“…Although hormone concentrations, rates of sperm production, Sertoli cell number, germ cell: Sertoli cell ratio and other related variables have been the subject of considerable research (Savard & Goldzieher, 1960;Lindner, 1961;Bedrak & Samuels, 1969;Swierstra et ai, 1974;Berndtson et ai, 1974Berndtson et ai, , 1979Berndtson et ai, , 1983Weisner & Kirkpatrick, 1975;Thompson et ai, 1977;Amann et ai, 1979;Johnson & Neaves, 1981;Squires et ai, 1981;Jones, 1983;Johnson & Thompson, 1983, 1987Jones & Berndtson, 1986), only a few of these variables have been subjected to com¬ parisons between the left and right testis within individual stallions. Such information is of basic value in characterizing normal reproductive biology of the stallion.…”