Juxta-Glomerular Apparatus

MENOFIA FACULTY OF MEDICINE EGYPT HISTOLOGY DEPARTMENT

Students from class 35 Section A

Made by :

• SiteAnatomy

• Definition• componentsHistology

• Functionphysiology

Outlines

Anatomy

Histology

It is a specialization of glomerular afferent arteriole and the distal convoluted tubule of the corresponding nephron .

Definition

Components

Macula densa

Renin secreting (JG) cells

Extraglomerular mesangial cells

Macula Densa

It is an area of closely packed ,specialized

cells lining the DCT as it comes close to the

vascular pole.

L/M• columnar• Apical deeply stained

nucleus.

E/M:• Basal crowded mitochondria .• Extremely thin basement

membrane.• Sensitive to Na ions

concentration in DCT.

Renin secreting (Juxta-Glomerular) cells

They are modified smooth muscle cells

of the afferent arteriole and small

numbers are present in the efferent

arteriole

L/M• Features of myoepithelial cells:

rounded nucleus , granular cytoplasmE/M:

• Contain mature &immature membrane bounded granules of renin enzyme.

Extraglomerular mesangial cells(Polar cushion – Polkissen cells –lacis cells )

Lies in the triangular region between

AA&EA at sides & macula densa at the

base.

L/M• Flat branched basophilic

cell.

NB:• They are continuous with

similar cells known as the intra-glomerular mesangial cells between endothelium & basal membrane.

Juxta-Glomerular apparatus

TriangleApex : Glomerular mesangial cellsSides : afferent & Efferent arterioleBase : Macula DensaInside : Lacis cells

Physiology

Function 1.Secretion

of renin

2. Secretion of

erythropoietin

Secretion of renin

Kidney secretes 90% of erythropoietin hormone

Thanks