Feulgen microspectrophotometric analysis of deoxyribo‐nucleoprotein organization in larval and adult freshwater sponge nuclei

Microspectrophotometric measurements of nuclei of adult choanocytes and archeocytes and larval archeocytes and flagellated ectodermal epithelia from stages III and IV were undertaken on tissues from the freshwater sponge, Eunapius fragilis (Leidy). The condensed nuclei of differentiated choanocytes and stage IV flagellated epithelial cells presented integrated extinction values about 64% of those obtained for either adult or larval archeocytes. This suggests that such measurements represent sensitive indicators of deoxyribo-nucleoprotein-complex organization; thus, nuclear differentiation. Further, no large population of G2 (4C) nuclei was found among these populations as has been reported in two classes of coelenterates.