| dc.description | In this paper we evaluated the morphologic and quantitative aspects of the implantations sites in uteruses of female pinealectomized and/or submitted to the constant illumination rats. The experimental groups were: I - normal female rats maintained in a clear/dark cycle of 12/12 hours, for two months, mated and euthanasiated in the 6th day of pregnancy (control); II - female sham-pinealectomized rats maintained in a clear/dark cycle of 12/12 hours, for two months, mated and euthanasiated in the 6th day of pregnancy (control); III - female pinealectomized rats, maintained in a clear/dark cycle of 12/12 hours, for two months, mated and euthanasiated in the 6th day of pregnancy; IV - normal female rats maintained in constant illumination for two months, mated and euthanasiated in the 6th day of pregnancy; V - female sham-pinealectomized rats, maintained in constant illumination for two months, mated and euthanasiated in the 6th day of pregnancy; VI - female pinealectomized rats, maintained in constant illumination for two months, mated and euthanasiated in the 6th day of pregnancy. The means of the implantations sites showed that there were significant differences, where the groups III, IV, V and VI differed from the groups II and I, which presented the highest means. The groups III, IV, V and VI didn't differ amongst themselves. The sites in the control groups revealed the presence of small gaps containing blood, trophoblastic cells, and some polyploid cytotrophoblasts. In the groups III, IV, V and VI it was evidenced well-developed gaps at the sites, with trophoblasts, cytotrophoblasts with high polyploidy degree and syncytiotrophoblasts. In conclusion the pinealectomy and/or constant illumination reduce of the number implants in female rats besides to stimulate the development of the implantation sites, indicating thus a probable function of the melatonin in the viability of implantation of the blastocyst | |
