensis Cm = cortical microtubules; N = nucleus; Sh = sheath of electron-dense peri-axonemal electron-dense material. Bar = 0.5 m.

Ax = axoneme;

becomes

electron-

bodies. One is thin

Sh = sheath of electron-

spermatozoon. C=lucent cytoplasm; material; W = wall of intracytoplasmic

FIG. 19. Cross section of region V of the mature R. (R.) tunetensis spermatozoon. The axoneme becomes disorganized. Its doublets are simplified and become singlets (S). Sh=sheath of electron-dense pcri-axonemal material; W = wall of intracytoplasmic electron-dense material. Bar = 0.5 m. FIG. 20. Cross section of region V of the mature R (R.) tunetensis spermatozoon. After the axoneme stops, the walls of intracytoplasmic electron-dense material and the sheath of electron-dense peri-axonemal material disappear. The cytoplasm (C) becomes very electron-dense. Bar = 0.5 p.

Spermiogenesis and spermatozoon

of R. (R.) tunetensis

243

244

C. T. BA and B. MARCHAND

____________________--------

L$/ N

Cm C

\ -

B Ce

F

Cm F

~

II

a

Am

b

?!I

\\

Cm

d FIG. 21(a-d). Attempted reconstruction of the main stages of spermiogenesis of Railiietina (Raillietina) tunetemis. (a) Organization of the differentiation zone at the beginning of spermiogenesis. (b) Rapid formation of a flagellum, difference in level of the centrioles and appearance of arched membranes. (c) Migration of the nucleus in the body of the spermatid. (d) Appearance of the crest-like bodies followed by a constriction of the ring of arched membranes (arrowheads), then the separation of the old sperrnatid from the residual cytoplasm. To make the diagram clearer, the spiral coil of the cortical microtubules has not been shown. Am = arched membranes; B = cytoplasmic bud; C = centriole; Cb = crest-like bodies; Ce = cytoplasmic extension; Cm = cortical microtubules; F = flagellum; N = nucleus.

Raillietina (Raillietina) tunetensis the young spermatid lacks arched membranes. These form only later, at the front of the differentiation zone during spermiogenesis, as in most of the Digenea (Justine, 1991). In a previous article dealing with the ultrastructural study of spermiogenesis and the spermatozoon of the

Cyclophyllidean Thysaniezia ovilla we were able to show that in the cestode spermatozoon the extremity exhibiting the crest-like body or bodies corresponds to the front of the gamete (Ba et al., 1991). In the same way the extremity with crest-like bodies of the R. (R.) tunetensis spermatozoon corresponds to its anterior

Spermiogenesis and spermatozoon

I

II

III

245

extremity and the one without crest-like bodies to its posterior extremity. One or more crest-like bodies have been described on the spermatozoa of 20 cestodes, spread over 17 genera, 8 families and 4 orders (Table 1). In R. serrata, H. nana and Aporina delafondi the crest-like bodies are of the same thickness but of different lengths. On the other hand in M. expansa, M. benedeni and Th. ovilla they are not only of the same thickness but also the same length. R. (R.) tunetensis exhibits two crest-like bodies like the preceding cestodes, but they are of unequal thickness and length. In fact cross sections showing a single crest-like body are about 10 times more frequent than sections showing two crest-like bodies. The cortical microtubules of the spermatozoa of all the Cyclophyllidea are spiralized (Justine, 1991). The angle of spiralization of these microtubules has been evaluated as 50” in S. globipunctata by Ba & Marchand (1992a), 45’ in M. expansa by Swiderski (1968) and Bb & Marchand (1992c), 40” in M. herpestis by B1 & Marchand (in press a), 35” in A. centripunctata by B1 & Marchand (in press b), 25” in R. serrata by Bb & Marchand (1993), 15” in A. delafondi by BP & Marchand (1994) and 13”in H. nana by BB & Marchand (1992b). It is roughly 60” in R. (R.)

IV

of R. (R.) tunetensis

tunetensis.

Granules of proteinaceous material have been described around the nucleus and the axoneme of the spermatozoon of M. expansa by Swiderski (1968), Bb, C.T. unpublished thesis, University of Dakar, 1989, Bd & Marchand (1992c), M. benedeni by Bb, C.T. 1989 (thesis cited above), Ba & Marchand (1992c), Proteocephalus longicollis by Swiderski, Z. & EkluNatey, R.D. (1978. Abstract in Proceedings of the Ninth International

Congress of Electron Microscopy,

Toronto 2: 572-573), Monoecocestus americanus by Mackinnon L Burt (1984), Th. ovilla by Ba et al. (1991) and A. delafondi by Bb & Marchand (1994). In R. (R.) tunetensis, on the other hand, these granules do not exist. They are replaced by intracytoplasmic partitions of electron-dense material associated with a fine

