When grown in the nutrient-rich BG medium, A.ovalisporum isolated from
Lake Kinneret developed longer filaments and larger heterocysts and akinetes
than the natural populations. In these cultures, the cells were 2-5 um in diameter
and 5-8 um long; heterocyst diameter was 5 urn (Table I). The akinetes were 8-10
Um in diameter and 15-20 um long. When inorganic N was excluded from the
medium, most of the trichomes had three heterocysts and three akinetes, and in
most cases the akinetes were adjacent to the heterocysts.