Environmental Biology of Fishes

, Volume 97, Issue 9, pp 1013–1029 | Cite as

Ontogenetic testicular development and spermatogenesis in rays: the Cownose Ray, Rhinoptera bonasus, as a model

  • Gregg R. Poulakis
  • Harry J. Grier


An understanding of testicular anatomy, development, and seasonality has implications for studies of morphology, behavior, physiology, and bioenergetics of males. Ontogenetic testicular development and spermatogenesis is essentially unknown for chondrichthyans. We examined embryo, juvenile, and adult male Cownose Rays (Rhinoptera bonasus) during development and throughout the annual reproductive cycle. Spermatogonia and Sertoli cells originated from germ cells and somatic cells, respectively, in the embryonic testicular germinal epithelium. In embryos and small juveniles, discrete regions of spermatocyst production appeared within a series of papillae that projected from the dorsal surface of each testis. Because these papillary germinal zones appeared to proliferate through ontogeny, we hypothesize that (1) the germinal zones of juvenile and adult testes are derived from embryonic testicular papillae that form from the germinal epithelium and (2) the papillae become the dorso-central portion of the distinct testicular lobes that form at maturation due to increased spermatocyst production. Our observations indicate that testicular development and the process of spermatogenesis began during embryonic development and increased in scale through ontogeny until maturation, when distinct testicular lobes formed and began enlarging or shrinking based on the annual reproductive cycle. Gonadosomatic indices peaked corresponding to seasonal increased sperm production between January and April, just prior to the April–June mating period. In all life stages, spermatocysts had efferent ducts associated with them from their formation through all stages of development. Year-round presence in the Charlotte Harbor estuarine system, Florida made R. bonasus a good model for beginning to understand ontogenetic gonad development and spermatogenesis in chondrichthyans, especially viviparous rays.


Elasmobranch Germinal epithelium Histology Reproduction Spermatocyst Viviparity 



We thank the volunteers who collected R. bonasus and recorded data during dissections, especially Amy Timmers, Sarah Erickson, Chrystal Murray, Julia Shaw, Jackie DeAngelo, and J. Patrick Casey. We also thank Fish and Wildlife Research Institute histology laboratory staff and volunteers for sample processing, especially Noretta Perry and Yvonne Waters. Thanks to Joe Quattro and Mark Roberts for sequencing and analyzing the mtDNA samples. Thanks to Theresa Cody, Jan Landsberg, and Yasu Kiryu of the Fish and Wildlife Research Institute for access to their Olympus BX50 compound light microscope with DP71 camera. Thanks to Kevan Main and Nicole Rhody of the Mote Aquaculture Research Park for access to their Olympus BX53 compound light microscope with DP72 camera. Bland Crowder, Phil Stevens, and two anonymous reviewers improved earlier versions of this manuscript. Jessica Carroll produced the final versions of Figs. 1, 2, 3, 4, 5, 6, 7, 8, and 9. Special thanks to the Save Our Seas Foundation for sponsorship and to Matt Ajemian and Julie Neer for organizing the stingray symposium at the 2013 American Elasmobranch Society meeting in Albuquerque, NM, where some of these data were presented for the first time. Animals were sacrificed humanely according to normal animal care and ethics practices. This work was supported in part by Florida recreational saltwater fishing license sales and U.S. Department of the Interior, U.S. Fish and Wildlife Service, Federal Aid for Sportfish Restoration Project Number F-43 to the Florida Fish and Wildlife Conservation Commission.


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Copyright information

© Springer Science+Business Media Dordrecht 2014

Authors and Affiliations

  1. 1.Florida Fish and Wildlife Conservation CommissionFish and Wildlife Research Institute, Charlotte Harbor Field LaboratoryPort CharlotteUSA
  2. 2.Florida Fish and Wildlife Conservation CommissionFish and Wildlife Research InstituteSt. PetersburgUSA

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