New insights into the normal menstrual cycle-regulatory molecules

Area of Science:

• Reproductive Biology
• Endocrinology
• Cellular Biology

Background:

• Endometrial growth and regression are primarily hormone-driven.
• Emerging evidence suggests autocrine/paracrine regulatory molecules play a role.
• These molecules influence endometrial regeneration, cell survival, and maturation.

Purpose of the Study:

• To review the dynamic changes in endometrial patterns during the normal menstrual cycle.
• To examine the role of various regulatory molecules in these changes.
• To understand the molecular mechanisms underlying endometrial proliferation, maturation, and breakdown.

Main Methods:

• This is a review article, synthesizing existing research.
• It examines the expression and activity of growth factors, angiogenesis factors, proliferation markers, anti-apoptotic proteins, matrix metalloproteinases, and their inhibitors.
• The focus is on their changing patterns throughout the proliferative and secretory phases of the menstrual cycle.

Main Results:

• Growth factors and proliferation markers are elevated during the proliferative phase, aiding regeneration.
• Proteins preventing extracellular matrix degradation and apoptosis support endometrial cell survival.
• A shift towards apoptosis occurs in the late secretory phase, with increased expression of maturation-related substances.

Conclusions:

• Regulatory molecules are crucial in modulating endometrial dynamics beyond ovarian hormones.
• The balance between proliferation and apoptosis is tightly controlled by these factors.
• Dysregulation, particularly involving matrix metalloproteinases and their inhibitors, likely contributes to menstruation in the absence of implantation.