Localization of tumor necrosis factor in the canine testis, epididymis and spermatozoa LOCALIZATION OF TUMOUR NECROSIS FACTOR IN THE CANINE TESTIS

Abstract 22 23 Tumour necrosis factor (TNF), formerly known as Tumour necrosis factor alpha is now 24 regarded as a natural component of the mammalian seminal plasma (SP). Although not 25 completely clarified, its functions in the SP have been associated with paradoxal roles, 26 such as sperm survival in the female genital tract, while at high levels negatively affect 27 sperm survival and fertility potential. Recently, it has been discovered that canine 28 inseminated spermatozoa display a strong immunoreaction for TNF when lining the 29 female endometrium. As a continuation of this finding, the present work aimed at 30 documenting TNF localization in the canine testes and epididymis and in freshly 31 ejaculated spermatozoa (SPZ) through immunohisto-or cytochemistry. 32 Immunoreaction for TNF was found in all samples used. In the dog testis, TNF 33 immunoexpression was limited to the seminiferous tubules, where late round spermatids 34 (SPD) showed weak intensity of immunostaining, whilst elongating and elongated SPD 35 evidenced moderate and the residual bodies a strong intensity. In the epididymis, a 36 gradual progressive increase of TNF immunolabelling was found throughout the 37 epididymal regions, ranging from a weak intensity at the caput epididymis to a moderate 38 intensity at the cauda. TNF immunolabelling was found in mature SPZ during the 39 epididymal transit and also in freshly ejaculated SPZ, which showed a strong mid-piece 40 immunolabelling. Data presented here provide important information on expression of 41 TNF in spermatozoa, which is acquired by the SPZ during their formation at the testis. It 42 further provides the basis for subsequent studies on the physiological importance of 43 cytokines in sperm function. 44 4