Implantation of Blastocyst

1. During implantation, the uterus is in the secretory phase, characterized by coiled glands and arteries and a succulent tissue.
2. The endometrium consists of three distinct layers: a superficial compact layer, an intermediate spongy layer, and a thin basal layer.
   

   Implantation of Blastocyst
3. The human blastocyst typically implants in the anterior or posterior wall of the uterus, embedded between gland openings.
4. If fertilization does not occur, the endometrium undergoes changes during the menstrual phase.
5. Venules and sinusoidal spaces become packed with blood cells, leading to extensive bleeding into the tissue.
6. During menstruation, blood escapes from superficial arteries, and fragments of stroma and glands are expelled over 3-4 days.
7. The basal layer, supplied by its own arteries, serves as the regenerative layer during the subsequent proliferative phase, rebuilding glands and arteries.