E rl FIG. 22. Attempted reconstruction of the mature spermatozoon of Raillietina (Raillietina) tunetensis in which we

V

distinguish five regions (I-V) from anterior to posterior. To make the diagram clearer, the spiral coil of the cortical microtubules and that of the nucleus have not been shown. Aae = axonemal anterior extremity; AC = apical cone; Ape = axonemal posterior extremity; Ax = axoneme; Cb = crest-like bodies; Cm = cortical microtubules; G = granular electron-dense material; N = nucleus; Sh = sheath of electron-dense peri-axonemal material; W = wall of intracytoplasmic electron-dense material.

246

C. T. BK and B. MARCHAND TABLE ~-VARIATION OF THE NUMBER

Order

Family

Genus

OF CREST-LIKEBODIES

Diphyllobothriidae

DuthiersiaJimbriata

DiphyUidea

Echinobothriidae

Echinobothrium typu.s E. brachysoma E. harfordi

Tetraphyllidea

Phyllobothriidae Nematotaeniidae Hymenolepididae

Cyclophyllidea Anoplocephalidae

1

Reference Justine, 1986 Azzouz-Draoui, 1985 (abstract) Azzouz-Draoui, 1985 (abstract) Azzouz-Draoui, 1985 (abstract) Azzouz-Draoui & Mokhtar-Maamouri,

1986

1 1 1

1

Mokhtar Maamouri & Swiderski, 1975 Mokhtar Maamouri & Swiderski, 1975 Mokhtar Maamouri, 1976 (abstract); 1982 Mahendrasingam et al., 1989

Phyllobothrium gracile Pseudanthobothriwn hanseni

1 1

Mokhtar Maamouri, 1979 Mackinnon & Burt, 1984

1

Mokhtar Maamouri & Azzouz-Draoui, m & Marchand, 1993 Bi & Marchand, lW2b

Nematotaenia chantalae Retinometra serrata Hyrnenolepis nano Aporina delafondi Thysaniezia ovilla Moniezia exponsa Moniezia benedeni Stilesia globipunctata Avitellina eentripunctata

Mathevotaenia Davaineidae

SPERMATOZOON

file benedeni Onchobothriwn uncimtum Acanthobothrium jilicolle jlieolle Trilocularia acanthiaewdgaris

Acanthobothrim Onchobothriidae

CESTODES

Crest-like bodies

and species

Pseudophyllidea

IN THE

herpestis

Raillietina (R) tunetensis

discontinuous sheath of dense peri-axonemal material and a thin discontinuous layer of dense granular submicrotubular material. Moreover an accumulation of electron-dense intracytoplasmic material is observed at the posterior extremity of the spermatozoon. In A. centripunctata we described intracytoplasmic partitions of proteinaceous material, without specifying their origin. In R. (R.) tunetensis however, we think that all the electron-dense intracytoplasmic material comes from the transformation of the electron-dense granule observed in the spermatid cytoplasm at the time of the migration of the nucleus. Moreover, in R. (R.) tunetensis we consider that the dense peri-axonemal material is formed after the migration of the nucleus, since we have never observed this material interposed between the nucleus and the axoneme. For Euzet, Swiderski & Mokhtar-Maamouri (198 l), the cytoplasm of the cestode spermatozoon is of low density. However, in R. serrata as shown by Bi & Marchand (1993) and M. herpestis by BP & Marchand (in press a), it was demonstrated the existence of electron-dense material at the posterior extremity of the gamete. Moreover in H. nana as shown by Bb & Marchand (1992b), regions I and II of the spermatozoon are electron-lucent. Lastly, in A. centripunctata as demonstraed by B5 & Marchand (in

6 12 5 2 2 2

1 1 1

BI & Marchand, in press c BL et al., 1991 B1& Marchand, 1992~ BH& Marchand, 1992~ BL & Marchand, 1992a BI & Marchand, in press b BI & Marchand, in press a

