Qualitative and quantitative changes in the histology of the human submandibular salivary gland during post natal growth.

One submandibular gland from each of 33 necropsies on children aged between birth and 14 years was examined histologically. A simple point-counting method established the volume fractions of various component tissues of the glands and these were compared between five age groups. Below 30 days of age acini and ducts were often immature and widely separated by abundant, vascular, connective tissue. After six months of age glandular structure was more compact with little intralobular connective tissue. Lymphocytic foci were numerous in many of the glands from children aged over six months with a prevalence higher than that previously established for young adults. Consolidated intraductal deposits were found in just under half the glands, mostly after the age of six months. The mean volume proportion of acinar tissue was 43% in the age group 0-30 days but had increased to 64% in the 6 month -- 2 year age group. Over the same period there were reductions in the mean proportional volumes of ducts, vascular and connective tissues. After the age of two years changes in the volume proportions of component tissues were not significant. The developmental and growth-associated changes of the present investigation were opposite in direction to the ageing changes which previous studies have shown occur over the whole of adult life. Moreover, the point at which reversal occurs seems to be in early adult life rather than in childhood.