Fisheries Science

, Volume 79, Issue 2, pp 203–211 | Cite as

Structure of the intratesticular duct system for sperm emission in the starspotted smooth-hound Mustelus manazo

  • Jeong-Chae Park
  • Jeong-Hoon Lee
  • Keita Kodama
  • Hiroshi Urushitani
  • Yasuhiko Ohta
  • Toshihiro Horiguchi
Original Article Biology

Abstract

We conducted histological observation of male germ cells and reproductive organs of the starspotted smooth-hound Mustelus manazo in Tokyo Bay to reveal any abnormality in male reproductive traits, as part of a study to elucidate the factors causing recent fluctuation in abundance of the population. Spermatogenesis proceeded in spermatocysts from the germinal zone in the ventral part of the testis to the degenerative zone in the dorsal part, where the spermatozoa were conveyed into the ciliated lumina of the attached terminal branches of the intratesticular ducts. The intratesticular ducts were classified from their terminal ends into branch, stem, and collecting tubules. The ducts formed in the germinal zone and grew as the spermatocysts developed. An opening formed through the wall of each of the most mature spermatocysts into a branch tubule; bundles of spermatozoa were evacuated through this opening into the branch and then the stem tubule and subsequently into the collecting tubules in the rete testis and the efferent duct connected to the epididymis. Spermatocysts that were unable to emit sperm because of failure of adhesion to the branch tubules were disorganized in situ, as were their spermatozoa. The collapsed spermatocysts seem to be cleared by hemophagocytosis with lymphocytes and leukocytes, which may have been recruited from the epigonal organ. There were no specific abnormalities in the spermatogenesis or the morphological structure of testes, which suggested that an abnormality of male reproductive traits was not the major cause of the recent fluctuation in the population abundance of this species. Details of the intratesticular duct system for sperm emission to the epididymis are the first findings in elasmobranchs worldwide.

Keywords

Elasmobranch Mustelus manazo Intratesticular duct Sperm emission Reproduction Spermatogenesis Tokyo Bay 

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Copyright information

© The Japanese Society of Fisheries Science 2012

Authors and Affiliations

  • Jeong-Chae Park
    • 1
    • 2
  • Jeong-Hoon Lee
    • 2
    • 4
  • Keita Kodama
    • 2
  • Hiroshi Urushitani
    • 2
  • Yasuhiko Ohta
    • 1
    • 3
  • Toshihiro Horiguchi
    • 2
  1. 1.The United Graduate School of Veterinary ScienceYamaguchi UniversityYamaguchiJapan
  2. 2.Center for Environmental Risk ResearchNational Institute for Environmental StudiesTsukubaJapan
  3. 3.Laboratory of Experimental Animals, Department of Veterinary Medicine, Faculty of AgricultureTottori UniversityTottoriJapan
  4. 4.Southeast Sea Fisheries Research InstituteNational Fisheries Research and Development InstituteTongyeongKorea

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