The submaxillary gland of 111 cadavers of humans at different ages ranging from less than 1 year to 91 years were examined histologically in an attempt at elucidation of age change of the salivary gland in man. For comparative purpose, the submaxillary gland of 198 Wistar strain rats at different ages ranging from 21 days to 21 months were also examined. Results obtained include: 1) The submaxillary gland of both rats and humans exhibited as age advanced a localized increase of the connective tissue elements in areas surrounding the excretory ducts. This change was considered to be physiological and distinct in nature from connective tissue growth following atrophy of the parenchymatous tissuses. The fatty change was observed in rare occasions in human submaxillary glands. However, increase of the connective tissue and of the fat tissue following atrophy of the parenchymatous tissues was not found in the glands of rats. 2) Secretion granules in the glandular cells of the human submaixillary gland increased in quantity toward the end of the adolescence period. The granules were found in the largest quantity during the maturity period, and to be decreased around the age of 80. In rats, granules in the excretory ducts were found to sharply increase around 3 months after birth and to remain increased until 18 months of age when they were found to be slightly decreased. 3) In rats, weight of the submaxillary gland was greater in males than in females. However, weight of the glands in female rats was greater than in males at all age levels when measured in proportion to body weight. 4) Areas occupied by the ducts (A) were compared with areas occupied by the acini (B) in a given histological section of the submaxillary gland. In humans, A was greater than B in the glands of individuals in lower age groups, and A was smaller than B in the glands of individuals in higher age groups. The inverse relation was found in the glands of rats with reference to young and old ages. This is in agreement with the fact that excretory function of the ducts of the gland is increased with age in rats. 5) These findings have demonstrated that the excretory function of the human submaxillary gland increases at the onset of the maturity period. This is in contrast to the parotid gland of man whose excretory function is known to decrease at the beginning of the maturity period when fatty change takes place in the gland. This seems to suggest a possible compensation of functions of the parotid by the submaxillary gland during and after the maturity period not only in excretory function but also in production of the salivary gland hormone.
Pulse wave velocity (PWV) was determined in 35 heathy subjects and 35 patients with hypertension, myocardial infarction and cerebral thrombosis using a noninvasive plethysmographic technique (Pulsorette s 2200). Time period was measured between the feet of the pulse waves of the carotid artery and those of the finger-top, radial, brachial, toe-top, dorsal and popliteal arteries. PWV was found to significantly increase with age in healthy subjects, most significantly between carotid and popliteal artery, but the increase was not significant between carotid and more peripheral artery. Hypertension was accompanied by increased PWV and a statistically significant increase was observed between carotid and popliteal artery. This is suspected of affecting increased peripheral resistance due to stiffness and tortuosity of the vessel wall. PWV of the patients suffering from old myocardial infarction and cerebral thrombosis showed no significant changes.