chorionic terminal villus

terminal villus

The most distal part of a chorionic villus. A chorionic terminal villus is a grape-like structure characterized by a high degree of capillarization and highly dilated sinusoids. A terminal villus has less stroma and a discontinuous cytotrophoblast layer, and contains 4–6 fetal capillaries per cross section. It exhibits a diameter ranging from 40 to about 80 μm.

Tür Vessel
Ana Yapı chorionic floating villus
Latince Adı terminal villus

Sıkça Sorulan Sorular

What is a chorionic terminal villus?
A chorionic terminal villus is the most distal branch of the chorionic villous tree, representing the primary functional unit of gas and nutrient exchange in the placenta. It is a grape-like structure approximately 40 to 80 micrometers in diameter, characterized by a high degree of capillarization, dilated sinusoidal capillaries, and a thin exchange membrane.
What structural features make terminal villi efficient for exchange?
Terminal villi are optimized for exchange through several features: they have 4 to 6 highly dilated sinusoidal fetal capillaries per cross-section, a discontinuous cytotrophoblast layer that reduces diffusion distance, a thin syncytiotrophoblast layer forming vasculosyncytial membranes where capillaries are apposed to the trophoblast surface, and a minimal stromal core. Together these features maximize the surface area and minimize the barrier thickness for diffusion.
What is the vasculosyncytial membrane in a terminal villus?
The vasculosyncytial membrane is the region within a terminal villus where the dilated capillary endothelium is in extremely close contact with the syncytiotrophoblast. In this zone, the intervening stroma is absent and the fused basement membranes of the capillary and trophoblast reduce the diffusion distance to less than 2 micrometers. This is the site of most rapid oxygen and carbon dioxide exchange between fetal and maternal blood.
How do terminal villi relate to sinusoidal capillary dilations?
The capillaries within terminal villi are not uniformly narrow; they display sinusoidal dilations (enlargements) at acute bends. These dilations slow fetal blood flow, increase the contact time for exchange, and create the vasculosyncytial membranes. The overall pattern of narrow and dilated segments gives the capillary a characteristically tortuous and beaded appearance on histological sections.
What pathological conditions specifically affect terminal villi?
Distal villous hypoplasia (immaturity) involves underdevelopment of terminal villi relative to gestational age, reducing exchange capacity and associated with growth restriction. Increased syncytial knots on terminal villi indicate hypoxia-related accelerated aging. Avascular terminal villi result from downstream obliteration of fetal capillaries, indicating fetal vascular malperfusion. Excessive perivillous fibrin deposits can entrap and obliterate terminal villi, causing massive perivillous fibrin deposition syndrome.

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This content is for educational and informational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider for medical decisions.

Data sources: Terminologia Anatomica, Foundational Model of Anatomy, Wikidata.