An Electron Microscope Study of the Trichomonas criceti

Transcription

1 320 Cytologia 26 An Electron Microscope Study of the Trichomonas criceti J. Chakraborty, N. N. Das Gupta and N. N. Ray Received January 17, 1961 Biophysics Division, Saha Institute of Nuclear Physics, Calcutta-9, and School of Tropical Medicine, Calcutta-12, India Introduction Trichomonad flagellates were studied under the optical microscopy by Kofoid and Swezy (1915), Wenrich (1921 and 1944), Sammuels (1941.and 1957), Buttrey (1954) and Ludvik (1954). Later on Anderson (1955a, b) and Anderson and Beams (1959) studied the ultrastructural organisation of these flagellates with the help of electron microscope and ultrathin sectioning tech niques. Inoki et al (1959) studied the ultrastructure of T. vaginalis. The present paper deals with some new findings in the ultrastructural organisation of Trichomonas criceti (Ray et al). Material and methods The organisms were obtained from the caecum of the hamster. They were fixed in 1% OsO4 solution buffered at ph 7.4 for 30 minutes. After fixation, dehydration, infiltration, embedding and sectioning were done as usual. The sections were examined under a Siemens' Elmiskop I at 60 K. V. Observations Anterior flagella: The flagellum is found to consist of a number of fibrils running longitudinally along its length, surrounded by a thin flagellar sheath. In transverse section of the flagella (Fig. 2) one central fibril is seen surrounded by nine peripheral fibrils, the average thickness of each of which is about 400A. In the longitudinal section through the flagella a maximum number of 3 to 4 fibrils can be very clearly counted (Figs. 1, 3 and 4). The flagellar sheath is thin, continuous and appears to be 230A thick. Basal apparatus of the anterior flagella: The fibrillar bundle of the flagella extends ( )ƒÊ into the body of the protozoon (Fig. 1). There is a double layered membrane, surrounding the base of the flagella, a por tion of which is clearly visible in Fig. 1. The outer layer of this membrane is found to be continuous but the inner one is possibly fibrillar as in the oblique section it appears as a dotted line. The total thickness of the two layers together is about 900A. At the base of the flagellum there is a double

2 1961 An Electron Microscope Study of the Trichomonas criceti 321 walled filamentous structure about 1.4ƒÊ long (Figs. 1 and 3). The costa is attached to this structure (Fig. 3). Parabasal body: The parabasal body of these organisms con sists of a number of thick walled, long la mellar structures, ar ranged in a parallel array (Figs. 5, 6 and 7). The membranes of these lamellae are con stricted in some places. The distance between two membranes is about 150A and the thickness of each of the membranes is about (250 to 300) A. The parabasal filament origi nates from the blepha roplastic region and is attached to the parabasal body (Fig. 6). Recurrent flagel la, "accessory fila ment" and undulating membrane: The re current flagella have an internal structure similar to that of the anterior one (Fig. 1). The undulating mem brane is composed of a sheet-like structure. Between the recurrent Figs , oblique section of T. criceti showing the anterior flagella (FA), basal body (B), membrane of the kinetosomal vacuole (KM), recurrent flagellum (FR), undulating membrane (UM), sheet of the undulating membrane (UMS), accessory filament (AF) and mitochondria (M). ~6,600. 2, transverse section of the flagellum (F) showing the peripheral (FFP) and central fibrils (FFC) and the flagellar sheath (FS). ~32,700, 3, section passing through the basal apparatus of the flagellum showing the fibrils of the flagellum (FF), filamentous structure at the base of the flagellum (Fl) and a portion of the costa (CO). ~13,600. 4, longitudinal section of the anterior flagella (FA), showing the fibrils (FF) and the sub-fibrils (FFS'). ~ 25,000. flagella and the sheet of the undulating membrane, there is a granular structure which is termed as the accessory filament. In Fig. 5, the components of the undulating membrane are clearly visible. The undulating sheet, recurrent flagellum and the accessory filament are surrounded brane (Figs. 1 and 5). by a 120A thick mem Axostyle and costa: Axostyle is a long, thick, rod-like structure, trav-

