STRUCTURAL COMPOSITION OF SHORTHORN BULL TESTES AND DAILY SPERMATOZOA PRODUCTION AS DETERMINED BY QUANTITATIVE TESTICULAR HISTOLOGY

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Abstract
The structural composition of the testes, the sperm output, and the daily sperm production were determined in seven 18-month-old Shorthorn bulls. The testicular components classified composed the following percentages of the total testis volume: spermatogonium nuclei,.62%; primary spermatocyte nuclei, 4.57%; secondary spermatocyte nuclei,.16%; spermatid nuclei, 3.52%; spermatozoa,.34%; tubular cytoplasm, 57.79%; lumen, 4.67%; basement membrane, 2.60%; intertubular space, 23.63%; and Sertoli cells, 2.04%. The seminiferous tubules made up 76.4% of the testis volume. It was estimated that the testes contained on the average 1630 m (range 960–2240 m) of seminiferous tubules. The tunica albuginea comprised 12.8% of the testis weight.Three procedures are described for measuring daily sperm production from quantitative testicular histology, and the results obtained with Shorthorn bull testes are presented. The limitations of the three procedures are discussed. It was estimated that 18-month-old Shorthorn bulls produced 5.3 × 109 sperm per day. This represented a production of 16.9 million sperm per gram of testis per day. Within a given species sperm production appears to be primarily a function of testis size. The seven bulls averaged 2.7 × 109 sperm per ejaculate when semen samples were collected every other day with an electroejaculator. This represented about 25% of the sperm production by the testes.