, Volume 73, Issue 5, pp 467–476 | Cite as

Light microscopy observations on the encystation and excystation processes of the ciliate Phacodinium metchnikoffi (Ciliophora, Phacodiniidae), including additional information on its resting cysts structure

  • Simona Benčaťová
  • Eva Tirjaková
Original Article


The scope of our study presents a light microscopy study on the encystation, excystation and morphology of the resting cysts of the spirotrich ciliate, Phacodinium metchnikoffi. During the encystation process, the trophic cell changes in shape, size and volume, the horseshoe-shaped macronuclear nodule transforms into a compact rounded mass, the ciliature is resorbed and the cyst wall is formed. A characteristic accumulation of dark substances in the cell cytoplasm was observed. The most significant feature is the surface. Ornamentation in the form of protuberances in regular rows is located on the entire surface of the cysts. We also focused on the excystation process for the first time and uncovered several specifics of P. metchnikoffi excystation. The excystation is characterised by the formation of the excystation vacuole. An escape apparatus is also present. The coexistence of the excystation vacuole and apparatus during the excystation process is an unusual type of escaping and has not yet been described. The results suggest that not only the resting cysts surface, but also the excystation and encystation processes are much more varied than literary data indicate.


Escape apparatus Excystation vacuole Surface morphology Protuberances Resting cyst 



This work was supported by the Slovak Scientific Grant Agency (Project No. 1/0114/16 and Project No. 1/0041/17). We would also like to thank RNDr. Viktória Čabanová for collecting the moss samples and Mike Sabo for English correction.

Compliance with ethical standards

Ethical approval

This article does not contain any studies with animals performed by any of the authors.

Conflict of interest

The authors declare that they have no conflict of interest.


