Interdigitation

Interdigitation is the interlinking of biological components that resembles the fingers of two hands being locked together. It can be a naturally occurring or man-made state.

Examples

Naturally occurring interdigitation includes skull sutures that develop during periods of brain growth, and which remain thin and straight, and later develop complex fractal interdigitations that provide interlocking strength.<ref>Miura, Takashi; Perlyn, Chad A; Kinboshi, Masato; Ogihara, Naomichi; Kobayashi-Miura, Mikiko; Morriss-Kay, Gillian M; Shiota, Kohei (December 30, 2009). "Mechanism of skull suture maintenance and interdigitation". Journal of Anatomy. 215 (6): 642–655. doi:10.1111/j.1469-7580.2009.01148.x. PMC 2796787. PMID 19811566.</ref> A layer of the retina where photoreception occurs is called the interdigitation zone.<ref>Ong, Janice X.; Zandi, Roya; Fawzi, Amani A. (November 12, 2021). "Early-stage macular telangiectasia type 2 vascular abnormalities are associated with interdigitation zone disruption". PLOS ONE. 16 (11): e0259811. Bibcode:2021PLoSO..1659811O. doi:10.1371/journal.pone.0259811. PMC 8589180. PMID 34767582.</ref> Adhesion or diffusive bonding occurs when sections of polymer chains from one surface interdigitate with those of an adjacent surface. In the dermis, dermal papillae (DP) (singular papilla, diminutive of Latin papula, 'pimple') are small, nipple-like extensions of the dermis into the epidermis, also known as interdigitations. The distal convoluted tubule (DCT), a portion of kidney nephron, can be recognized by several distinct features, including lateral membrane interdigitations with neighboring cells.<ref>Verlander, Jill W. (January 30, 1998). "Normal Ultrastructure of the Kidney and Lower Urinary Tract". Toxicologic Pathology. 26 (1): 1–17. doi:10.1177/019262339802600101. PMID 9502381. S2CID 38448713 – via CrossRef.</ref>

Some hypotheses contend that crown shyness, the interdigitation of canopy branches, leads to "reciprocal pruning" of adjacent trees.<ref>"Crown Shyness: Why Some Trees Avoid Touching Leaves, Creating A Fractured Canopy". IFLScience. June 15, 2021.</ref>

Interdigitation is also found in biological research. Interdigitation fusion is a method of preparing calcium- and phosphate-loaded liposomes.<ref>"Interdigitation - an overview | ScienceDirect Topics". www.sciencedirect.com.</ref> Drugs inserted in the bilayer biomembrane may influence the lateral organization of the lipid membrane, with interdigitation of the membrane to fill volume voids.<ref>"Advances in Biomembranes and Lipid Self-Assembly | Book series | ScienceDirect.com by Elsevier". www.sciencedirect.com.</ref> A similar interdigitation process involves investigating dissipative particle dynamics (DPD) simulations by adding alcohol molecules to the bilayers of double-tail lipids.<ref>Kranenburg, Marieke; Vlaar, Martin; Smit, Berend (September 30, 2004). "Simulating Induced Interdigitation in Membranes". Biophysical Journal. 87 (3): 1596–1605. Bibcode:2004BpJ....87.1596K. doi:10.1529/biophysj.104.045005. PMC 1304565. PMID 15345539.</ref> Pressure-induced interdigitation is used to study hydrostatic pressure of bicellular dispersions containing anionic lipids.<ref>Rahmani, Ashkan; Knight, Collin; Morrow, Michael R. (November 5, 2013). "Response to Hydrostatic Pressure of Bicellar Dispersions Containing an Anionic Lipid: Pressure-Induced Interdigitation". Langmuir. 29 (44): 13481–13490. doi:10.1021/la4035694. PMID 24116385 – via CrossRef.</ref>