Cytology and duration of the cycle of the seminiferous epithelium of the boar; duration of spermatozoan transit through the epididymis

Abstract

The cycle of the seminiferous epithelium of the boar was divided into eight stages which are described. The relative frequencies of the stages were determined for ten Yorkshire and ten Lacombe boars approximately 11 months of age. The mean relative frequencies for stages 1 through 8 were 10.8, 14.4, 3.5, 11.6, 8.9, 20.3, 18.5 and 12.0%, respectively. Generally, there was a constancy of the relative frequencies of the stages between breeds, among boars within breeds and between testes within boars.The absolute duration of the cycle of the seminiferous epithelium and the duration of spermatozoan transit through the epididymis were determined by injecting a single dose of 19 mCi of thymidine-methyl-H3 into the marginal ear vein of each of four Yorkshire (15.2 months old) and four Lacombe boars (14.9 months old). Unilateral castrations were performed at 0.2, 11.5, 20.0, 24.0 and 25.0 days after the isotope injection. Two intact and two unilaterally castrated animals were ejaculated for eight and seven weeks, respectively, to determine the interval between the thymidine-H3 injection and the appearance of the isotope in the ejaculated semen. Autoradiographs were prepared from the testis tissues and the semen smears. The most mature germ cells that incorporated the thymidine-H3 were the late preleptotene primary spermatocytes. Twenty-five days afer injection the label had progressed from late preleptotene primary spermatocytes to spermatozoa leaving the testes. Epididymal transit times for four boars (ejaculated daily) were 9, 10, 10 and 12 days. The duration of one cycle of the seminiferous epithelium based on 12 estimates was 8.6 i 0.1 days. The durations of stages 1 through 8 were 0.9, 1.2, 0.3, 1.0, 0.8, 1.7, 1.6 and 1.0 days, respectively. The life span of primary spermatocytes was 12.3 days, of secondary spermatocytes 0.4 days, of spermatids with round nuclei 6.3 days, o f spermatids with elongated nuclei 1.5 days, and of spermatozoa 6.2 days.Within the seminiferous tubules of sexually mature animals the cells are not arranged at random but are organized in a series of well defined cellular associations or stages. These stages succeed one another in any given area with the passage of time. This orderly sequence gives rise to the socalled "cycle of the seminiferous epithelium". Leblond and Clermont ('52b) defined this cycle as the "series of changes occurring in a given area of the seminiferous epithelium between two successive appearances of the same cellular association". The cycle of the seminiferous epithelium has been divided into stages on the basis of the development of the spermatid acrosome (Leblond and Clermont, '52a, b) or on the basis of the morphology and cytology of the germ cells and their relative position within the seminiferous tubules ANAT. REC., 161: 171-186.(Curtis, '18; Roosen-Runge and Giesel, '50; Ortavant, '59). The latter approach was used in this study.The number of cycles of the seminiferous epithelium required for the completion of spermatogenesis depends on the species and on...

Reproductive Characteristics of Boars during and after Exposure to Increased Ambient Temperature2

“…This time interval is 41 days for bulls (Orgebin, 1961). The duration of sperm transit through the epididymis is similar for boars and bulls and ranges from 9 to 12 days for boars (Swierstra, 1968) and 8 to 11 days in bulls (Orgebin, 1961). Other possible reasons for the different recovery times for boars and bulls from the cessation of heat stress until ejaculation of sperm with normal motility could be the stage of spermatogenesis affected or the severity and duration of increased testicular temperature.…”

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Return of testicular function after vaccination of boars against GnRH: consequences on testes histology

“…The contribution of the eight stages of spermatogenesis (Swierstra, 1968) was counted in one hundred tubules at 400-fold magnification. The spermatogenic cells were differentiated from Sertoli cells after GATA-4-staining.…”

Comportamento de monta e características seminais de suínos jovens landrace e large white

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