Human ovarian teratomas, also known as dermoid cysts, are common benign tumors and comprise 10-20% of all ovarian cysts.  Ovarian teratomas arise from primordial germ cells and are thought to result by several mechanisms during germ cell maturation, namely by: (a) failure of meiosis I, (b) failure of meiosis II or (c) endoreduplication of a haploid ovum.  Our objective is to conduct a detailed study of the biology and genetics of naturally occurring human ovarian teratomas.  The major scientific goals are the elucidation of the mechanisms by which ovarian teratomas arise and the relative frequency of each mechanism; the utilization of ovarian teratomas for gene mapping, and the understanding of the process and role of meiosis and recombination in germ cells.  The specific aims are to establish a repository of at least 200 ovarian teratomas and corresponding normal ovarian tissue, to determine the mechanism of origin of each ovarian teratoma and to estimate the relative frequency of each mechanism.  for this purpose, each teratoma and the corresponding normal tissue will be cultured for cytogenetic analysis using various banding techniques to detect chromosomal heteromorphisms.  In addition, polymorphic enzyme and DNA markers will be used to determine the zygosity at several loci on the chromosomes.  Furthermore, we propose to develop, extend and apply statistical methods to study gene-centromere and gene-gene linkage and to construct multilocus gene maps of specific chromosomes; to compare genetic maps thus constructed to available genetic maps derived from family studies to assess the utility of ovarian teratomas for gene mapping; and to synthesize the above information to understand the process of recombination and the relationship between recombination and meiosis in human germ cells.  The results of our studies will be important not only for purposes of gene mapping but for understanding the basic process of recombination.