The cell wall cannot be observed through light microscopy or simple stains. It may be demonstrated by microdissection, reaction with specific antibodies, mechanical rupture of the cell, differential staining procedures or by electron microscopy.

Tulane University

The cell wall is a structure found in most prokaryotes and some eukaryotes that envelopes the cell membrane. Working in combination with cytoskeletal elements, the cell wall maintains the cell's morphology and protects it from changes in osmotic pressure.

Cell Wall

Al-mohanna, Moshtaq & H., quine. (2016). MORPHOLOGY AND CLASSIFICATION OF BACTERIA. 

Morphology and Classification of Bacteria

Viewing the Cell Wall

The cell wall is composed of peptidoglycan, a mucopeptide (formed by N acetyl glucosamine & N acetyl muramic acid) linked to peptide chains. Teichoic acids are embedded into the cell wall and may be linked to lipids (Lipoteichoic acid). These Lipotechoic acids connect peptidoglycan to the cytoplasmic membrane and gives the cell wall its rigidity. 

Composition of the Cell Wall

Peptidoglycan, also referred to as murein, is the major component of bacterial cell walls and is uniquely found in bacteria. Structurally, it resembles a fabric-like meshwork layer composed of long chains of alternating N-acetylglucosamine (NAG) and N-acetylmuramic acid (NAM) molecules. These chains possess significant two-dimensional tensile strength because peptide bridges connect the NAG and NAM units within each peptidoglycan layer.

Peptidoglycan

The cell walls of some eukaryotic cells—such as plants, fungi, algae, and certain protists—provide structural stability and protection from environmental stresses like desiccation, changes in osmotic pressure, and traumatic injury. The chemical composition of these walls varies: plants use cellulose; fungi use chitin; and algae and protists can utilize biogenic silica, calcium carbonate, agar, or carrageenan.

Eukaryotic Cell Wall

Bacteria are traditionally classified into gram-positive, gram-negative, and atypical groups based on their staining patterns, which are determined by their cell wall properties. Gram-positive bacteria have a thick peptidoglycan layer that retains stain, gram-negative bacteria have a thin peptidoglycan layer surrounded by an outer membrane, and atypical bacteria cannot be stained by standard Gram stain procedures.

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