The spleen, in common with the lymphoid tissues elsewhere, shows atrophy, sometimes to an extreme degree, so that instead of the normal weight of 7 oz. it weighs a few drams only. The capsule is thrown into folds, and is somewhat opaque; from atrophy of the pulp and Malpighian corpuscles the vessels and fibrous trabeculae become prominent. The thymus, contrary to the general opinion that it undergoes involution long before puberty, has been found by Hammar[166] to increase in size up to puberty when involution begins, but proceeds so gradually that even in old age it is functional.
The thyroid, unless there is cystic change, is smaller than natural; thus out of 40 thyroid glands from individuals between the ages of six months and 77 years the smallest was in a woman aged 77 (Hale-White[167]). In colour it is darkish brown and on section rather dry. Dr. Donaldson, Lecturer on Pathology at St. George’s Hospital, has specially examined 19 thyroid glands from patients between the ages of 57 and 93; of these five showed cystic change; they all showed increase in the amount of fibrous tissue which was progressive with age, and in the absence of cystic change the size of the vesicles and amount of colloid material were diminished.
The Parathyroids.—From examination of a number of specimens Dr. Donaldson finds that in old people the parathyroids appear to be free from retrogressive changes, but he cautiously requires further experience before concluding that this is the rule.
The adrenals show involutionary atrophy in common with the body as a whole, but sometimes the cortex is enlarged from excess of lipoids, usually associated with considerable atheroma, and may also show adenomas. As the increase in size of the adrenals is cortical its relation to high blood pressure, if any, is that of a remote result, namely from arteriosclerosis, and not causal as has been suggested. According to G. M. Findlay[168] the amount of lipochrome in the cells of the adrenals increases with advancing years and is accompanied by the appearance of melanin in their nuclei.
The kidneys show definite atrophy, and Councilman,[169] who has recently made a study of them in 580 persons over 60 years of age, calls the condition chronic atrophic nephropathy. The fat in the renal pelvis is more obvious than usual, the capsules are slightly thickened and occasionally but by no means always adherent, the surface finely rough and sometimes showing small cysts, but the large and irregular depressions characteristic of a granular kidney are not common. There are, however, areas of fibrosis, and the cortex and medulla are equally atrophied. Microscopically some glomeruli are fibroid, others smaller than natural. In three-fourths of his cases the renal vessels showed arteriosclerosis due to primary atrophy of the media with compensatory hypertrophy of the intima; but Councilman gives reasons for hesitation in accepting the obvious conclusion that the senile kidney is the result of the vascular change.
The prostate shows some degrees of enlargement after the age of fifty in the vast majority of men, but in only a percentage of these are there symptoms referable to it. Kenneth Walker[170] finds that the maximum size is reached at the age of 60 and that from then onwards there is a slow diminution in size; among 340 men between 80 and 90 there were 11, or 3·2 per cent, and among 92 men between 90 and 100 one only with hypertrophy of the prostate (Humphry). The causation of prostatic hypertrophy has been much discussed; that its association with arteriosclerosis (Launois[171]) is anything more than a coincidence, the two conditions being common in the later years of life, seems improbable; Walker found the two associated in 10 per cent, and he regards the change as part of a general enlargement and thickening of the peri-urethral, sub-cervical, and sub-trigonal glands, and, as the interstitial cells in the testes become fewer and degenerated, he considers that the prostatic enlargement is possibly a degeneration connected with a disturbance of the endocrine balance. Nemenow[172] argued that prostatic enlargement was due to proliferation of the interstitial cells following senile atrophy of the seminal tubules of the testes, but K. Walker found that in prostatic enlargement the interstitial cells are diminished rather than increased in number. An interesting parallel has been drawn between the involutionary changes in the mamma and the prostate, and it is probable that the same underlying factor is at work in both (Walker, Paul). Hertoghe[173] regarded some cases of prostatic hypertrophy as due to senile dysthyroidism, and recently benefit has been reported from thyroid medication and also from prostatic extract. Dr. Leonard Williams has told me of cases, as yet unpublished, showing well-marked relief of symptoms and diminution in the size of prostatic enlargement after doses of thyroid extract (½ grain once) and colloidal iodine (one dram three times) daily. The prostatic plexus of veins is often enlarged and may contain phleboliths.
The testes become smaller, softer, and commonly show some atrophy of the tubules with disappearance of the epithelial lining and thickening of the basement membrane; but the testes of old men may be free from any such change and the spermatozoa in the vesiculae seminales may be active. According to K. Walker the interstitial cells gradually diminish in number from the age of 30, but they may be present in men over 80, and Mott[174] remarks that their persistence may account for an increased and perverted sexual appetite, due to stimulation of the desire without the power to perform the sexual act.
The penis becomes smaller, often retracted, the glans harder, and the scrotum smaller.
The ovaries become shrivelled and fibrotic; the ova disappear or small cysts may form. It is difficult to find statements about the presence or absence of interstitial cells in the senile ovary. Professor Turnbull has kindly informed me that in old women an occasional cell which might be, but is not certainly, an interstitial cell is visible, and that if they are interstitial cells their number must be small and their development poor.
The uterus becomes small, its cavity round, and the cervical canal may be obliterated. The external genitals atrophy.