The Effects of Adrenalectomy in the Ovine Fetus

ABSTRACT The effects of fetal lamb adrenalectomy (Adx) on brain function, metabolism and lung development were studied in seven experiments. Thirty‐two fetal adrenalectomies were performed at gestational ages ranging from 112 to 116 days. “Indwelling” catheters were placed in maternal and fetal circulation for chronic sampling in 15 experiments. All catheterized fetuses were spontaneously aborted within 25 days postsurgery. Of 17 noncatheterized fetuses, seven (five twins and two singletons) survived to near term (136‐144 days), at which time they were studied for the effects of Adx. Maternal plasma Cortisol concentration did not differ significantly between Adx and C (control) (Adx: 16.54 ± 2.54 μg%; C: 18.1 ± 2.65 μg%). Fetal plasma cortisol concentrations were significantly lower in Adx than in C fetuses (Adx: 1.56 μg% ± 0.35 μg%; C: 9.6 ± 2.43 μg%; p < 0.025). In mitogen tests, lymphocytes from C fetuses showed responses greater in magnitude than their Adx twins. Five of the seven Adx fetuses showed immature EEG tracing in comparison with the age‐matched control (twin C or singleton C). Quantitative measurement by light microscopy revealed significantly fewer giant alveolar or type II cells in four of six Adx fetuses, as opposed to the age‐matched twin C or singleton C (p < 0.01). The relative immaturity of the brain function and lung development in the third trimester Adx fetuses probably indicates that fetal adrenal glands are important in the development of these vital organs.