Juxtaglomerular apparatus of the human kidney: correlation between structure and function

Area of Science:

• Nephrology
• Renal Physiology
• Cell Biology

Background:

• The juxtaglomerular apparatus (JGA) is a critical component of the human kidney involved in blood pressure homeostasis.
• Understanding the cellular composition and structural dynamics of the JGA is essential for comprehending renal function.

Purpose of the Study:

• To conduct an electron microscopic and morphometric evaluation of the human kidney's juxtaglomerular apparatus (JGA).
• To elucidate the cellular components, structural organization, and adaptive responses of the JGA under varying physiological conditions.

Main Methods:

• Electron microscopy was utilized to examine the ultrastructure of the JGA.
• Morphometric analysis was performed to quantify cellular volumes and surface areas within the JGA.

Main Results:

• The JGA comprises epithelioid cells of arterioles, Goormaghtigh cells, and macula densa, richly innervated by sympathetic nerves.
• The macula densa possesses a large surface area (approx. 66 cm2) and contacts the juxtaglomerular cell complex (JGC) via the Goormaghtigh cell field.
• JGC volume ranges from 26 to 40 mm3; decreased blood pressure induces JGC hypertrophy and hyperplasia, potentially transforming Goormaghtigh and mesangium cells into epithelioid cells.

Conclusions:

• The JGA is a complex endocrine structure with significant adaptive capacity.
• Morphological changes in the JGC, including cellular transformation, are key responses to reduced blood pressure, highlighting its role in blood pressure regulation.