Abstract
Background:
Numerous plant and animal species have β-defensins, antimicrobial peptides involved in immunity and reproduction. Beta-defensin 126 (DEFB126) belongs to the β-defensin family and is a vital component of sperm function. It regulates the capacitation and sperm-egg interaction.

Aim:
There is no evidence of DEFB126 expression in the dromedary camel's sperm or reproductive tract.

Methods:
The current work used immunohistochemical (IHC) and quantitative real-time polymerase chain reaction (qRT-PCR) methods to clarify the distribution and expression of DEFB126 in the sperm and male reproductive tract (MRT) of dromedary camels in the time of rutting. Samples of fresh and epididymal sperm, testicular, epididymis, ductus deferens, and male accessory gland tissues were obtained from twenty male camels.

Results:
The results of IHC showed that the fresh and epididymal sperms had a positive immunoreaction to DEFB126 antibodies. Also, all parts of the testicles, epididymis, vas deferens, prostate, and bulbourethral glands were positively stained to various degrees with a strong immunoreaction in the epididymal's tail. qRT-PCR results showed that expression levels of DEFB126 mRNA varied in the fresh and epididymal sperms and throughout all parts of the MRT; the tail of the epididymis had the most significant expression levels (P<0.05).

Conclusion:
This study's results indicated that DEFB126 protein is expressed in the sperm and MRT of the dromedary camel, with the acrosomal cap of the sperm and the epididymis tail exhibiting the highest levels of expression. These findings imply that DEFB126 could be involved in the reproductive processes of sperm maturation, capacitation, and sperm-zona recognition.

Key words: Camel, DEFB126, Immunohistochemistry, Male reproductive tract, qRT-PCR, Sperm