THE DEVELOPMENT OF THE ADRENAL-GLAND ZONA GLOMERULOSA IN THE RAT - A MORPHOLOGICAL, IMMUNOHISTOCHEMICAL AND BIOCHEMICAL-STUDY

We have studied the development of the adrenal gland in the rat compri sing the ages ranging from 0 to 90 days after birth. The weight of the animals and that of the adrenal glands demonstrated a linear growth w ith time until 75 days, both in males and females. The area of the zon a glomerulosa (ZG) increased in size from birth until approximate to 4 0 days of age. After that, growth had a much smaller slope (females, r = 0.84, P < 0.001; males, r = 0.81, P < 0.001). Aldosterone secretion had a marked increase until 20 days of age and thereafter demonstrate d a tendency for a decrease (females, r = - 0.19, P < 0.02; males r = - 0.26, P < 0.001). Plasma renin activity followed a trend parallel to that of aldosterone. The steroid precursor 18-OH-deoxycorticosterone (18-OH-DOC) demonstrated a different course as it increased progressiv ely with age especially in the females (females, r = 0.57, P < 0.001; males, r = 0.40, P < 0.001). The expression of the enzyme 3-beta-hydro xysteroid dehydrogenase (3-beta-HSD) was also studied by immunohistoch emistry and it was shown to be very low at birth and starting to incre ase by 10 days of age. After 30/40 days of age the amount of this enzy me existing in the ZG was comparable with that of the outer zona fasci culata (ZF). We conclude that the development of the ZG in the rat has particularities that make it different from that of the rest of the c ortex. (C) 1998 Elsevier Science Ireland Ltd. All rights reserved.