The rat pinealocyte during the oestrous cycle. A morphometric study.

The involvement of the pineal gland in the oestrous cycle seems to be clear nowadays according to various types of studies, although its exact functional mechanism remains unknown. The lack of morphological studies on the pineal gland throughout the oestrous cycle has drawn us into the quantification of the surface of pinealocyte nucleoli and nuclei and lipid contents (expressed in mean area of lipid droplets with respect to the total area of pinealocytes) in each of one of the four days of the oestrous cycle: Prooestrous, oestrous, metoestrous and dioestrous. The measures of nuclei and lipid droplets were taken on photographs that were obtained from 1 micron thick sections by means of an image analyzer and the measures of nucleoli were obtained from micrography by means a point-counting analysis. One-way analysis of variance showed significant differences among nucleolar surface during the four days of the cycle. Nucleolar surface in prooestrous and oestrous was significantly smaller than in metoestrous and dioestrous and nuclear surface showed higher values in dioestrous and proestrous than oestrous and metoestrous. The relative value of lipid surface with respect to pinealocyte surface showed significant differences between oestrous and the other three days, with their minimum value in oestrous and maximum in metoestrous. We conclude that the pinealocyte have a rhythmic activity during the oestrous cycle, with a minimum close to ovulation, where the pituitary gonadotropins and ovarian hormonal levels presents a surge.