845 



Hillman, Robert E. 1968. 



Histochemistry of mucosubstances in the mantle of the clam, Mercenaria 

 mercenaria. I. A glycosaminoglycan in the first marginal fold. Trans. Am. 

 Microsc. Soc. 87(3): 361-367. 



Sections of mantle from hard clam were subjected to a variety of histochemical 

 reactions for mucosubstances. Results of reactions on the first, or outer, 

 fold showed that a sulphated connective tissue glycosaminoglycan is secreted 

 beneath the outer epithelium in the area where most new shell is deposited. 

 The mucus was strongly alcianophilic at pH 1.0 and 2.5, and alcianophilia 

 persisted when tissues were stained with alcian blue in concentrations up to 

 0.6 M magnesium chloride. The material also reacted strongly with aldehyde 

 fuchsin and high iron diamine when those reagents were followed by alcian 

 blue. Mucus also was periodic acid-Schiff positive, which is unusual for 

 sulphated connective tissue mucosubstances. Testicular hyaluronidase had no 

 effect on staining characteristics of mucus. Because mucus was localized in 

 the shell-forming area of the mantle, and von Kossa reactions for calcium were 

 positive, it was suggested that this mucus may play some vital role in shell 

 deposition. - modified author's abstract. - J.L.M. 



846 



Hillman, Robert E. 1969. 



Histochemistry of mucosubstances in the second fold of the mantle of the 

 quahog. Proc. Natl. Shellf. Assn. 59: 5 (abstract). 



In the second fold of the mantle edge of the hard clam are two mucous cell 

 types, one secreting a sulfated acid mucopolysaccharide, the other forming 

 a neutral mucosubstance. The neutral substance is PAS-positive before and 

 after diastase digestion. It exhibits a positive PAS reaction following 

 staining with alcian blue at pH 2.5 before and after hyaluronidase 

 digestion. The acid mucopolysaccharide stains intensely with alcian blue 

 at pH 2.5 and less at pH 1. It retains alcianophilia in magnesium chloride 

 solution up to 1.0 M, and after testicular hyaluronidase digestion. It also 

 reacts strongly with iron diamine and aldehyde fuchsin when followed by 

 alcian blue. Portions of the acid stain with less intensity than others. 

 This material may be a precursor to the final, strongly sulfated acid 

 mucopolysaccharide. Acid mucopolysaccharide and neutral mucosubstance are 

 probably related in function and may be involved with calcium metabolism 

 within the mantle. - modified author's abstract - D.L. 



847 



Hillman, Robert E. 1969. 



Histochemistry of mucosubstances in the mantle of the clam, Mercenaria 

 mercenaria. II. Mucosubstances in the second marginal fold. Trans. Am. 

 Microsc. Soc. 88(3): 420-425. 



In the 2nd fold of the mantle edge of hard clam are 2 mucous cell types, one 

 secreting a sulphated acid mucopolysaccharide or glycosaminoglycan, the other 

 forming a neutral mucosubstance. The neutral mucosubstance was periodic 

 acid-Schiff (PAS)- positive prior to and following diastase digestion. It 

 also had a positive PAS reaction after staining with alcian blue at pH 2.5, 

 prior to and following hyaluronidase digestion. Usually glycosaminoglycan 

 stained intensely with alcian blue at pH 2.5 and somewhat less intensely at 

 pH 1.0. Portions of the material retained alcianophilia in solutions of 

 magnesium chloride up to 1.0 molar, and after testicular hyaluronidase 

 digestion. The material also reacted strongly with iron diamine and aldehyde 

 fuchsin when these reagents were followed by alcian blue. Methylation 

 extinguished alcianophilia in acid mucosubstance, but was partially restored 

 after saponification. Hard clams were collected from Duxbury Bay, Mass. 

 periodically to detect seasonal effects, if any. A portion of the material 

 secreted by 2nd-fold cells is similar to heparin. Heparin-like material 

 might aid in handling of Ca by the clam, and perhaps other ions such as Na 

 and CI. Its quality and quantity may depend on salinity. The remainder of 



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