ANATOMY

Detailed explanation-1: -Implantation bleeding occurs when a fertilized egg implants into the lining of your uterus (endometrium) during conception. After sperm fertilizes the egg, it’s called an embryo. The embryo travels down the fallopian tubes into your uterus. At this point in your menstrual cycle, the endometrium is thick and vascular.

Detailed explanation-2: -The outer wall of the blastocyst i.e., the trophoblast gets attached to the endometrium of the uterus during implantation.

Detailed explanation-3: -Implantation. Once the embryo reaches the blastocyst stage, approximately five to six days after fertilization, it hatches out of its zona pellucida and begins the process of implantation in the uterus.

Detailed explanation-4: -In humans, following the stage of hatching that takes place around four to five days after fertilization, the process of implantation begins. By the end of the first week, the blastocyst is superficially attached to the uterine endometrium. By the end of the second week, implantation has completed.