title: A morphometric study of spermatogenesis in the testes of mice of a senescence accelerated strain.
abstract: The morphometric parameters of spermatogenic cells in a mouse strain prone to accelerated senescence (SAM-P), a novel murine model of spontaneously promoted aging, were compared with those of a SAM resistant strain (SAM-R) after birth until 40 weeks (mean life span of SAM-P). A mixture of gonocytes and spermatogonia were present in the testis in 1-week-old mice, and no gonocytes were observed in 2-week-old mice. At 6 weeks of age, the absolute number of spermatogonia in SAM-P was 27% greater than that in SAM-R, whereas the cell number in 40-week-old SAM-P was 17% less than in SAM-R. Primary spermatocytes were first observed in 3-week-old animals, and the cell numbers in SAM-P at 3, 5 and 6 weeks were 78%, 31% and 25%, respectively, greater than in SAM-R, whereas the cell number in SAM-P at 40 weeks was 30% less than SAM-R. Round spermatids were first observed in all SAM-P at 4 weeks old, but 20% of SAM-R had no spermatids and the rest had only a few. At 5 and 6 weeks old, the absolute numbers of round spermatids in SAM-P were 38% and 41%, respectively, greater than in SAM-R, whereas the cell number in 40-week-old SAM-P was about 34% less than SAM-R. These results indicate that testicular maturation begins at an earlier age in SAM-P than SAM-R. Furthermore, at the age of 40 weeks signs of testicular deterioration are evident in SAM-P mice only.
authors.affiliation: Department of Animal Science, Faculty of Agriculture, Kyoto University, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Miyamoto
authors.forename: N
authors.initials: N
authors.lastname: Manabe
authors.forename: Y
authors.initials: Y
authors.lastname: Akiyama
authors.forename: T
authors.initials: T
authors.lastname: Watanabe
authors.forename: M
authors.initials: M
authors.lastname: Sugimoto
authors.forename: E
authors.initials: E
authors.lastname: Sato
mesh_terms: D000375:Aging; D000818:Animals; D001835:Body Weight; D002452:Cell Count; D013196:Dihydrotestosterone / Q000097:blood; D007985:Leydig Cells / Q000166:cytology / Q000378:metabolism; D008017:Life Expectancy; D008297:Male; D051379:Mice; D008806:Mice, Inbred AKR; D008817:Mice, Mutant Strains; D012708:Sertoli Cells; D013087:Spermatids / Q000166:cytology; D013091:Spermatogenesis; D013094:Spermatozoa / Q000166:cytology; D013737:Testis / Q000166:cytology* / Q000254:growth & development; D013739:Testosterone / Q000096:biosynthesis / Q000097:blood
chemical_list: D013196:Dihydrotestosterone; D013739:Testosterone