Variations in the number of nucleoli in the granulosa cells of the domestic fowl during follicular growth.

1. The proportions of granulosa cells containing one, two, or more nucleoli were determined in ovarian follicles of the domestic fowl (Gallus domesticus). Follicles ranged in size from 5 to 37 mm diameter. 2. The greatest proportion of cells (65%) contained one nucleolus. Cells containing two nucleoli were fewer (29%) and those containing more than two were rare (6%). 3. There was a tendency for the proportion of multinuclear cells to decrease with increasing size of the follicle. Conversely there was a similar tendency for the proportion of cells with single nucleoli to increase with size of the follicle. These relationships are curvilinear. 4. Suitable linear models confirmed these observations (P less than 0.005). 5. These results may provide an explanation for the previously reported progressive decrease in cellular DNA as the follicle increases in size.