Effect of daily spermatozoan production but not age on transit time of spermatozoa through the human epididymis.
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Daily spermatozoan production, numbers of epididymal spermatozoa, and transit times of spermatozoa through different regions of the epididymis were determined in 38 men, aged 20-49 or 50-79 yr. Specimens were obtained at autopsy within 24 h of death due to traumatic injury or heart failure. Subjects were in apparent good health prior to death, and death was not preceded by an extended period of hospitalization. Daily spermatozoan production per testis (DSP/T) and numbers of epididymal spermatozoa were determined from counts of maturation-phase spermatids or epididymal spermatozoa in tissue homogenized in a Waring blender. Epididymal transit time was calculated as the number of spermatozoa in a given region of the epididymis or in the entire epididymis divided by DSP/T of the connected testis. Parenchymal weight, spermatozoan production rate, numbers of epididymal spermatozoa, and epididymal transit time were similar (p greater than 0.05) between paired testes or epididymides. Men were divided into four groups on the basis of age and DSP/T. Since there was no (p greater than 0.05) effect of age on epididymal transit time, men in different age groups were combined within their respective group on the basis of DSP/T. In the group with high DSP/T, DSP/g parenchyma was much higher and epididymal transit time was much faster. However, parenchymal weights and numbers of epididymal spermatozoa were similar (p greater than 0.05) between DSP/T groups. The similarity in number of spermatozoa in epididymides of men whose DSP/T differed by threefold is consistent with the inability of the human epididymis to store many spermatozoa when no blockage is present.(ABSTRACT TRUNCATED AT 250 WORDS)