Histological examination of the chaetognathan morphological structure in the region of a supposed trunk-tail septum

A.P. Kassatkina & M.V. Stolyarova

Abstract. A histological examination was conducted based on sections done in series in transverse and longitudinal directions of Aidanosagitta macilenta (Sagittidae, Chaetognatha) in a region which includes the anterior parts of the testes and the posterior part of the ovaries. We found that, in mature individuals (the 4th stage of maturation), the anterior parts of the testes are located in front of the posterior part of the ovaries. The anterior parts of the testes have a ventral position adjoining the ventral muscular bands. The ovaries are located more dorsally than the testes at the level of lateral fi elds. A transverse trunk-tail septum between testes and ovaries was not revealed. These data support an idea that a structure which was earlier treated as a tail-trunk septum is actually the anterior edges of the testes. Both longitudinal coelomic cavities continue into the tail region without any transverse septa. The paired tail cavities as can be seen from their composition and functions represent the testes consisting of a peripheral compact portion with undifferentiated germ cells and a space where the maturation of cells occurs. The tail is distinguished anatomically as a post-anal portion of the body but it is not a true segment as it is not separated from a trunk part of the body by the trunk-tail septum. The body of Chaetognatha consists of two true parts (segments). A mesenterial septum divides the body longitudinally-symmetrically from a trunk-head septum down only to the caudal end of the gut. In the tail region there is a medial septum formed by the medial walls of testes. Gonads in both females and males do not have any duct connecting them with a gut cavity. The ovaries and the testes are covered by a coelomic lining and a duct between the ovaries and the testes is absent.

Zoosystematica Rossica, 2008, 17(2): 61-70  ▪  Published in print 30 December 2008


https://doi.org/10.31610/zsr/2008.17.2.61  ▪  Open full article  

References

Beauchamp, P. 1960. Chaetognatha. In: Grassé, M. P.-P. (Ed.) Traité de Zoologie. 5(2): 1500-1520. Masson et C ie éditeurs, Paris.

Beklemishev, V.N. 1964. Basis of the invertebrate comparative anatomy. V.1: 445 p.Moscow. “Nauka”. (In Russian).

Berezinskaya, T.L. & Malakhov, V.V. 1993. Ultrastructure of the trunk and caudal coeloms in Serratosagitta pseudoserratodentata (Chaetognatha). Zoologicheskiy Zhurnal, 72: 36-47. (In Russian with English summary).

Büchner, P. 1910. Die Schicksale des Keimplasmas der Sagitten in Reifung. Befruchtung, Keimbahn, Ovogenese und Spermatogenese. Anat. Anz. Iena, 1(17-22): 233-288.

Bütschli, O. 1873. Zur Entwicklung der Sagitta. Z. wiss. Zool., 23: 409-413.

Darwin, C. 1844. Observations on the structure and propagation of the genus Sagitta. Ann. Nat. Hist., 13(1): 360. https://doi.org/10.1080/03745484409442559

Davidov, K.N. 1914. Kurs embriologii bespozvonochnykh [Embryology of invertenrates]. Sotrudnik”, Saint-Petersburg – Kiev. 502 p. (In Russian).

Dogel, V.A. 1975. Zoologiya bespozvonochnykh. [Zoology of invertebrates]. Vysshaya shkola, Moscow. 559 p. (In Russian).

Doncaster, L. 1902. On the development of Sagitta with notes on the anatomy of the adult. Quart. J. Microsc. Sci., 46: 1-267.

Elpat’evskiy, V.S. [Elpatiewsky, W.S.] 1910. Die Entwiklungsgeschichte der Genitalprodukte bei Sagitta. I. Die Entwiklung der Eier. Biologicheskiy Zhurnal, 1(4): 1-10.

Elpat’evskiy, V.S. 1913. Origin of the ovum and embryological development of Sagitta. Part 1: Origin of the ovum. Izvestiya Obschestva Lubiteley Estestvoznanya, Antropology, Etnography, 126(1): 1-69. (In Russian).

Elpatiewsky, V.S. 1914. Origin of the ovum and embryological development of Sagitta. Part 2: Embryological development. Izvestye Obschestva Lubiteley Estestvoznanya, Antropology, Etnography, 126(2): 1-48.(In Russian).

Filatova, Z.A. 1951. Class Chaetognatha. In: Zenkevich, L.A. (Ed.) Rukovodstvo po zoology, 3(2): 592-608. Sovetskaya nauka, Moscow. (In Russian).

Hertwig, G.O. 1880. Die Chaetognathen, ihre Anatomie, Systematik und Entwicklungsgeschichte. Vol. 7. Jena. 330 p. https://doi.org/10.5962/bhl.title.15245

Hyman, L.H. 1959. Phylum Chaetognatha. In: The Invertebrates, 5: 1-71.McGraw-Hill, New York.

Ivanov, P.P. 1937. Obshchayai i sravnitel’naya embryologiya [General and comparative embryology].Biomedgiz, Moscow-Leningrad. 809 p. (In Russian).

Ivanova-Kazas, O.M. 1977. Sravnitel’naya embriologiya bespozvonochnykh zhivotnykh: trokhofornyye, shchupal’tsevyye, shchetinkochelyustnyye, pogonofory [Comparative embryology of invertebrates: Trochozoa, Tentaculata, Chaetognatha, Pogonophora]. Nauka, Moscow.312 p. (In Russian).

Kassatkina, A.P. 1982. Shchetinkochelyustnyye morye SSSR I sopredel’nykh vod [Chaetognaths of the seas of USSR and adjacent waters]. Nauka, Leningrad. 136 p. (In Russian).

Kotori, M. 1979. The biology of Chaetognatha in the Bering Sea and the northwestern North Pacific Ocean, with emphasis on Sagitta elegans Verrill (review). Bulletin of Plankton Society of Japan, 26: 25-39.

Kowalevsky, A.O. 1871. Embriologische Studien an Wurmen und Artropoden. Entwicklungsgeschichte der Sagitta. Mémoires de l’Academie Imperiale des Sciences de St. Petersbourg, 16(7[12]): 1-70.

Kühl, W. 1938. Chaetognatha. In: Bronns Klassen und Ordnungen des Tierreiches, 4(4[2]). Akad. Verl.-Ges., Leipzig. 226 p.

Shinn, G.L. 1997. Chaetognatha. In:Harrison, F.W. & Ruppert, E.E. (Eds.) Microscopic Anatomy of Invertebrates, 15: 103-220. Wiley-Liss, New York.

Stevens, N. 1910. Further studies on reproduction in Sagitta. Journal of Morphology, 21: 279-319. https://doi.org/10.1002/jmor.1050210205

Stolyarova, M.V. & Kassatkina, A.P. The fine structure of the intestinal epithelium in a primitive member of Sagittidae (Chaetognatha). Tsytologiya [Cell and Tissue Biology], 32(7): 671-676. (In Russian).

Welsch, U. & Storch, V. 1983. Enzyme histochemical and electron microscopical observations on the digestive tract of Sagitta elegans. Zoologische Jahrbücher. Abteilung fur Anatomie und Ontogenie der Tiere, 109: 23-33.

Volume, Year:
Vol. 32. 2023
Vol. 31. 2022
Vol. 30. 2021
Vol. 29. 2020
Vol. 28. 2019
Vol. 27. 2018
Vol. 26. 2017
Vol. 25. 2016
Vol. 24. 2015
Vol. 23. 2014
Vol. 22. 2013
Vol. 21. 2012
Vol. 20. 2011
Vol. 19. 2010
Vol. 18. 2009
Vol. 17. 2008
Vol. 16. 2007
Vol. 15. 2006
Vol. 14. 2005
Vol. 13. 2004
Vol. 12. 2003
Vol. 11. 2002
Vol. 10. 2001
Vol. 9. 2000
Vol. 8. 1999
Vol. 7. 1998
Vol. 6. 1997
Vol. 5. 1996
Vol. 4. 1995
Vol. 3. 1994
Vol. 2. 1993
Vol. 1. 1992
Supplementa:
Suppl. 3. 2020
Suppl. 2. 2018