Seminal plasma: an essential attribute to spermatozoa.

The biochemical composition of seminal plasma (SP) is very complex and variable among species. Advances in reproductive technologies reveal SP as a nutritive-protective medium for sperm cells suspended in it, and some SP components are very important for sperm metabolism, as well as sperm function, survival, and transport in the female reproductive tract. Biochemistry of SP is a relatively modern but rapidly expanding field of research, particularly concerning the biological significance of the various biochemical constituents of SP. However, identification of active factors in SP and mechanisms by which they act are not sufficiently understood in different species. Especially in camelids, the origin, composition, and function of the viscous component of SP remain a mystery, and only some biochemical and morphological characteristics of SP have been described. In this review, we focus on the current understanding of physiological and biochemical properties of SP in ruminants and camelids.