Periodic acid-silver methenamine, a fairly specific technique for glycoprotein detection, was used to stain a variety of rat tissues, in the hope of confirming the existence of a carbohydrate-rich "cell coat" at the surface of mammalian cells. It was found that nearly all cells are coated by a thin layer of stained material. Around fibrocytes and migrating blood cells, the layer is uniform and merges with the ground substance. In the nervous system, cells and processes are surrounded with a layer whose density increases in synaptic clefts. Around epithelial cells, the layer outlines apical microvilli, follows lateral interspaces, and extends between cells and basement membrane. The layer is continuous with the middle plate of desmosomes and can be followed within the wide portion of terminal bars. In contrast, staining usually vanishes when two adjacent plasma membranes fuse to form tight junctions. These findings indicate that the stained layer is a "cell coat" located outside the plasma membrane. Since the cell coat is also stained by colloidal thorium, a technique for detection of acidic carbohydrates, this structure presumably contains not only glycoprotein(s) but also acidic residues. The carbohydrates may play a role in holding cells together and in controlling the interactions between cells and environment.

https://rupress.org/jcb/article-pdf/32/1/27/1262940/27.pdf

Electron microscope observations on the carbohydrate-rich cell coat present at the surface of cells in the rat.

The special value of methods that color both acidic and vicinal hydroxyl groups in the histochemical study of mucins. with revised directions for the colloidal iron stain, the use of alcian blue g8x and their combinations with the periodic acid‐schiff reaction*

Neoplastic transformation results in a wide variety of cellular alterations that impact the growth, survival, and general behavior of affected tissue. Although genetic alterations underpin the development of neoplastic disease, epigenetic changes can exert an equally significant effect on neoplastic transformation. Among neoplasia-associated epigenetic alterations, changes in cellular glycosylation have recently received attention as a key component of neoplastic progression. Alterations in glycosylation appear to not only directly impact cell growth and survival but also facilitate tumor-induced immunomodulation and eventual metastasis. Many of these changes may support neoplastic progression, and unique alterations in tumor-associated glycosylation may also serve as a distinct feature of cancer cells and therefore provide novel diagnostic and even therapeutic targets.

/pdf/protein-glycosylation-in-cancer-3qtxqudawd.pdf

Protein Glycosylation in Cancer

The organization of ground substance and basement membrane and its significance in tissue injury disease and growth.

Spatial and temporal expression pattern of N-cadherin cell adhesion molecules correlated with morphogenetic processes of chicken embryos☆

Periodic acid acts upon the 1,2 glycol linkage (-CHOH -CHOH-) of carbohydrates in tissue sections to produce aldehyde (RCHO+RCHO) which can be colored with Schiff s reagent The method can be used 

J. F. A. McManus

Papers

Histological and Histochemical Uses of Periodic Acid