Sertoli cells of intra-abdominal testes from 25 naturally occurring, unilaterally cryptorchid, West African pygmy goats between the ages of 1-30 months were morphologically examined by light and transmission electron microscopy. Ultrastructurally, Sertoli cells in the intra-abdominal testes from 1-month-old goats were columnar and contained ovoid nuclei. The cytoplasm depicted clusters of rough endoplasmic reticulum cisternae (RER). In 3- to 4-month-old animals nucleolonemas of the Sertoli cells were associated with vesicles; the cytoplasm contained RER and areas of whorls of smooth endoplasmic reticulum. An abundance of lipid droplets was accompanied by lipofuscin granules in the cytoplasm. In 6- to 8-month-old goats RER cisternae presented circular or irregular profiles in the cells with an augmentation of cytoplasmic lipid droplets and lipofuscin granules. In 12- to 15-month-old animals intercellular spaces in the seminiferous epithelium exhibited focal expansions. Nuclear profiles of the Sertoli cells were irregular. In 24- to 30-month-old animals the Sertoli cells were in an advanced stage of degeneration.