A quantitative immunocytochemical study on the gonadotrophs in the female rats during the estrous cycle

In the present paper, the immunocytochemical method was used to determinethe cyclic morphological changes of the rat's pituitary gonadotrophs during an estrouscycle. Four groups of female rats were decapitated at the four different phasesduring the estrous cycle. Paraffin coronal sections of cephalic, middle, and caudalportions of the pituitary gland were mounted and stained with a-hCG and HRPlabelled antibody method. The number and size of stained gonadotrophs werequantified by using chequer and point-counting method under hight microscope.The results were as follows: 1) the average number of gonadotrophs per mm~2 was:662±36 in diestrus; 633±102 in proestrus; 449±106 in estrus and 427±76 in metestrus respectively. Student-Newman-Keulls test showed that during thediestrus and proestrus the numbers of stained gonadotrophs were significantlygreater than those in estrus and metestrus (n = 12, P0.05). 2) The averagestained area (μm~2) of the gonadotrophs was 106±11.70 in diestrus, 107.00±13.10in proestrus, 95.70±10.30 in estrus and 101.00±5.95 in metestrus. The differ-ences were statistically insignificant. 3) The distributive characteristic of stainedgonadotroph types showed cyclic changes during the estrous cycle. These resultssuggest that cyclic changes of stained gonadotroph number and cellular structuremight bear a close relation to cyclic changes of serum concentrations of gonado-tropins during the rat estrous cycle.