Alligator mandibular development during long term organ culture

Abstract

The development of the first branchial (mandibular) arch of the American alligator (Alligator mississippiensis) is studied in organ culture for the first time. There is extensive mandibular morphogenesis in vitro and the pattern of the differentiated elements, bones, muscles, and cartilage, is comparable to that found during normal development in ovo. In addition, we observe the development of paired lingual swellings and the formation of a small tongue consisting of fibrous, lipid containing, and muscular tissues, as found in the normal tongue. Several culture variables are examined: (a) although alligator embryos normally develop at 30°C, we successfully culture the mandibular rudiments with good short term (3 wk) results at 37°CC; (b) at 30° C, we are able to culture arches for long term periods of 6 wk; (c) the mandibular arches develop well in both serum containing medium and in a chemically defined medium free from added hormones. The reptilian mandibular arches exhibit excellent, patterned, development and may have less stringent culture requirements than their avian and mammalian counterparts.