Cell and Tissue Research

, Volume 273, Issue 1, pp 149–162

Gonadal sex differentiation in Alligator mississippiensis, a species with temperature-dependent sex determination


  • Craig A. Smith
    • School of Biological SciencesMacquarie University
  • Jean M. P. Joss
    • School of Biological SciencesMacquarie University

DOI: 10.1007/BF00304622

Cite this article as:
Smith, C.A. & Joss, J.M.P. Cell Tissue Res (1993) 273: 149. doi:10.1007/BF00304622


Temperature of egg incubation determines sex in Alligator mississippiensis hatchlings. To define the timing and morphology of sexual differentiation, alligator gonads were examined histologically and ultrastructurally throughout embryogenesis. At the male-producing temperature (33° C), the onset of testis differentiation occurred in most embryos during developmental stages 21–22, when a number of somatic cells in the medulla of the gonad became enlarged, forming presumptive Sertoli cells. Some enlarged somatic cells were also observed at the female-producing temperature (30° C) during gonadogenesis, but they were less widespread than at 33° C. Ovarian differentiation at 30° C began slighlty later, during stage 22–23, and was characterised by proliferation of germs cells in the cortex of the gonad. Testis formation in alligators may depend upon presumptive Sertoli cells differentiating prior to a critical event in embryogenesis, such as germ cell proliferation and meiosis. If follows that ovary formation occurs if this requirement is not met, as at lower incubation temperatures.

Key words

Temperature-dependent sex determinationGonadal differentiationSertoli cellsTestisOvaryAlligator mississippiensis (Crocodilia)

Copyright information

© Springer-Verlag 1993