Related Experiment Video
Updated: Aug 6, 2026
Utero-tubal Embryo Transfer and Vasectomy in the Mouse Model
Published on: February 28, 2014
The effect of ethyl-, methyl- and hydroxyethyl-nitrosourea on the mouse testis
Abstract:
Hybrid male 101 X C3HF1 mice were given intraperitoneal injections of methyl-, ethyl- and hydroxyethyl-nitrosourea and killed 3-16 days later. All compounds were similar in that all differentiating spermatogonia from type A1 to early type B were killed by 50 mg/kg and higher doses of ENU and by 75 mg/kg MNU. Cells exposed in leptotene to 100 and 250 mg/kg ENU and 455 mg/kg HENU showed a delayed response with degeneration in pachytene 5 days later. Labeling prior to exposure to ENU indicated that the effect of stage of the mitotic cycle on sensitivity to cell killing is less marked than for radiation. This may be the explanation for the s-shaped mutation induction curve obtained with ENU in contrast to the humped dose-response curve observed for radiation.
Insights
Ethyl-, methyl-, and hydroxyethyl-nitrosourea (ENU, MNU, HENU) target spermatogonia in mice. ENU and MNU cause cell killing, while ENU and HENU induce delayed germ cell degeneration, impacting mutation induction curves.
Area of Science:
- Toxicology
- Genetics
- Reproductive Biology
Background:
- Nitrosoureas are alkylating agents with known mutagenic and carcinogenic properties.
- Understanding the effects of nitrosoureas on male germ cells is crucial for assessing reproductive risks.
Purpose of the Study:
- To investigate the differential toxicity and cell-killing effects of methyl-, ethyl-, and hydroxyethyl-nitrosourea (MNU, ENU, HENU) on mouse spermatogonia.
- To compare the sensitivity of different spermatogonial stages to these compounds.
- To explore the relationship between cell killing and mutation induction curves.
Main Methods:
- Intraperitoneal injection of hybrid male mice (101 X C3HF1) with varying doses of MNU, ENU, and HENU.
- Histological examination of testes at 3-16 days post-injection to assess germ cell survival and morphology.
- Spermatogonial labeling studies to determine the cell cycle effects on sensitivity.
Main Results:
- ENU and MNU demonstrated significant killing of differentiating spermatogonia (Type A1 to early Type B) at doses of 50 mg/kg and 75 mg/kg, respectively.
- ENU and HENU exposure at specific doses led to delayed germ cell degeneration observed in pachytene cells 5 days post-exposure.
- The sensitivity of the mitotic cycle stages to ENU-induced cell killing was less pronounced compared to radiation.
Conclusions:
- ENU and MNU exhibit potent cytotoxic effects on early spermatogonial populations.
- The observed delayed degeneration suggests complex cellular responses to ENU and HENU.
- The differential sensitivity across cell cycle stages may explain the distinct mutation induction curves (s-shaped for ENU vs. humped for radiation).