  1. Akematsu T, Matsuoka T (2007) Excystment-inducing factors in the ciliated protozoan Colpoda cucullus: hydrophobic peptides are involved in excystment induction. Acta Protozool 46:9–14Google Scholar
  2. Barrero SS (2010) Characterización filogenética de Phacodinium metchnikoffi: Análisis comparativo de datos morfológicos, morfogenéticos y moleculares. Universidad Comlutense de MadridGoogle Scholar
  3. Beers CD (1945) The excystation process in the ciliate Didinium nasutum. J Elisha Mitchell Sci Soc 61:264–275Google Scholar
  4. Beers CD (1948) Excystation in the ciliate Bursaria truncatella. Biol Bull 94:86–98. CrossRefPubMedGoogle Scholar
  5. Beers CD (1966) The excystation process in the ciliate Nassula ornata Ehrbg. J Protozool 13:79–83. CrossRefPubMedGoogle Scholar
  6. Benčaťová S, Tirjaková E (2017a) Prvonález druhu Bresslauides terricola (Foissner, 1987) Foissner, 1993 (Ciliophora, Colpodea) na Slovensku – cystické štádiá, en- a excystácia. Folia Faun Slovaca 22:31–40Google Scholar
  7. Benčaťová S, Tirjaková E (2017b) A study on resting cysts of an oxytrichid soil ciliate, Rigidohymena quadrinucleata (Dragesco and Njine, 1971) Berger, 2011 (Ciliophora, Hypotrichia), including notes on its encystation and excystation process. Acta Protozool 56:77–91Google Scholar
  8. Benčaťová S, Tirjaková E, Vďačný P (2016) Resting cysts of Parentocirrus hortualis Voss, 1997 (Ciliophora, Hypotrichia), with preliminary notes on encystation and various types of excystation. Eur J Protistol 43:295–314. Google Scholar
  9. Berger H (1999) Monograph of the Oxytrichidae (Ciliophora, Hypotrichia). Monogr Biol 78:1–1080. Google Scholar
  10. Calvo P, Torres A, Navas P, Perez-Silva J (1983) Complex carbohydrates in the cyst wall of Histriculus similis. J Gen Microbiol 129:829–832. Google Scholar
  11. Cavaleiro J, Fernandes NM, da Silva-Neto ID, Soares CAG (2017) Resting cysts of the pigmented ciliate Blepharisma sinuosum Sawaya, 1940 (Ciliophora: Heterotrichea). J Eukarytic Microbiol.
  12. Certes A (1891) Note sur deux infusoires nouveaux des environs de Paris. Mém Soc Zool France 4:536–541Google Scholar
  13. da Silva-Neto ID (1993) Structural and ultrastructural observations of the ciliate Phacodinium metchnikoffi certes, 1891 (Heterotrichea, Phacodiniida). Eur J Protistol 29:209–218CrossRefPubMedGoogle Scholar
  14. Didier P, Dragesco J (1979a) Organisation ultrastructurale du cortex de Phacodinium metchnikoffi (cilié hétérotriche). Protist 15:33–42Google Scholar
  15. Didier P, Dragesco J (1979b) Organisation ultrastructurale du cortex des vacuoles digestives de Phacodinium metchnikoffi (cilié hétérotriche). Trans Am Microsc Soc 98:385–392. CrossRefGoogle Scholar
  16. Dragesco J (1970) Ciliés libres du Cameroun. Num Hors-Série Ann Fac Sci Yaoundé:1–141Google Scholar
  17. Fernández-Galiano D, Calvo P (1992) Redescription of Phacodinium metchnikoffi (Ciliophora, Hypotrichida): general morphology and taxonomic position. J Protozool 39:443–448. CrossRefPubMedGoogle Scholar
  18. Foissner W (1993) Colpodea (Ciliophora). PRO 4:1–798Google Scholar
  19. Foissner W (2009) The stunning, glass-covered resting cyst of Maryna umbrellata (Ciliophora, Colpodea). Acta Protozool 48:223–242PubMedPubMedCentralGoogle Scholar
  20. Foissner I, Foissner W (1987) The fine structure of the resting cysts of Kahliella simplex (Ciliata, Hypotrichida). Zool Anz 218:65–74Google Scholar
  21. Foissner W, Stoeck T (2009) Morphological and molecular characterization of a new protist family Sandmanniellidae n. Fam. (Ciliophora, Colpodea), with description of Sandmaniella terricola n. G., n. Sp. from the Chobe floodplain in Botswana. J Eukaryot Microbiol 56:472–483CrossRefPubMedPubMedCentralGoogle Scholar
  22. Foissner W, Müller H, Agatha S (2007) A comparative fine structural and phylogenetic analysis of resting cysts in oligotrich and hypotrich Spirotrichea (Ciliophora). Eur J Protistol 43:295–314. CrossRefPubMedPubMedCentralGoogle Scholar
  23. Funadani R, Suetomo Y, Matsuoka T (2013) Emergence of the terrestrial ciliate Colpoda cucullus from a resting cyst: rupture of the cyst wall by active expansion of an excystation vacuole. Microbes Environ 28:149–152. CrossRefPubMedGoogle Scholar
  24. Funadani R, Sogame Y, Kojima K, Takeshita T, Yamamota K, Tsujizono T, Suizu F, Miyata S, Yagyu KI, Suzuki T, Arikawa M, Matsuoka T (2016) Morphogenetic and molecular analyses of cyst wall components in the ciliated protozoan Colpoda cucullus Nag-1. FEMS microbial Lett 363: fnw203.
  25. Grecco N, Bussers JC (1990) Ultrastructural localization of chitin in the cystic wall of Euplotes muscicola Kahl (Ciliata, Hypotrichidia). Eur J Protistol 26:75–80. CrossRefGoogle Scholar
