[2] Thymic nurse cells express both MHC Class I and II antigens,[3][4] and are found in the cortico-medullary junction in addition to the cortex of the thymus.
Hendrix et al. found in their study that one-fourth of the nurse cells isolated from mice were double-positives for K5 and K8, while the rest of them were positive only for K8.
[2] The enclosed thymocytes have been found to remain intact and retain both metabolic and mitotic activities despite lacking any contact with the extracellular environment.
Also, almost 90% of all thymocytes extracted from the female TNCs were found to be double positives (CD4+CD8+), whereas no such phenotype was present within the male thymic nurse cells.
Thus, since not all thymocytes internalized by TNCs went through apoptotic pathways, this was used to conclude that thymic nurse cells are involved in MHC restriction process.
The formation of finger-like projections has been found to facilitate this uptake; which also requires the participation of membrane and cytoskeleton proteins of TECs and thymocytes.
This suggests that metabolic activity of epithelial thymocyte complex is essential for the release of TNC-T. TNC-T are functionally mature than those external to TNC (ET).
[15] Based on the observation that TNC harbor functionally mature population of TNC-T [12][13][14][15] and the electronmicroscopic studies suggesting that TNCs are localized in close proximity of blood capillaries in both cortex and cortico-medullary region of thymus, Vakharia & Mitchison have hypothesized that TNC-T are potential thymus emigrant cells.