Editing Pathogen transmission (section)

===Vertical transmission===

[[Vertical transmission (symbiont)|Vertical transmission]] refers to acquisition of symbionts from parents (usually mothers). Vertical transmission can be intracellular (e.g. transovarial), or extracellular (for example through post-embryonic contact between parents and offspring). Both intracellular and extracellular vertical transmission can be considered a form of non-genetic [[Hologenome theory of evolution|inheritance]] or [[maternal effect|parental effect]]. It has been argued that most organisms experience some form of vertical transmission of symbionts.<ref>{{cite journal | vauthors = Funkhouser LJ, Bordenstein SR | title = Mom knows best: the universality of maternal microbial transmission | journal = PLOS Biology | volume = 11 | issue = 8 | pages = e1001631 | date = 2013 | pmid = 23976878 | pmc = 3747981 | doi = 10.1371/journal.pbio.1001631 | doi-access = free }}</ref> Canonical examples of vertically transmitted symbionts include the nutritional symbiont [[Buchnera (bacterium)|Buchnera]] in aphids (transovarially transmitted intracellular symbiont) and some components of the [[Gut flora#Acquisition of gut flora in human infants|human microbiota]] (transmitted during passage of infants through the birth canal and also through breastfeeding).{{cn|date=June 2021}}