[Sequence of vascular closing mechanisms beginning post partum]

Area of Science:

• Perinatal Medicine
• Developmental Biology
• Vascular Anatomy

Context:

• The perinatal period is characterized by significant physiological adaptations, including the closure of fetal circulatory structures.
• Understanding the timeline of these closures is crucial for diagnosing and managing congenital cardiovascular anomalies.

Purpose:

• To analyze the morphological changes and time sequence of the closure of the ductus arteriosus, ductus venosus, and umbilical vessels.
• To investigate the cellular mechanisms, such as medial contraction and intimal proliferation, involved in vessel closure.
• To determine if neonatal factors like immaturity or hypotrophy affect the closure process.

Summary:

• A study of 120 perinatal deceased and 30 postnatal deceased individuals examined the morphological closure of fetal vessels.
• Medial contraction and intimal proliferation, key to vessel closure, were completed by one month post-birth for ductus venosus and umbilical vessels, and by three months for the ductus arteriosus.
• Intimal proliferation initiated closure of the ductus arteriosus antenatally, with primary thrombosis being a rare cause of closure. Dystrophic changes were observed in later months.
• No significant differences in closure patterns were noted between immature/hypotrophic and mature/eutrophic neonates.

Impact:

• Provides a detailed timeline for the natural closure of critical fetal circulatory vessels.
• Establishes a baseline for identifying abnormal closure patterns potentially indicative of pathology.
• Highlights the role of intimal proliferation in ductus arteriosus closure, offering insights for potential therapeutic targets.