Question

H. V. Wilson worked with sponges to gain some insight into exactly what was responsible for holding adjacent cells together. He exposed two species of differently pigmented sponges to a chemical that disrupted the cell—cell interaction (cell junctions), and the cells of the sponges dissociated. Wilson then mixed the cells of the two species and removed the chemical that caused the cells to dissociate. Wilson found that the sponges reassembled into two separate species. The cells from one species did not interact or form associations with the cells of the other species. How do you explain the results of Wilson's experiments?

Answer 1

Probably, molecules responsible for holding cells together (cell-cell adhesion) are specific for species, meaning that each species has its own molecules that don’t act on other species’ cells.

The term used for this property is species-specific cell recognition and most likely involved molecule is proteoglycan-like complex also called aggregation factor.

Even though, sponges are simple and at low phylogenetic position, their histocompatibility systems (compatibility of tissues) are at high level.