Hello,
both terms ('parvicellular' and 'parvocellular)' are used in Uberon class names, and I guess, there is none biological reason to make a difference, 'parvocellular' sounds to be the correct one, see https://en.wikipedia.org/wiki/Parvocellular_cell
UBERON:2002219 parvocellular preoptic nucleus
UBERON:0002938 parvocellular part of red nucleus
---> https://en.wikipedia.org/wiki/Parvocellular_red_nucleus)
UBERON:0002654 parvicellular part of medial dorsal nucleus
UBERON:0002937 parvicellular part of ventral anterior nucleus