Quick Facts
A suprarenal capsule encloses the suprarenal gland.
Structure and/or Key Feature(s)
The capsule of the suprarenal gland is composed of a single layer of thick fibrous tissue which envelopes the whole gland, providing numerous supportive and protective features. It is derived from mesenchymal cells (Vidal et al, 2016).
Anatomical Relations
The capsule of the suprarenal gland is covered with perirenal fat, which is enclosed within the renal fascia. These capsulated glands lie on the anterior superomedial aspect of the kidneys. The capsule of the suprarenal gland is separated from the kidney via a thin fibrous layer along the inferior aspect of the capsule.
Superior, middle, and inferior suprarenal arteries approach and branch out over the capsule. They form a subcapsular meshwork of vessels which provide an arterial supply to the gland.
Function
While the capsule of the suprarenal gland offers structural and protective support to the glands, it also houses a dense arterial plexus within it. Projections of the capsule, called trabeculae, penetrate throughout the gland, and provide passage of the long sinusoids of the arterial plexus deep into gland tissue, providing a plentiful blood supply. The glands require this dense bloody supply due to the production of important hormones.
Another important role of the capsule is to aid the upkeep and repair of the cells throughout the gland. There is a reserve pool of progenitor stem cells within the capsule. These can differentiate to restore senescent cells, and to maintain or expand the three different zones of the cortex (Pihlajoki et al, 2015).
References
Pihlajoki, M., Dörner, J., Cochran, R. S., Heikinheimo, M. & Wilson, D. B. (2015) Adrenocortical zonation, renewal, and remodeling. Frontiers in endocrinology, 6, 27-27.
Vidal, V., Sacco, S., Rocha, A. S., da Silva, F., Panzolini, C., Dumontet, T., Doan, T. M., Shan, J., Rak-Raszewska, A., Bird, T., Vainio, S., Martinez, A. & Schedl, A. (2016) The adrenal capsule is a signaling center controlling cell renewal and zonation through Rspo3. Genes Dev, 30(12), 1389-94.