3 322 J. Chakraborty, N. N. Das Gupta and H. N. Ray Cytologia 26 ersing throughout the entire length of the body of the protozoon (Fig. 9B). It has a thick double walled limiting membrane (Fig. 9B). There are small fibrillar connections between these two walls (Fig. 10). The thickness of this axostylar mem brane brane is about 600A. Inside the axostyle there are a number of rounded, filamentous or granular structures (Fig. 10). The costa is also a long curved structure (Fig. 11), originating from the blepharo plastic region of the flagellum (Fig. 3). It is composed of a number of double walled disk-like struc tures tures ( `320A in thickness) embedded Figs , section passing through the sheet of the undulat ing membrane (USM). The recurrent flagellum (FR), accessory filament (AF) and the fine double walled membrane (UM) surrounding them are clearly visible. The parabasal body (PB) is also present. ~20,800. 6, section showing the lamella of the parabasal body (PB) and the parabasal filament (PF) ~ 26,700. 7, section passing through part of parabasal body (PB). The parabasal filament is absent in this figure. ~32,700. 8, section showing flagellar extension inside the body of the parasite (F). ~16,000. in a homogeneous matrix (Fig. 11). They are separated from each other by a distance of 140A. Granular struc tures: Paracostal gran ules, para-axostylar granules and chromatic granules are found scattered all over the body of this protozoon (Figs. 11, 10 and 1). Besides these types of granules, there are also other granules, the exact nature of which is not yet known (Fig. 12). These granules are surrounded by a double walled 200A thick membrane. The limiting membrane is not smooth and is constricted or elevated at some places. A rounded closely packed dense network-like struc ture is seen inside these granules. Nucleus: The nucleus is a prominent elongated body, situated near-the anterior end. It is surrounded by a distinct double-walled membrane about

4 1961 An Electron Microscope Study of the Trich omonas criceti A thick. There is a small gap between the outer and inner nucl ear memb ranes (Fig. 13). Both the outer as well as the inner nucl ear membranes are interrupted by small pores (Figs. 13 and 14). The nucleus is filled up with the granular nucleo plasm (Fig. 14). Some times a few denser bodies are visible in the nucleoplasm (Fig. 10). They may be the sec tions passing through the chromosomes. Mitochondria: Besides the paracostal para-axostylar and chromatic granules some less dense rounded or oval bodies are scattered all over the body at random (Fig. 1), which are surrounded by a 200A thick smooth mem brane (Fig. 9B). They are the sections of mitochondria; some times very faint "mic rovilli" are also visible inside them (Fig. 9B). Discussion The fine structure of the flagella of Trichomonas criceti shows the same Figs A, section passing through the median and lateral axostyle (MAX and LAX) and nucleus (N). ~5,000. 9B, oblique section of axostyle (AX) showing the rounded (r) and fi lamentous (f) structure inside it. The mitochondria (M) with faint microvilli (MC) are also visible. ~26, , section showing the double walled membrane of the axostyle (AXM) and the fine fibrillar connections (AXF) between these two membranes. The para-axostylar granules (PAG) and the sec tion of chromosomes (CH) are also clearly visible. ~16, , section of costa (CO), showing the double walled disk-like structures (DK) and the paracostal granules (PCG). ~25,000. pattern, as observed in the flagella and cilia of other, protozoan cells. Chang (1956), Inoki et al (1957), Pyne (1958), Pyne and Chakraborty (1958) found one central fibril surrounded by nine peripheral fibrils in L. donovani. In the present investigation also one central and nine peripheral fibrils are cearly visible, thus agreeing with the observations of Anderson and Beams (1959) and Inoki et al (1959) in T. muris The central as well as the peripheral fibrils and T. vaginalis. extend into the body forming

5 324 J. Chakraborty, N. N. Das Gupta and H. N. Ray Cytologia 26 the basal body. No granular structure, which may be called as the basal granule was found in this species. A double-walled filamentous structure is visible at the base of the flagellum (Fig. 3) the exact nature of which is not yet un derstood. The pelli cular layer invaginates inside the body of the parasite near the base of the flagellum, form ing the membrane of a vacuole. A similar structure was also found by Pyne and Chakraborty in Lei shmania donovani (1958). The double-walled lamellae and thick walled vesicles in the Figs , section passing through the granules (G) of unknown nature. These granules are surrounded by a double walled limiting membrane (LM). Closely packed dense net work like structures (DPN) are visible inside these granules. ~ 53,300, 13, section of a portion of nucleus (N) showing the double walled nuclear membrane (NM) and the pores (NMP). parabasal body found in this organism, re semble those reported by Anderson and Beams in T. muris (1959). The parabasal filament also shows the same internal structure. ~ 53,300. The similarity in structure between the recurrent and the anterior flagella and the granular nature of the accessory filament found in this work also agree with the observations of Anderson and Beams in T. muris (1959). However, the internal structure of the undulating membrane consists of a thick sheet instead of series of parallel lamellae (Anderson 1955a). Anderson and Beams (1959) observed a "fibrous sheet like component" embeded in a granular matrix which was not observed by the present authors. The costa is an antero-posteriorly curved body, composed of a series of disks embedded in a matrix (Anderson 1955a and Anderson 1955b). The ultrastructure of axostyle has been described by Anderson (1955a) and Anderson and Beams (1959). Anderson (1955a) observed that it was limited by a double-walled "Corrugated" membrane. Anderson and Beams (1959) found

