Embriología vascular

Embryonic Vascular Development

Introduction to Vascular Embryology

• Dr. Gabriel Piero Talo introduces the topic of vascular embryology, emphasizing that vascular and cardiac tissues originate from mesodermal layers starting in the third week of embryonic development.

• The heart begins to beat around day 22 or 23, initiating embryonic blood flow.

Processes of Vascular Formation

• Two primary processes are involved in forming the vascular system: angiogenesis (differentiation of mesoderm cells into specialized vascular cells) and vasculogenesis (development of arterial and venous blood vessels).

• Mesenchymal cells differentiate into angioblasts influenced by endothelial growth factor and fibroblast growth factor type 2, leading to the formation of blood islands.

Development Stages

• Angioblasts aggregate to form endothelial cords; these structures develop small cavities that expand as more angioblasts aggregate.

• By weeks four to five, a primitive heart and a network of arterial and venous blood vessels become visible.

Pharyngeal Arch Formation

• Arterial vasculogenesis begins with pharyngeal arch formation during week four, where six aortic arches appear sequentially.

• The first aortic arch forms on day 22, contributing to the pulmonary trunk's anterior part while connecting with dorsal aortas.

Aortic Arch Development

• By day 26, arches three, four, and six develop further; they connect with the pulmonary sac and dorsal aortas.

• The first arch partially disappears but gives rise to maxillary arteries; the third arch contributes to pulmonary plexuses.

Venous System Development

Initial Venous Structures

• By week four, three main veins emerge: vitelline veins, umbilical veins (which will later obliterate), and cardinal veins which form the primary venous network.

Formation of Inferior Vena Cava

• The inferior vena cava's development starts in week five primarily through cardinal vein networks merging with vitelline veins.

Cardinal Vein Fusion

• In week six, cardinal veins fuse creating common cardinal veins leading towards significant venous structures like the inferior vena cava.

Vascular Development and Formation of Renal Veins

Early Vascular Network Formation

• The vascular network begins to develop with a central dilation known as the subcardinal anastomosis, which is crucial for renal vein formation.

• By the end of this week, branches from the supracardinal veins contribute to the origins of renal veins. This process is significant in understanding venous development.

Progression Towards Venous Maturation

• By the eighth week, anterior cardinal veins merge cephalically to form brachiocephalic veins, initiating a downward generation through the posterior cardinal vein. The inferior vena cava becomes visible at this stage.

• The inferior vena cava forms from parts of both the anterior cardinal vein and common right cardinal vein, indicating complex interactions in venous development.

Final Stages of Venous Development