Implantation involves a complex process between the embryo and uterus and is crucial to further embryonic development. In this histochemical study, we investigated the early stage of embryo implantation and artificial decidualization in mice by the detection of total proteins and glycosaminoglycans using toluidine blue at pH 4.0 (TB) and Xylidine Ponceau at pH 2.5 (XP). TB staining showed mild metachromatic basophilia, which was more visible in the endometrial stroma around the implantation site in day 5 of pregnancy, and the level of glycosaminoglycans was more intense near the site of implantation on day 6, 8. Histochemical staining with XP was observed more intense in the stroma close to the site of implantation, especially in day 8 of pregnancy. At sites distant from the blastocyst were observed more discrete by staining with either TB or XP. Compared with TB, XP were more evident in the stroma around the uterine lumen under artificial decidualization. This study demonstrated changes in glycosaminoglycans and proteins by the detection of anionic and cationic radicals in the endometrial stroma adjacent to the site of embryo implantation during peri-implantation, post-implantation and artificial decidualization.
Embryo implantation varies widely in placental mammals. We review this variation in mammals with a special focus on two features:the depth of implantation and embryonic diapause. We discuss the two major types of implantation depth, superficial and interstitial, and map this character on a well-resolved molecular phylogenetic tree of placental mammals. We infer that relatively deep interstitial implantation has independently evolved at least eight times within placental mammals. Moreover, the superficial type of implantation represents the ancestral state for placental mammals. In addition, we review the genes involved in various phases of implantation, and suggest a future direction in investigating the molecular evolution of implantation-related genes.
In adult animals, the significance of circadian clocks in the regulation of physiology is well established. However, the physiological roles of embryonic clock genes on early embryo development, implantation and perinatal survival are still unclear. In the present study, using genotyping, embryo culture and transfer, the early embryo development, implantation, and perinatal survival of Bmal1+/+, Bmal1+/- and Bmal1-/- embryo were studied. At cleavage stage, the genotype ratio of Bmal1+/+, Bmal1+/- and Bmal1-/- embryo was 1:1.97:0.95, respectively (p > 0.05). Morula or early blastocyst developmental ratio was 83.8 +/- 14.3, 87.1 +/- 9.2 and 88.7 +/- 1 4.5%, respectively (p > 0.05). After transferring of the three types of embryos to pseudopregnant wild-type mice, the implantation sites 4days later was 7.7 +/- 0.9, 7.2 +/- 1.2 and 7.5 +/- 0.5 (n=4, F = 0.265, p = 0.773). Mean litter size of the mice after transferring with the three types of embryos was 5.5, 6.0, and 3.0 (n = 3, F = 30.3, p = 0.001). The development of Bmal1 null embryos was not impaired in preimplantation and early implantation stages, but the litter size had a trend to decrease.