Biology of Reproduction, Vol 3, 23-30, Copyright © 1970 by Society for the Study of Reproduction

Sustained Fertility After CdCl2 Injection by a Non-scrotal Mammal, Suncus murinus (Insectivora, Soricidae)

¹ Department of Biology, Slippery Rock State College, Slippery Rock, Pennsylvania 16057

The effects of subcutaneous CdCl₂ injection were studied on the testes of 69 musk shrews, Suncus murinus, and 36 laboratory mice, Mus musculus. No gross damage was observed in the testes and epididymides of shrews 120 days after injection of 0.03 mM CdCl₂/kg body weight. None of 16 shrews examined experienced a significant reduction in testis weight (108.4 ± 1.8% SE of pretreatment control) and tubule diameter (96.5 ± 1.0% SE) 20-90 days after injection. The testes of 16 mice under comparable conditions showed drastic weight loss (31.9 ± 2.5% SE) and involution in tubule diameter (54.9 ± 3.4% SE). The high protein diet of the shrews did not confer cadmium protection to mice, and absence of testicular damage in shrews could not be attributed to insufficient CdCl₂ dosage. The estimated LD₅₀ of CdCl₂ in 49 shrews was approximately 0.06 mM/kg. No fertility depression was indicated by reduced siring success or by increased postnatal mortality of young born to 30 females served by four injected studs. A temperature differential of approximately 1.1 C was found to exist between cremaster sac and rectum of 40 shrews. This small temperature difference may be involved in conferring the relative CdCl₂ resistance to the testes of this shrew. Application of different investigative approaches to the questions of testicular cadmium and heat sensitivity are discussed relative to these findings in Suncus.