A specific and obligatory role for long chain polyenoic acids (LCPA) in spermatogenesis is suggested by several lines of evidence. Our objective is to elucidate that role with initial emphasis on 1) localization of LCPA and lipids containing them to specific classes of cells and structures, 2) description of LCPA metabolism, transport and uptake with respect to cell type and stage of spermatogenesis, 3) determination of effects of testis maturation and effectors of spermatogenesis on distribution of LCPA concentration, metabolism and uptake. Prerequisite to reaching these objectives is the enabling objective, separation of the testis cell population into specific cell types and stages of differentiation. We will sort suspensions of mouse testis cells into types and stages by electronic cell sorting on the basis of light scatter and fluorescence of viable stains. We will quantitate LCPA and other fatty acids in purified cells and in complex lipids and measure biosynthesis, catabolism, retroconversion and uptake of LCPA by monitoring in vivo and in vitro radioisotope incorporation into cells and component lipids. We will use various dietary, chemical and physical interventions to determine the effects of modification of spermatogenesis on patterns of LCPA distribution, uptake and metabolism. These studies will further our understanding of spermatogenesis.