ESPE Abstracts

Background: We previously found that mast cells are present in the human adult adrenal gland with a possible role in the regulation of aldosterone secretion in both physiological conditions and aldosterone-producing adrenocortical adenomas responsible for primary hyperaldosteronism.

Objective and Hypotheses: The aim of the present study was to investigate the presence of mast cells in the human fetal adrenal gland, and to provide arguments in favor of their implication in its development.

Method: Paraffin-embedded human fetal adrenal samples were studied at 13 different stages of development from 16 weeks of gestation (WG) to the term.

Results: Immunopositive cells for the mast cell marker tryptase were firstly detected at 20 WG with a peak of density at 28–31 WG. Double immunostaining with antibodies against the steroidogenic enzymes 3βHSD, characterizing the definitive and transition zones, and 17 α-hydroxylase (17-OH; CYP17), characterizing the transition and fetal zones, revealed that mast cells are mainly located in the vicinity of steroidogenic cells in the subcapsular definitive zone. There was no correlation, in term of timing of expression, with either 17-OH, which was present at all studied stages, or 3βHSD firstly detected quite earlier at 18 WG.

Conclusion: We demonstrated for the first time that mast cells are present in the human fetal adrenal gland from the second trimester of pregnancy. However, no clear evidence of relationship was found with the kinetics of steroidogenic enzymes expression. Further studies need to be performed, such as investigation of CYP11B2 expression, to assess an eventual role of mast cells in aldosterone production and to better understand the role of these intra-adrenal mast cells in the fetal development.