2

Present paper

1990

press b) only the anterior extremity of the apical cone and region I of the gamete exhibit partitions of proteinaceous material delimiting compartments of electron-lucent material. By its partitions of proteinaceous material and its compartments of electron-lucent material the cytoplasm of the R. (R.) tunetensis spermatozoon greatly resembles that of A. centripunctata. It is distinguished from it, nevertheless, in regions I and II by the presence of electron-dense granules forming a periaxonemal layer and a layer subjacent to the cortical microtubules. The nucleus of the spermatozoon of most of the Cyclophyllidea (Swiderski, 1970; Swiderski, Z. 1984. Abstract in Proceedings of the Electron Microscopy Society of Southern Africa 14: 131-132; MokhtarMaamouri & Azzouz-Draoui, 1990; Bt et al., 199 1; BB & Marchand, 1992a, 1993, 1994, in press a,b), Proteocephalidea (Swiderski, Z. & Eklu-Natey, R.D. 1978. Abstract cited above), Diphyllidea (AzzouzDraoui, N. unpublished thesis, University of Tunis, 1985; Azzouz-Draoui & Mokhtar-Maamouri, 1986) and Tetraphyllidea-Phyllobothriidae (Mokhtar-Maamouri, F. unpublished thesis, University of Montpellier II, 1976; Mokhtar-Maamouri, 1979; Mackinnon & Burt, 1984) exhibits a longitudinal groove containing the flagellum. In cross section it therefore usually

Spermiogenesis and spermatozoon appears crescent-shaped. However, the nucleus of the M. herpestis spermatozoon (Bb & Marchand, in press a) is very flattened and may completely envelop the axoneme. In this case it has an annular cross section. In R. (R.) tunetensis the nucelus envelops the axoneme even more completely, coiling round it once or twice. In cross section it is therefore seen as a spiral. To our knowledge such a spiralized nucleus has never been described before in a cestode. REFERENCES AZZOUZ-DRAOUI

N.

& MOKHTAR-MAAMOURI

1986. et du spermatozoi’de de Echinobothrium afine Diesing, 1863 et E.harfordi Mac Vicar, 1976 (Cestoda, Diphyllidea). Bulletin de la Sociitk de Sciences naturelles de Tunisie 18: 920. BA C. T., MARCHAND B. & MATTEI X. 1991. Demonstration of the orientation of the cestode spermatozoon illustrated by the ultrastructural study of spermiogenesis and the spermatozoon of a Cyclophyllidea: Thysaniezia ovilla Rivolta, 1874. Journal of Submicroscopic Cytology and Pathology 23: 605412. BA C. T. & MARCHAND B. 1992a. Ultrastructural particularities of the spermatozoon of Stilesia globipunctata (Cestoda) parasite of the small intestine of sheep and goats in Senegal. Journal of Submicroscopic Cytology and Pathology 24: 29-34. Bi\ C. T. & MARCHAND B. 1992b. Reinvestigation of the ultrastructure of spermiogenesis and the spermatozoon of Hymenolepis nana (Cestoda, Cyclophyllidea) parasite of the small intestine of Rattus rattus. Molecular Reproduction and Development 33: 3945. B.&C. T. & MARCHAND B. 1992~. Ultrastructural study of the spermatozoa of Moniezia expansa Rudolphi, 18 10 and M. benedeni Moniez, 1879 (Cestoda, Cyclophyllidea, Anoplocephalidae). Annales de Parasitologic Humaine et Compa&e 67: 111-115. BA C. T. & MARCHAND B. 1993. Ultrastructure of the Retinometra serrata spermatozoon (Cestoda) intestinal parasite of turtle-doves in Senegal. Journal of Submicroscopic Cytology and Pathology 25: 233-238. BK C. T. & MARCHAND B. in press a. Ultrastructure of spermiogenesis and the spermatozoon of Mathevotaenia herpestis (Cestoda) intestinal parasite of Atelerix albiventris in Senegal. Acta Zoologica. Bii C. T. & MARCHAND B. in press b. Ultrastructure of the spermatozoon of Avitellina centripunctata (Cestoda, Cyclophyllidea), a parasite of the small intestine of cattle in Senegal. Acta Zoologica. B,& C. T. & MARCHAND B. 1994. Ultrastructure of spermiogenesis and the spermatozoon of Aporina delafondi (Cyclophyllidea, Anoplocephalidae), parasite of the intestine of turtle doves in Senegal. International Journal for Parasitology 24: 225-235. EUZET L., SWIDERSKI Z. & MOKHTAR-MAAMOURI F. 1981. Ultrastructure cornparke du spermatozoi’de des Cestodes. Relation avec la phylogentse. Annales de Parasitologic Humaine et Comparie 56: 247-259.

