Quarterly Journal of Microscopical Science, Vol s3-89, 53-73, Copyright © 1948 by Company of Biologists

Variation in the Mouse Adrenal Cortex with Special Reference to the Zona Reticularis and to Brown Degeneration, Together with a Discussion of the ‘Cell Migration’ Theory

¹ Department of Zoology, University of Liverpool

1. The adrenals of two groups of mice, ranging in age from 18 days to over 1 year, were examined. One group is non-cancerous (52 males and 71 females); the other the RIII cancerous strain from which two sub-strains have been developed; (i) the CB sub-strain (23 males and 25 females); (ii) the CBB sub-strain (35 males and 40 females).

2. In the adults of both groups the parous female adrenal is bigger than the male by about 25 per cent.; the medulla is about the same size in males and females; in the female the cortex is 82.09 per cent, of the whole gland, in the male 75.64 per cent.

3. In the parous non-cancerous female, the zona reticularis is always present; in the adult male it is little developed and often absent.

4. Brown degeneration, found in the adrenal of the cancerous group, arises in the cells of the inner zona fasciculata; the subsequent formation of the typical lobules is traced. The medulla is involved in advanced conditions.

5. CB females show an advanced condition of brown degeneration, CBB females do not. Both maintain a high incidence of mammary carcinoma. Four older females of the non-cancerous group have a slight amount of brown degeneration. Cancerous males have little degeneration and non-cancerous males none.

6. The mitotic count per standard area in the cortex is given. There is no significant difference between the non-cancerous and cancerous groups or between adult males and parous females under 1 year of age. Over 1 year there is an indication that the amount of cell division falls off, although in the female mitoses are still found up to 456 days. Mitoses occur all through the zona glomerulosa with the majority towards the inner border.

7. The histological evidence is, on the whole, in favour of the ‘cell-migration’ theory (the centripetal movement of cortical cells with replenishment from the periphery and destruction at the medullary border). It is suggested that brown degeneration is a variation of the way in which cortical cells normally degenerate; but the causative factor is not known; it has no direct correlation with mammary cancer, and its occurrence as characteristic of certain cancerous strains may only be coincidental.