Jami Sagar Prusti
BACKGROUND The cortical portion of the suprarenal gland (SRG) develops rapidly and is relatively more advanced during the first half of pregnancy than the other abdominal or thoracic organs. The cortex of the foetal adrenal gland is much thicker than that of the adult gland and consists of at least two histologically distinct layers: the outer definitive zone and the inner provisional zone. The inner, provisional cortex continues to grow as long as the foetus remains in the uterus, but immediately after delivery it begins to retrogress. No other organ in the body except the uterus and mammary gland grows in this manner. MATERIALS AND METHODS In view of the interesting changes in the histology of the gland during its development, this study was undertaken to study its histogenesis in 50 human foetuses of different age groups ranging from 12-40 wks. using routine histological stain haematoxylin and eosin and to observe with the advancing gestational age, the changes in the cortex of the gland, the ratio of the permanent cortex to foetal cortex, the differentiation of permanent cortex into its three zones and do histometry to measure the thickness of capsule, superficial and deep cortices. Very less literature is available regarding the histogenesis of the SRG. The present study is an attempt to add data to the existing literature. RESULTS The capsule was identifiable by 12 wks. and it increased in thickness with increasing gestational age. Two regions in the cortex were identified i.e. the adult cortex with small basophilic cells that was subcapsular in position, and foetal cortex with large eosinophilic cells towards medulla. Micrometry was done and in the early weeks, the adult cortex seems to occupy 1/4th of the cortex and foetal cortex the remaining 3/4th; later by 24 wks., the foetal cortex became bulkier and measures 4/5th of the cortex with the adult cortex occupying only 1/5th. CONCLUSION The large size of the SRG results from the extensive size of the foetal cortex, which produces steroid precursors that are used by the placenta for the synthesis of oestrogen.
