Morphometric study of the human suprarenal gland in the first postnatal year.

The aim of present, study was to describe adrenal volume, volumes of adrenocortical zones, and stroma volume in 40 adrenals obtained from children between 1st and 370th day during autopsy. The postnatal decrease in adrenal volume was caused mainly by rapid fall of fetal zone (FZ) volume (from 70 to 3% of total adrenal volume), that can be divided into two phases: rapid phase (from birth to the end of the second week) and a slow phase from the 3rd week on. Involution was accompanied by increase of zona glomerulosa (ZG) (from 10 to 25% of total adrenal volume), zona fasciculata ZF (from 10 to 38%) and zona reticularis (ZR), volume (from 1 to 23%). During the whole investigated period the volume of medulla remained constant. The volume fraction of stroma (connective tissue and blood vessels) was highest at the beginning of the first postnatal week and then decreased rapidly at the end of the 2nd week, with the most pronounced changes in the fetal zone and medulla. Performed present stereological study confirms opinion that hemorrhagic mechanisms are involved in the involution process of the human fetal zone.