Basement membrane

Question 1

Sheets of specialised ECM with GAGs for epithelial anchorage

Acts as a mechanical barrier, boundary between epithelium and connective tissues

A diffusion barrier, can be a molecular sieve or permeability barrier depending on pore size as determined by GAG arrangement (like in kidneys)

Question 2

How many sheet does it form?
- What types of cells/ tissue produce the sheet
- Name the sheets
- Name the substances which make up the sheets

Answer 2

Forms 2 sheets:

Basal lamina is synthesised by epithelial cells and contains anchoring fibrils of type 4 collagen which extend into the reticular lamina

Reticular lamina is produced by the connective tissue and contains fibres and collagen bundles on which fibrils loop