This proposal is for support of research to study a new organelle of mammalian germ cells termed a dictyosome-like structure (DLS). This structure occurs in guinea pig spermatocytes and spermatids in large numbers. DLS have been noted in testes including primates (preliminary indication are that they will also be found in man). The DLS are composed of stacks of 2-17 saccules. Each saccule averages about 200 angstrom units in thickness (membrane plus lumen) and is separated from adjacent saccules in the stack by an intersaccular space of about 120 angstrom units. Microtubule-like structures about 100 angstrom units in diameter bridge both the inter- and intra-saccaular spaces. At least some of the microtubule-like structures often appear in linear arrays or in clusters of 3-4. Although bearing a distinct resemblance to Golgi apparatus, DLS and Golgi apparatus frequently coexist in the same cell. The presence of microtubule-like elements makes the DLS clearly different from Golgi apparatus and places it as candidate as a new organelle unique to certain stages of spermatogenesis. Because DLS contain distinct microtubule-like elements and appear to carry out some function restricted to requirements unique to late stages of germ cell development in the testis, these structures emerge as potential targets for development of drugs applicable to control of fertility in the male. The objectives of this proposal are to study the DLS of testis germ cells to learn: 1. more about their structure, function and distribution among species, and 2. to what extent DLS contain unique macromolecules (i.e., a unique tubulin-like or tubulin-associated protein) against which specific blocking drugs could be developed. A correlative approach will be emphasized in which information from electron microscopy and cytochemistry will be combined with cell fractionation and biochemical analyses.