Dictionary

Some new terms from Chapter 2- part 2 lecture notes

• Hassall's corpuscles - cells of varied types, notably of epithelial tissue, but also interdigitating dendritic cells, myoid cells, and other types present in the thymic medulla. (Mikušová et al., 2017). They were originally supposed in humans to be key in apoptotic thymocyte removal and thymocyte maturation, however it was later proposed that in fact they are instrumental in the process contributing to the development of CD4+CD25+ regulatory T cells. (Watanabe et al., 2005).

The medulla of the thymus is the home of Hassall's corpuscles.

Picture here is a Hassell's corpuscle. Photo credit: Drvasilerus. Accessed from Wikimedia.

• Extravasation - According to the National Cancer Institute, there are two related definitions given, both which refer to something leaving a blood vessel as the name might imply. In one context, the substance would be either blood, lymph, or even a medication used to combat cancer that is leaking into the tissue surrounding a particular blood vessel. Or it could be referring to metastasis or inflammation induced cell migration from the blood vessel.

The extravasation of the cancerous cells resulted in widespread metastasis in her breast tissue.

In this example shown above, extravasation is a positive thing as neutrophils have been dispatched to combat infection. Photo credit: Dr. Mario Schubert. Accessed from Wikimedia.

A new term from Chapter - part 1 lecture notes

• Opsonize- to identify and attack pathogens in order to conduct phagocytosis. (Thau et al., 2024).

C3b, which results from the hydrolysis of factor C3, is able to opsonize pathogens and catalyze phagocytosis.

This diagram demonstrates how C3b is made. Photo credit: NIH Publication No. 03–5423, September 2003 (modifications: September 4, 2006) (SVG 1 December 2015). Accessed from Wikipedia.

References:

Watanabe N, Wang YH, Lee HK, Ito T, Wang YH, Cao W, Liu YJ. Hassall's corpuscles instruct dendritic cells to induce CD4+CD25+ regulatory T cells in human thymus. Nature. 2005 Aug 25;436(7054):1181-5. doi: 10.1038/nature03886. PMID: 16121185

Mikušová, Renáta, et al. “What Do We Know about the Structure of Human Thymic Hassall’s Corpuscles? A Histochemical, Immunohistochemical, and Electron Microscopic Study.” Annals of Anatomy - Anatomischer Anzeiger, vol. 211, May 2017, pp. 140–148, https://doi.org/10.1016/j.aanat.2017.02.006.

National Cancer Institute. “NCI Dictionary of Cancer Terms - National Cancer Institute.” Www.cancer.gov, 2 Feb. 2011, www.cancer.gov/publications/dictionaries/cancer-terms/def/extravasation.

Thau L, Asuka E, Mahajan K. Physiology, Opsonization. [Updated 2023 May 1]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK534215/