The effects of growing of Sertoli cells isolated from rat seminiferous epithelium by a modified procedure, and responses of these cells to dBcAMP or FSH stimulation was estimated using morphological methods. The modified isolation procedure included repeated mechanical rinsing of tubule pieces with a modified EDTA containing Hanks medium. Moreover, streptornase instead DNase was added to the trypsine containing medium and this resulted in a better dispersion of tubule components. The culture conditions remained unmodified. A high degree homogeneity of the cultured cell population and an evident reactivity of these cells to dBcAMP and FSH was achieved. Furthermore, an observation of giant cells, visible in monolayer among the typical Sertoli cells, is discussed in this paper. Contrary to small number of myoid cells, being survived in the culture, these giant cells did not show positive reaction to alkaline phosphatase.