Histochemical Study of Early Embryo Implantation in Rats

Abstract

SUMMARY:Embryo implantation is the process that results in attachment of the conceptus to the uterine wall. In this histochemical study, we investigated the early stage of embryo implantation in rats by morphological analysis and by the detection of total proteins and glycosaminoglycans using hematoxylin-eosin, toluidine blue at pH 4.0 (TB), and Xylidine Ponceau at pH 2.5 (XP). In non-pregnant females, the uterine layers could be clearly distinguished and showed the normal histology of the organ. In pregnant females, an increase in the number of cells and a reduction in the interstitial space were observed in the endometrium close to the implantation sites. The blastocyst was partially inserted in the endometrium, with the observation of the inner cells mass around the blastocyst cavity surrounded by trophoblastic cells. TB staining revealed mild metachromatic basophilia, which was more evident in the endometrial stroma around the implantation site. Histochemical staining with XP was also more intense in the stroma close to the site of implantation. On the other hand, histochemical staining with either TB or XP was more discrete at sites distant from the conceptus. This study demonstrated changes in the endometrial stroma in areas adjacent to the site of embryo implantation, with variations in glycosaminoglycans and proteins as demonstrated by the detection of anionic and cationic radicals, respectively.

Developmental and reproductive toxicity hazard characterization of 2‐amino‐2‐methyl‐1‐propanol (AMP)

“…The day the plug is observed is considered gestational day 0 (GD0) (Moore et al, 2018). Implantation occurs when the conceptus attaches to the uterine wall, and typically occurs during GD 4–5 in rats (Spósito & Santos, 2011). Finally, parturition (birth) occurs most often on Day 21 in rats (Charles River, 2022).…”

The spatial and temporal distribution of cationic and anionic radicals in early embryo implantation

“…The aforementioned results indicate that the changes of signal molecules during the implantation period are not only affected by hormones but also related to the local effects of blastocysts. The previous study detected the cationic and anionic radicals using Xylidine ponceau (XP) at pH 2.5 and toluidine blue (TB) at pH 4.0 during the early phase of embryo implantation of rats [5]. Although the initial interaction between the concept and the uterus is a complex phenomenon, little research has been done on the spatial and temporal distribution of cationic radicals and anionic radicals during the time of implantation.…”