The importance of these classifications is based on retrospective and prospective studies in different populations which indicate a close association between certain subtypes of IM and the risk of gastric carcinoma. Throughout foetal life, gastric surface mucus is a mixture of sialomucins and neutral mucins with a gradual decrease of sialomucins and neutral mucins being predominant at 23 weeks, reaching an adult pattern at birth. O-acylated mucins and sulphomucins are not detected. Straight crypts and regular architecture. Crypts are lined by mature columnar cells and goblet cells.
Paneth cells are often present.
The goblet cells secrete sialo- and occasionally sulphomucin. Paneth cells are rarely observed. Distortion of crypt architecture is more pronounced and loss of differentiation and cellular atypia are more marked than in type 2. Paneth cells are usually absent. Characterised by columnar mucous-secreting cells and goblet cells resembling colonic mucosa.