Searching for the Spermatozoon: A Historical Review of Identification Techniques
THE MICROSCOPE
2019, Volume 67:2, pp. 83–95
DOI
https://doi.org/10.59082/LSFW4744
AUTHOR
William H. Wilson
ABSTRACT
Although the existence of the spermatozoon was first noted more than 300 years ago, the understanding of its function, physicochemical structure, and viability is a relatively recent discovery. The structure of the sperm is distinctive: it is composed of an oblong-shaped head, a neck, a midpiece, and a flagellating tail, and is approximately 50–75 μm long. Seminal fluid is gelatinous and sticky, and is composed of water, salts, organic matter, proteins, and lipoids in an alkaline state. Dry seminal stains appear grayish-white, and impart a stiff, starchy feeling to an absorbent material. Methods for detection of these stains include tactile and chemical tests, ultraviolet light or alternate light sources, and microcrystal tests, although noted nonspecific interferences exist for these methods. Recovery procedures of dry stains include cutting, scraping, and immersion, and acidic destruction or sonic oscillation of the substrate cloth. Unstained sperm may be microscopically detected, but may be confused with Trichomonas vaginalis or other interferences to the untrained eye. Chemical staining is utilized in order to aid in sperm identification by individually coloring the acrosome, nucleus, and/or tail. Staining, counterstaining, and other procedures for the purpose of identification are described here.