The mesohyl, formerly known as mesenchyme, is the gelatinous matrix within a sponge. The mesohyl resembles a type of connective tissue and contains several amoeboid cells such as amebocytes, as well as fibrils and skeletal elements. For hundreds of years, it has been largely accepted that sponges lack true tissue, but it is currently debated as to whether mesohyl and pinacoderm layers are in fact tissues.

References

• Lytle, Charles F., and John R Meyer. General Zoology Laboratory Guide, Fourteenth Edition. New York: McGraw-Hill, 2005.