Studies on diffusing factors: The hyaluronidase activity of testicular extracts, bacterial culture filtrates and other agents that increase tissue permeability.

AQUEOUS extracts of mammalian testicle contain a factor that dramatically increases the permeability of the tissues to injected fluids [McClean, 1930; 1931; Hoffman & Duran-Reynals, 1931]. This can be demonstrated by the rapid disappearance of the bleb following intracutaneous injection of these extracts and by the rapid spread through a large area of skin of any suitable coloured indicator that may be injected together with them. This factor is associated with the germinal epithelium and can be extracted from spermatozoa [McClean, 1931]. Factors with similar diffusing properties have been obtained from the most diverse sources, for example, from ifitrates and extracts of staphylococcus and streptococcus [Duran.Reynals, 1933], from organisms of the gas-gangrene group and virulent pneumococci [McClean, 1936], from extracts of malignant tissues [Duran-Reynals & Stewart, 1931; Boyland & McClean, 1935], from snake and spider venoms [Duran-Reynals, 1939] and'from leeches [Claude, 1937]. Various methods for the partial purification of testicular extracts and of baclFrial culture ifitrates of the gas-gangrene group have been described [Morgan & McClean, 1932; Favilli, 1936; Claude & Duran-Reynals, 1937; McClean, 1936; Madinaveitia, 1938; 1939, 1, 2; Mannozzi-Torini, 1939], but no naturally occurring diffusing factor has been isolated in the pure state. Nobody had succeeded in elucidating the mechanism whereby this diffusion effect is produced until Chain & Duthie [1939] reported that purified preparations of testicular diffusing factor exhibit a remarkable mucolytic activity characterized by a rapid fall in the viscosity of mucoprotein preparations and the liberation therefrom of reducing substances. This observation suggested that the mucolytic and diffusing -activities might be due to the same factor and that the spread in the tissues might be due to the action of the enzyme on the mucin-like interfibrillar substance in the collagen of the dermis. It was obviously important to confirm the observations of Chain & Duthie, to determine whether diffusing factors from other sources exhibit a similar mucolytic activity and to make a comparative study of these enzymes. Madinaveitia & Quibell [1940] have already described a viscosimetric method whereby testicular mucinase may be accurately estimated and they have investigated many of the characters of the reaction. During the progress of our own observations Meyer et al. [1940, 1] reported the hydrolysis of hyaluronic acid by bacterial enzymes; it had previously been shown by Meyer & Palmer [1936] that the mucoproteins of vitreous humour and umbilical cord contain a, mucopolysaccharide which they had designated by the term hyaluronic acid. More recently