SpermatoStages™
A model of the seminiferous epithelium cycle
Track germ cells through spermatogenesis — forward and backward in time — across more than 20 species, from rat and mouse to human, bull, horse, and many more.
SpermatoStages is an interactive, web-based research tool for predictive modeling of the stages in the cycle of the seminiferous epithelium, data analysis, and visualization of germ cells during spermatogenesis. It is useful across the biomedical sciences, including reproductive biology, toxicology, pathology, and veterinary and human medicine. Pick a species, pick a germ cell, and predict where it will be after any number of days.
Useful for:
- Identifying stage-specific cellular associations
- Identifying target cell types in toxicity studies
- Identifying cell-specific gene deletion effects
- Planning sample collections
- Learning the kinetics of spermatogenesis — the cycle, mitosis, meiosis, and germ cell differentiation
- Comparing differences between animals and species
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What it does
- Stage grids (maps of the seminiferous epithelial cycle) for each species, strain, and breed
- Forward and backward prediction of germ cell positions across the cycle
- Adjustable cycle length and stage frequencies per species
- Stage histology images with cell labels and schematic drawings
- Interactive learning tool for the kinetics of spermatogenesis and the seminiferous epithelium cycle
- Runs in any modern browser — Mac, Windows, Linux, iPad, Chromebook
Built on the work of
Hess RA (1990). Quantitative and qualitative characteristics of the stages and transitions in the cycle of the rat seminiferous epithelium: light microscopic observations of perfusion-fixed and plastic-embedded testes. Biology of Reproduction 43(3): 525–542.
Hess RA, Chen P (1992). Computer tracking of germ cells in the cycle of the seminiferous epithelium and prediction of changes in cycle duration in animals commonly used in reproductive biology and toxicology. Journal of Andrology 13(3): 185–190.
About the name
SpermatoStages is the web-based continuation of STAGES, a program begun in 1986 by Dr. Rex Hess and rewritten for MS-DOS, Windows and Mac computers between 1988 and 1995. In 2026 it was rewritten for the web, and STAGES was renamed SpermatoStages™ to distinguish it from other software with the same name. Read the history →