Amoeboid origin

My hypothesis otherwise remains what it was in 1993 - the epithelial component originated from an epithelial animal and the amoeboid component originated from an amoeboid animal equipped with a protocnidocysts, and possibly already living as an intracellular parasite on the epithelial animal during some stage of its life cycle. One or another device for cell fusion would have to be invoked to explain how an amoeba and an epithelium... 

Ling, E. A. and Wong, W. C. The origin and nature of ramified and amoeboid microglia an historical review and current concepts. Glia 7 84-92,1993. 

The 1980 view assumed that the prokaryote-to-eukaryote transition occurred via gradualist mechanisms such as point mutation and hence did not involve symbiosis at all (van Valen and Maiorana 1980 Doolittle 1980) and culminated with a cell that possessed a nucleus, but lacked mitochondria. This is what Doolittle (1998) has called the standard model . In this view, mitochondria are interpreted as a small tack-on to, and mechanistically unrelated to, the process that made eukaryotic cells nucleated and complex (Cavalier-Smith 2002). In the standard model, mitochondria (and chloro-plasts) are descended from endosymbionts, but the nuts-and-bolts of the prokaryote-to-eukaryote transition (the origin of eukaryote-specific traits) was seen as having occurred independently from, and prior to, the origin of mitochondria. The paper by van Valen and Maiorana (1980) expresses this view in clear physiological terms the host was assumed to be an amoeboid, anaerobic, fermenting cell related to archaebacteria, the advantage of the mitochondrial endosymbiont was to supply ATP. 

First we review CAIs and their forsterite-rich accretionary rims, then amoeboid olivine inclusions and aluminum-rich chondrules, which are intermediate in composition between CAIs and chondrules, and finally matrix, which is a complex mixture of many ingredients. Although chondrules are volumetrically more important, we start with CAIs as these formed first and their origins are better constrained by chemical and isotopic data. Chemical and isotopic variations in chondrules are much more modest than those in CAIs but there are enough related features and components with intermediate compositions to suggest that chondrules cannot be understood in isolation from CAIs and other components. 

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