Ultrastructure cornparke de la spermiogenbe

F.

of R. (R.) tunetensis

247

FEATHERSTON D. W. 1971. Taenia hydatigena: III. Light and electron microscope study of spermatogenesis. Zeitschrift fir Parasitenkunde 37: 148-168. JUSTINE J. L. 1991. Phylogeny of parasitic Platyhelminthes: a critical study of synapomorphies proposed on the basis of the ultrastructure of spermiogenesis and spermatozoa. Canadian Journal of Zoology 69: 1421-1440. KELSO G. H., UBELAKKER J. E. & ALLISON V. F. 1977. The fine structure of spermatogenesis in Hymenolepis diminuta (Cestoda) with a description of the mature spermatozoon. Zeitschrift fiir Parasitenkunde 54. 175-187. LUMSDEN R. D. 1965. Microtubules in the peripheral cytoplasm ofcestode spermatozoa. Journal of Parasitology 51: 929-931. MACKINNON B. M. &BURT M. D. B. 1984. The comparative ultrastructure of spermatozoa from Bothrimonus stirionis Duv. 1842 (Pseudophyllidea), Pseudanthobothrium hanseni Baer, 1956 (Tetraphyllidea) and Monoecocestus umericanus Stiles, 1895 (Cyclophyllidea). Canadian Journal of Zoology 62: 1059-1066. MACKINNON B. M. & BURT M. D. B. 1985. Ultrastructure of spermatogenesis and the mature spermatozoon of Haplobothrium globuliforme Cooper, 1914 (Cestoda: Haplobothrioidea). Canadian Journal of Zoology 63: 1478&1487. MAHENDRASINGAM S., FAIRWEATHER I. & HALTON D. W. 1989. Spermatogenesis and the fine structure of the mature spermatozoon in the free proglottis of Trilocularia acanthiaevulgaris (Cestoda, Tetraphyllidea). Parasitology Research 75: 287-298. MOKHTAR-MAAMOURI F. & SWIDERSKI Z. 1975. Etude en microscopic klectronique de la spermatogentse de deux cestodes Acanthobothrium jillicole benedenii Loennberg, 1889et Onchobothriumuncinatum(Rud., 1819)(Tetraphyllidea, Onchobothriidae). Zeitschrlytfiir Parasitenkunde 47: 269-28 1. MOKHTAR-MAAMOURI F. 1979. Etude en microscopic Clectronique de la spermiogenPse et du spermatozoi’de de Phyllobothrium gracile Weld, 1955 (Cestoda, Tetraphyllidea, Phyllobothriidae). Zeitschrif fiir Parasitenkunde 59: 245-258. MOKHTAR-MAAMOURI F. 1982. Etude ultrastructurale de la spermiogentse de Acanthobothrium filicolle var. jillicole Zschokke, 1888 (Cestoda, Tetraphyllidea, Onchobothriidae). Annales de Parasitologic Humaine et Compar6e 5: 42942. MOKHTAR-MAAMOURI F. & AZZOUZ-DRAOUI N. 1990. Etude de la spermiogentse et de l’ultrastructure du spermatozo’ide de Nematotaenia chantalae Dollfus, 1957 (Cestoda, Cyclophyllidea, Nematotaeniidae). Annales de Parasitologic Humaine et Comparie 65: 221-228. MORSE~H D. J. 1969. Sperm tail fine structure of Echinococcus granulosus and Dicrocoelium dendriticum. Experimental Parasitology 24: 47-53. ROBINSON J. M. & BOGITSCH B. J. 1978. A morphological and cytochemical study of sperm development in Hymenolepis diminuta. Zeitschrif ftir Parasitenkunde 56: 8 l-92. ROSARIO B. 1964. An electron microscope study of spermatogenesis in Cestodes. Journal of Ultrastructure Research 11: 412427.

C. T. BA and B. MARCHAND

248

RYBICKA K. 1962. La spermatogenese dun Cestode Cyclophyllidea, Dipylidium caninum. Bulletin de la Societd Zoologique

de France 87: 225-228.

SCHMIDT G. D. 1986. CRC Handbook of Tapeworm identification. CRC Press, Boca Raton, FL. SUNC. N. 1972. The fine structure of sperm tail of cotton-rat tapeworm, Hymenolepisdiminuta. Cytobiology6: 382-386. SWIDERSKI Z. 1968. The fine structure of the spermatozoon of sheep tapeworm, Moniezia expansa (Rud., 1810) Cyclophyllidea, Anoplocephalidae. Zoologica Poloniae 18:4755 486.

SWIDERSKIZ. 1970. An electron microscrope study of spermatogenesis in Cyclophyllidean Cestodes with emphasis on the comparison of fine structure of mature spermatozoa. Journal of Parasitology 56: 337-338. SWIDERSKI Z. & MOKHTAR-MAAMOURI F. 1980. Etude de la spermatogenbse de Bothriocephalus clavibothrium Ariola, 1899 (Cestoda, Pseudophyllidea). Archives de I’lnstitut Pasteur de Tunis 57: 323-347.

VASSILIADES G. 1980. Helminthes parasites d’oiseaux du Senegal. Bulletin de I’lnstitut Fondamental d’Afrique Noire, s&ie A 42: 122-134.