MAST-CELLS IN THE HARDERIAN-GLAND OF FEMALE SYRIAN-HAMSTERS DURING THE ESTROUS-CYCLE AND PREGNANCY - EFFECTS OF THE LIGHT-DARK CYCLE

The number of identifiable mast cells and the intraluminal area occupi ed by porphyrin deposits was studied on semithin sections from female hamster Harderian glands during the estrous cycle and pregnancy. Altho ugh the serum levels of estradiol, progesterone, luteinizing hormone a nd follicle stimulating hormone exhibited significant changes througho ut the cycle, no correlation between these changes and the variations in the number of recognizable mast cells was observed. However both du ring diestrous 1 and proestrous cycles, the number of identifiable mas t cells was higher at midnight than at noon (in 14 h light:10 h dark p hotoperiod with lights on at 07.00 h). A more exhaustive study reveale d the presence of 'degranulated mast cells' which were not stained wit h toluidine blue. Thus, a diurnal cycle in degranulation might occur i n the Harderian glands from female hamsters. No significant variations were observed in the area occupied by intraluminal porphyrin deposits during the estrous cycle. However, both the relative number of mast c ells and the area occupied by intraluminal porphyrins decreased from d ay 4 of pregnancy to day 14 showing a strong correlation. The Harderia n glands from female Syrian hamsters might provide a useful model for the study of mast cell degranulation during porphyria.