Pl. III · Laxus reticularis — reticular connective tissue

The plate

The specimen, drawn

Pl. III

A fine branching mesh of type III collagenA structural protein in the dermis that provides strength and elasticity., holding soft organs open from the inside. You will not see it in H&E — it takes silver.

Habitat & range

Where it lives

Body map

Wherever blood cellsThe basic structural and functional units of life. or immune cells need somewhere to sit, there is a reticular net holding the room open for them.

Range

• Lymph nodes, in chains through the neckNarrow region just below the head; common fracture site., armpit, chest, abdomen and groin.
• The spleen, as the framework of both red and white pulp.
• Red bone marrow, holding the developing blood cells in place.
• The liverA large organ that produces bile, detoxifies blood, and stores nutrients., as the scaffold the hepatocyte plates are built on.
• Anywhere soft tissue needs a skeleton that does not take up room.

Collection record

• Add your slide numbers here.

Niche

What it does for a living

Being the furniture. Reticular tissue makes a three-dimensional scaffold out of fine branching type III collagen, and the cells that matter — lymphocytes, macrophages, developing blood cells — live in its spaces rather than being part of it. It holds a soft organ open without making it stiff, which is why you can squeeze a lymph node and it springs back.

field collected specimen

How to know it on sight

• A fine black or dark brown branching net — silver stain, not H&E.
• Fibres are thin, even in calibre, and they branch and rejoin rather than running in bundles.
• The spaces are full of free cells that are not attached to the fibres.
• No single direction; the net is three-dimensional and looks tangled in any one plane.

Specimen 1

A lymph node at high power. Follow one fibre to where it branches, and then follow both branches.

Specimen 2

Marrow. Here the net holds developing blood cells and fat cells together in the same space.

People keep calling her by the wrong name

Look-alikes

Two plates. Read the line underneath each one before you decide.

Areolar connective tissue

Areolar also has no grain, but its fibres are thick pink bundles of type I; reticular fibres are fine, even, and only show up with silver.

Elastic connective tissue

Verhoeff makes elastin dark too. Elastic fibres run in long wavy parallel lines; reticular fibres branch into a net and go nowhere in particular.

Examine it yourself

The virtual slide

Zoom in on a lymphoid follicle until the individual lymphocytes separate. The net holding them is reticular tissue, and in this stain you will have to infer it from the spaces rather than see it directly.

Virtual slide courtesy of Histology Guide.

Field notes

Why this organism

A mycelium is the largest part of a fungus and the part nobody sees. It threads through the whole of the soil as a branching net, holding the ground together and feeding everything that lives in it, and then puts up a mushroom for a week. Reticular tissue works the same way round: the net is the organ, and the cells you actually came to look at are just the things living in it.