Expression of argyrophilic nucleolar organizer regions (AgNORs) in the harderian gland of male and female hamsters during postnatal development.

The expression of argyrophilic nucleolar organizer regions (AgNORs) was studied in the different secretory cell types of the Harderian gland of male and female Syrian hamsters during postnatal development. Mean AgNOR area was calculated for each cell type in paraffin sections from 7-, 14-, 21-, 28-, 45- and 90-day-old animals. AgNOR content was similar in male type I-cells and in female cells, decreasing in both cell types from the 7th to the 14th day, increasing afterwards at the 21st day, and remaining at relatively stable levels from that point to the end of the study. AgNOR content of male type II-cells was greater than in other cell type studied, and was greater in 45- and 90-day-old animals than in 28-day-olds. Changes of AgNOR content in type I-cells of male and female hamsters during the first two weeks seem to be related to changes in proliferative activity while metabolic activity might be responsible for changes taking place later on. Our results also support that male type I- and type II-cells have a different biological behaviour and that type II-cells are far from being degenerating cells.