A study was conducted to correlate the occurrence of -glycerophosphatase activity in a linted cultivar and a lintless hybrid line using Gomori's lead precipitate technique (modified by Barka & Anderson, 1982) at the light and electronmicroscope level.

No activity occurred in the lintless line. In the linted cultivar the enzyme activity was associated with cell wall, nucleus, nucleolus and endoplasmic reticulum (ER). There was no indication of any enzyme activity before anthesis, but as the fiber cells expanded on the day of anthesis, activity gradually appeared in the cell wall and nucleus. Further, as the fiber started elongating, i.e. one day post anthesis, nearly all the activity was localized in the region where directional growth of the fiber cell was occurring, i.e. micropylar side. By two day post anthesis, the enzyme activity was mainly concentrated in the nucleolus and ER.

These results show that the phosphatase activity is associated with areas where distinct anatomical and perhaps catabolic changes are occurring during fiber differentiation. Interestingly, the enzyme activity was not a percursor to, but coincided with, these changes of fiber development.