Prostaglandin discovery and

Table VIII shows that the concentration of PGEi equivalents in several sources is very small, a fact which accounts greatly for the delayed development of the prostaglandins. The special problem of collecting large quantities of some of these substances richest in prostaglandins is obvious. Sheep vesicular glands eventually proved to be the most practical source. The prostaglandin discovery and development timetable shown in Table IX, when compared with the steroid timetables, reveals some of the differences as well as similarities between these developments.

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