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Advances in the aquatic sciences

Alteration of the brood pouch morphology during gestation of male seahorses, Hippocampus kuda

Parichart Laksanawimol A , Praneet Damrongphol A B C and Maleeya Kruatrachue A
+ Author Affiliations
- Author Affiliations

A Department of Biology, Faculty of Science, Mahidol University, Bangkok 10400, Thailand.

B Center for Reproductive Biology of Economic Aquatic Animal, Institute of Science and Technology for Research and Development, Mahidol University, Nakornpathom 73170, Thailand.

C Corresponding author. Email:

Marine and Freshwater Research 57(5) 497-502
Submitted: 16 June 2005  Accepted: 8 March 2006   Published: 29 June 2006


The brood pouch of seahorses can be divided into four sequential stages based on the characteristics of the altered tissue layers during gestation: the normal stage, the embryo-carrying stage, the embryo-release stage and the repair stage. The brood pouch is composed of a folded inner pseudostratified columnar epithelium and a smooth outer stratified cuboidal epithelium. Three tissue layers between the inner and the outer epithelia are an inner loose connective tissue layer, a middle smooth muscle layer and an outer dense irregular connective tissue layer. In the normal stage, the inner loose connective tissue layer is thick and vascularised with small blood vessels; the muscle layer consists of scattered unorganised muscle fibres. In the embryo-carrying stage, the inner epithelial and inner loose connective tissue layers become distended and highly vascularised with enlarged blood vessels. In the embryo-release stage, the inner loose connective tissue layer is extensively vascularised with very large blood vessels and the smooth muscle fibres invade the outer dense irregular connective tissue layer. Structures altered during gestation gradually resume their normal condition in the repair stage. Extensive vascularisation of the brood pouch during gestation suggests an intricate paternal–embryo relationship implying other significant roles besides protective function of the pouch.

Extra keywords: embryo, reproductive season, Syngnathidae.


The authors would like to thank P. D. Round for critical reading of the manuscript. This work was supported by a grant from the Institute of Science and Technology for Research and Development, Mahidol University.


Azzarello, M. Y. (1991). Some questions concerning the Syngnathidae brood pouch. Bulletin of Marine Science 49, 741–747.

Bereiter-Hahin, J. , Richards, K. S. , Elsner, L. , and Voth, M. (1980). Composition and formation of flame cells cap: A substratum for the attachment of microorganisms to seahorse epidermis. Proceedings of the Royal Society of Edinburgh 79B, 105–111.

Carcupino, M. , Baldacci, A. , Mazzini, M. , and Franzoi, P. (1997). Morphological organization of the male brood pouch epithelium of Syngnathus abaster Risso (Teleostea: Syngnathidae): before, during and after egg incubation. Tissue & Cell 29, 21–30.
CrossRef |

Carcupino, M. , Baldacci, A. , Mazzini, M. , and Franzoi, P. (2002). Functional significance of the male brood pouch in the reproductive strategies of pipefishes and seahorses: a morphological and ultrastructural comparative study on three anatomically different pouches. Journal of Fish Biology 61, 1465–1480.
CrossRef |

Foster, S. J. , and Vincent, A. C. J. (2004). Life history and ecology of seahorses: implications for conservation and management. Journal of Fish Biology 65, 1–61.
CrossRef |

Herald, E. S. (1959). From pipefish to seahorse: a study of phylogenetic relationships. Proceedings of the California Academy of Sciences 29, 465–473.

Linton, J. R. , and Soloff, B. L. (1964). The physiology of the brood pouch of the male seahorse, Hippocampus erectus. Bulletin of Marine Science of the Gulf and Caribbean 14, 45–61.

Lourie, S. A. , Pritchard, J. C. , Casey, S. P. , Truong, S. K. , Hall, H. J. , and Vincent, A. C. J. (1999). The taxonomy of Vietnam’s exploited seahorses (family Syngnathidae). Biological Journal of the Linnean Society 66, 231–256.
CrossRef |

Lourie S. A., Foster S. J., Cooper E. W. T., and Vincent A. C. J. (2004). ‘A guide to identification of seahorses. Project Seahorse and TRAFFIC North America.’ (University of British Columbia and World Wildlife Fund: Washington D.C.) 214 pp.

Quast, W. D. , and Howe, N. R. (1980). The osmotic role of the brood pouch in the pipefish Syngnathus scovelli. Comparative Biochemistry and Physiology 67A, 675–678.

Vincent, A. C. J. (1995). Trade in seahorses for traditional Chinese medicines, aquarium fishes and curios. TRAFFIC Bulletin 15, 125–128.

Watanabe, S. , Kaneko, T. , and Watanabe, Y. (1999). Immunocytochemical detection of mitochondria-rich cells in the brood pouch epithelium of the pipefish, Syngnathus schlegeli: structural comparison with mitochondria-rich cells in the gills and larval epidermis. Cell and Tissue Research 295, 141–149.
CrossRef | PubMed |

Wetzel, J. , and Wourms, J. P. (1991). Paternal–embryonic relationships in pipefishes and seahorses (Syngnathidae). American Zoologist 31, 83A.

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