  26. Grimes GW, Hammersmith RL (1980) Analysis of the effects of encystment and excystment on incomplete doublets of Oxytricha fallax. J Embryol Exp Morpholog 59:19–26Google Scholar
  27. Gutiérrez JC, Callejas S, Borniquel S, Benítez L, Martín-González A (2001) Ciliate cryptobiosis: a microbial strategy against an eviromental starvation. Int Microbiol 4:151–157. PubMedGoogle Scholar
  28. Gutiérrez JC, Diáz S, Ortega R, Martín-González A (2003) Ciliate resting cyst walls: a comparative review. Recent Res Dev Microbiol 7:361–379Google Scholar
  29. Kahl A (1932) Urtiere oder Protozoa I: Wimpertiere oder Ciliata (Infusoria). In: Dahl, F. (de.), Die Tierwelt Deutschlands, G. Fisher, JenaGoogle Scholar
  30. Kim Y, Taniguchi A (1995) Excystation of the oligotrich ciliate Strombidium conicum. Aquat Microb Ecol 9:149–156. CrossRefGoogle Scholar
  31. Klionsky DJ, Emr SD (2000) Cell biology - autophagy as a regulated pathway of cellular degradation. Science 290:1717–1721CrossRefPubMedPubMedCentralGoogle Scholar
  32. Levy MR, Elliott AM (1968) Biochemical and ultrastructural changes in Tetrahymena pyriformis during starvation. J Protozool 15:208–222. CrossRefPubMedGoogle Scholar
  33. Li Q, Sun Q, Fan X, Wu N, Ni B, Gu F (2017) The differentiation of cellular structure during encystment in the soil hypotrichous ciliate Australocirrus cf. australis (Protista, Ciliophora). Anim Cells Syst 21:45–52. CrossRefGoogle Scholar
  34. Liu Z, Yi-Song L, Jun-Gang L, Fu-Kang G (2009) Some ultrastructural observations of the vegetative, resting and excysting ciliate, Urostyla grandis (Urostylidae, Hypotrichida). Biol Res 42:395–401PubMedGoogle Scholar
  35. Lynn DH (2008) The ciliated protoza: characterization, classification, and guide to the literature. Springer, CanadaGoogle Scholar
  36. Martín-González A, Benítez A, Gutiérrez JC (1992) Ultrastructural analysis of resting cysts and encystment in Colpoda inflata. 2. Encystment process and a review of ciliate resting cyst classification. Cytobios 72:93–106Google Scholar
  37. Matsusaka T (1979) Effect of cycloheximide on the encystment and ultrastructure of the ciliate, Histriculus. J Protozool 26:619–625. CrossRefGoogle Scholar
  38. Montagnes DJS, Lowe CD, Poulton A, Jonsson P (2002) Redescription of Strombidium oculatum Gruber 1884 (Ciliophora, Oligotrichia). J Eukaryot Microbiol 49:329–337. CrossRefPubMedGoogle Scholar
  39. Müller H (2007) Live observation of excystation in the spirotrich ciliate Meseres corlissi. Eur J Protistol 43:95–100. CrossRefPubMedGoogle Scholar
  40. Penard E (1922) Etudes sur les Infusoires d’eau douce. Georg et Cie, Genève.
  41. Prowazek S (1899-1903) Protozoenstudien I.III. Zoologischen Instituten der Universität Wien, pp 11-14Google Scholar
  42. Rawlinson NG, Gates MA (1985) The excystment process in the ciliate Euplotes muscicola: an integrated light and scanning electron microscopic study. J Protozool 32:729–735. CrossRefGoogle Scholar
  43. Reid PC, John AWG (1983) Resting cysts in the ciliate class Polyhymenophorea: phylogenetic implications. J Protozool 30:710–713. CrossRefGoogle Scholar
  44. Repak AJ (1968) Encystment and excystation of the heterotrichous ciliate Blepharisma stoltei Isquith. J Protozool 15:407–412. CrossRefGoogle Scholar
  45. Roque M (1970) Observations Sur Phacodinium metchnikoffi certes, 1891. Ann Stat Biol Besse-en-Chandesse 5:297–302Google Scholar
  46. Shin MK, Hwang UW, Kim W, Wright ADG, Krawczyk C, Lynn DH (2000) Phylogenetic position of the ciliates Phacodinium (order Phacodiniida) and Protocruzia (subclass Protocruziidia) and systematics of the spirotrich ciliates examined by small subunit ribosomal RNA gene sequences. Eur J Protistol 36:293–302. CrossRefGoogle Scholar
  47. Tsutsumi S, Watoh T, Kumamoto K, Kotsuki H, Matsuoka T (2004) Effects of porphyrins on encystment and excystment in ciliated protozoan Colpoda sp. Jpn J Protozool 37:119–126Google Scholar
  48. Vďačný P, Foissner W (2012) Monograph of the dileptids (Protista, Ciliophora, Rhynchostomatia). Denisia 31:1–529Google Scholar
  49. Verni F, Rosati G (2011) Resting cysts: A survival strategy in Protozoa Ciliophora. Ital. J. Zool. 78: 134–145.
  50. Walker GK, Maugel TK, Goode D (1975) Some ultrastructural observations on encystment in Stylonychia mytilus (Ciliophora: Hypotrichida). Trans Am Microsc Soc 94:147–154. CrossRefGoogle Scholar

Copyright information

© Institute of Zoology, Slovak Academy of Sciences 2018

Authors and Affiliations

  1. 1.Department of Zoology, Faculty of Natural SciencesComenius University in BratislavaBratislavaSlovak Republic

Personalised recommendations