The human placenta: new perspectives on its formation and function during early pregnancy

Area of Science:

• Reproductive Biology
• Developmental Biology
• Human Embryology

Background:

• The placenta is crucial for fetal development, preceding embryonic growth.
• Traditionally, maternal blood was thought to nourish the early placenta.
• New evidence suggests a shift in understanding early placental support.

Purpose of the Study:

• To investigate the role of histotrophic nutrition in early human placental development.
• To explore the signaling pathways regulating endometrial gland secretions.
• To link impaired decidualization and gland function to pregnancy complications.

Main Methods:

• Analysis of endometrial gland secretions during embryogenesis and organogenesis.
• Utilizing endometrial gland organoids to study hormonal regulation.
• Correlating placental development with hormonal signaling (estrogen, progesterone, prolactin).

Main Results:

• Histotrophic nutrition from endometrial glands, rich in glucose, lipids, and growth factors, supports early trophoblast proliferation.
• Hormonal signaling, particularly prolactin, upregulates endometrial gland secretion.
• A feed-forward dialogue between trophoblast, decidua, and glands stimulates placental development independently of the embryo.

Conclusions:

• Early placental development is primarily supported by endometrial gland secretions (histotroph).
• Impaired decidualization and reduced prolactin secretion may compromise histotroph supply.
• Improving endometrial health prior to conception could mitigate pregnancy disorders like miscarriage, growth restriction, and pre-eclampsia.