6 1961 An Electron Microscope Study of the Trichomonas criceti 325 that the surface of this organelle was composed of fine oblique filaments. Inoki et al (1959) observed small granules and stripes inside the axostyle. In the present study the double-walled mem brane with small fila ments between them have clearly been identified. Various types of granules were reported by Anderson (1955a) in T. muris and Inoki et al (1955) in T. vaginalis. The para costal bodies, as observed by Anderson and Beams (1959) in T. muris, composed of a granular or vesicular structure sur rounded by a double walled membrane. An derson (1955a) reported these granules to be vacuolated and sur rounded rounded by a 200A thick membrane. The internal structures of Fig. 14. Section passing tmougn the nueleus (N), snowing the prominent double walled nuclear membrane (NM), the pores (NMP) of the nuclear membrane are also visible. ~40,000. paracostal and para-axostylar granules observed in the present investigation are slightly different, which are composed of homogeneous matrix. The limiting membranes are not clearly visible. Some granules, scattered all over the body of this protozoon show the evidence of a compact network sur rounded by a double-walled limiting membrane. The nucleus is surrounded by a double-walled porous membrane. The porous nature of the nuclear membranes were reported by several investigators (Bairati and Lehmann 1952, Harris and James 1952, Pappas 1956, Greider et al 1956 and 1958) in Amoeba proteus. Amongst the flagellates the porous nature of the inner nuclear membrane was observed by Chakraborty and Das Gupta (1960). Anderson and Beams (1959) and Inoki et at (1959) ob served a double-walled nuclear membrane interrupted by pores in T. muris and T. vaginalis. Some less dense bodies limited by single walled membrane have been noticed. Anderson and Beams (1959) observed the same type of mito-

7 326 J. Chakraborty, N. N. Das Gupta and H. N. Ray Cytologia 26 chondria in T. muris but Inoki et al (1959) reported that there was no mitochondria in T. vaginalis. Acknowledgement The authors are indebted to the Ministry of Scientific Research and Cultural Affairs, Government of India for research grants and to Mr. M. L. De for help in the electron micrographs. References Anderson, E. 1955a. The electron microscopy of Trichomonas muris. J. Protozool. 2: b. The electron microscopy of Trichomonas muris. J. Protozool. 2, suppl.: and Beams, H. W The cytology of Trichomonas as revealed by the electron microscope. J. Morphol. 104: Bairati, A, and Lehmann, F. E Ober die submikroskopische Struktur der Kern membran bei Amoeba proteus. Experientia 8: 60. Buttrey, B. W Morphological variations in Trichomonas augusta (Alexeieff) from amphibia. J. Morph. 94: Chakraborty, J. and Das Gupta, N. N Ultrastructure of the pellicle and the nucleus of Leishmania donovani. Fourth Int. Conf. on Elec. Micros. (Berlin), Band 11: Chang, P. C. H The ultrastructure of Leishmania donovani. J. Parasitol. 42: Greider, M. H., Kostir, W. J. and Frajola, W. J Electron microscopy of the nuclear membrane of Amoeba proteus. J. Biophysic. and Biochem. Cytol. 2 suppl , - and Electron microscopy of Amoeba proteus. J. Protozool. 5: Harris, P- and James, T. W Electron microscope study of the nuclear membrane of Amoeba proteus in thin sections. Experientia 8: 384. Inoki, S., Nakanishi, K. and Nakabayashi, T Observations on Trichomonas vaginalis by electron microscopy. Biken's Jour. 2 (I): , -, - and Ohno, M Fine structure of the flagellum of Leishmania donovani revealed by electron microscope. Med. J. Osaka Univ. 7: Kofoid, C. A. and Swezy, O Mitosis and multiple fission in trichomonad flagellates. Proc. Amer. Acad. Arts. Sci. 51: Ludvik, J Studium bunecne morfologie Trichomonas foetus (Riedmuller) elektronoym mikroskopen. Acta Soc. Zool. Bohemoslovenicae 18: Pappas, G. D The fine structure of nuclear envelope of Amoeba proteus. J. Biophysic. and Biochem. Cytol. 2: suppl Pyne, C. K Electron microscopic investigations on the leptomonad form of Leishmania donovani. Exptl. Cell Res. 14: and Chakraborty, J Electron microscopic studies on the basal apparatus of the flagellum in the protozoon, Leishmania donovani. J. Protozool. 5: Ray, H. N. and Sen Gupta, P. C. On the morphology of Trichomonas criceti n. sp. found in the golden hamster. In press. Samuels, R The morphology and division of Trichomonas augusta (Alexeiff). Trans. Am. Micro. Soc. 60: Studies of Trichomonas batrachorum I. The tropic organism. J. Protozool. 4: Wenrich, D. H The structure and division of Trichomonas muris Hartman. J. Morphol. 36: Morphology of the intestinal trichomonad flagellates in man and of similar forms in monkeys, cats, dogs and rats. J. Morphol. 74: