Histological Study on the Reversal Gonadal Activity in the Mussel Lithophaga truncata (Gray, 1843) during Testicular Phagocytosis (Pelecypoda - Mytilidae)

Author(s): Gaber Ahmed Saad, Mohamed M. Elghazaly

The histological observations of the gonad in the mussel Lithophaga truncata (Gray, 1843), inhabiting the Arabian Gulf in Saudi Arabia, indicated that there was only one gonadal cycle in the year. During November - February the gonadal follicles were in a quiescent state. Follicles were few in number and scattered throughout the vesicular connective tissue. In females oogonia and previtellogenic oocytes predpminated the ovary. In males the follicles were small and scattered throughout the connective tissue in the same way as females. During April - July previtellogenic oocytes began to undergo growth phase and extending towards the center of the follicles. In males spermatogenesis became more apparent and proceeded at a faster rate. The gonadal follicles ramified rapidly, and the development of gametes of both sexes was very fast. In females the vitellogenic oocytes showed prominent development. During August - October both sexes had ripe gametes. In males, the central portion of the follicles was empty because of the recent discharge of large quantities of ripe gametes. At the end of this step resorption of the gonads proceeded very rapidly and emptied follicles began to acquire an elongated form. It was found that during the process of resorption of the testicular follicles of 15 males out of 50, increased number of undifferentiated residual cells appeared inside the follicles which seems to be phagocytic in function. Many oogonia and previtellogenic oocytes appeared inside the vesicular connective tissue among the testicular follicles.

reversal gonadal activity – oogonia - previtellogenic oocytes - vitellogenic oocytes - spermatogenesis

1. Bhaby, S.; Belhsen, O. K. and Errhif, A. (2013) Mytilus galloprovincialis; gametogenesis of a colony of mussels in a fish breeding environment (Alboransea, M’diq, Morocco). J.Fisheries and A.quaculture, 4(2):110- 114.
2. Bhaby, S.; Belhsen, O. K. and Errhif, A. (2014). Mytilus galloprovincialis; Reproduction activity and mantle structure in a zone located in the northwest of the Atlantic Ocean (imessouane, morocco). J. mar. boil. Oceanogr., 3(1): 231-273
3. Bigatti, G.; Miloslavich, P. and Penchaszadeh, P. E, (2005), Sexual differentiation and size at first maturity of the invasive mussel Perna viridis (Linnaeus, 1758) (Mollusca: Mytilidae) at La Restinga lagoon (Margarita Island, Venezuela). American Malacolog. Bulletin, 20: 65–69.
4. Boltovskoy, D.; Almada, P. and Correa, N. (2011). Biological invasions: assessment of threat from ballast-water discharge in Patagonian (Argentina) ports. Environmental Science &Policy, 14: 578–583, http://dx.doi.org/10.1016/j.envsci.2011.03.007
5. Kovalyova, M. (2017): Reproductive biology of the rock-borer Petricola lithophaga (Retzius, 1788) (Bivalvia: Veneridae) in the Black Sea, Molluscan Research, DOI: 10.1080/13235818.2017.1279475
6. Lee, J.Y., Park, Y.J and Chang Y.J. (1999): Gonadal development and reproductive cycle of Gomphina melanaegis (Bivalvia; Venerida). Bulletin Marine Biol: Station; National Universty, 1:11-20.
7. Lee, J. S. ; Ku, K. ; Kim, H. ; Park, J. S. ; Park, J. J. ; Shin, Y. K. and Jeon, M. A. (2012). Indirect evidence on sex reversal with sex ratio in Tegillarca granosa (Bivalvia: Arcidae) and Ruditapes philippinarum (Bivalvia: Veneridae). Development and Reproduction, 16: 177-183.
8. Lee, J. S. (2015). Sex and Sex Reversal of Bivalves. Korean J. Malacol. 31(4): 315-322. http://dx.doi.org/10.9710/kjm.2015.31.4.315
9. Miller, M. and Batt, G. (1973). Reef and Beach Life of New Zealand, William Collins (New Zealand) Ltd, Auckland, New Zealand.
10. Naval, S. H. (2013). Temperature data. http://www.hidro.gov.ar . (Accessed 20 November 2013) Soot-Ryen T (1955) A report on the family Mytilidae. AllanHancock Pacific Expedition, 20: 1–154
11. Park, J. J. ; Kim, H. ; Kang, S.W. ; An, C.M. ; Lee, S.H.; Gye, M. C. and Lee, J.S. (2012). Sex ratio and sex reversal in two-year-old class of oyster, Crassostreagigas (Bivalvia: Ostreidae). Development and Reproduction, 16: 385-388.
12. Powell, A. W. B. (1979). New Zealand Mollusca, William Collins Publishers Ltd, Auckland, New Zealand ISBN 0-00-216906-1.
13. Sueiro, M. C. (2014). Marine fouling invasions in ports of Patagonia (Argentina) with implications for legislation and monitoring programs Marine Envir. Res., 99:60–68. http://dx.doi.org/10.1016/j.marenvres.2014.06.006
14. Sueiro, M. C. ; Bortolus, A. and Schwindt, E. (2011). Habitat complexity and community composition: Relationships between different ecosystem engineers and the associated macroinvertebrate assemblages. Helgoland Marine Research, 65: 467–477.http://dx.doi.org/10.1007/s10152-010-0236-x