part of part of in taxon results in morphogenesis of developmental growth spongiotrophoblast layer development spongiotrophoblast layer developmental growth The increase in size or mass of the spongiotrophoblast layer of the placenta where the increase in size or mass contributes to the progression of that layer over time from its formation to its mature state. tb 2010-01-08T12:10:44Z GO:0090214 Rodentia spongiotrophoblast layer