Prolonged Survival of Insect Tissues in Vitro1

Abstract

The epidermis of insects has long served the student of growth as excellent material for the solution of morphogenetic problems. Unfortunately, as others have recently pointed out (Schmidt and Williams, 1953; Goodchild, 1954; Grace, 1954) no one has succeeded in culturing insect epidermis (or any other insect tissues for that matter) to the degree that vertebrate tissues have been cultured. Insect blood has often been used as a culture medium but it is surprising that it (with or without cells) is an unsatisfactory medium for all insect tissues save the spermatocytes and ovaries (Schmidt and Williams, 1953; W. H. Telfer, unpublished observations). Thus Goodchild (1954) has described changes which appear to be degenerative in fragments of Rhodnius epidermis maintained in hanging drops of Rhodnius blood for 10 to 14 days. Similarly in our laboratory we have found that although immature spermatocytes of the cynthia moth, Samia cynthia (Drury), and the polyphemus moth, Antheraea polyphemus (Cram.), undergo spermatogenesis in the blood of developing adult silkworms (to which phenylthiourea and streptomycin were added), fragments of pupal wing epidermis underwent prompt degenerative changes similar to those described by Goodchild: they tended to form rounded granular masses and the nuclei became indistinct within a few days. After five to six days all noticeable changes ceased. Cultures maintained in Ringer‗s solution (Ephrussi and Beadle, 1936) lasted somewhat longer but degenerated after about 10 days. However, by using a chemically defined medium (TC 199) originating in the laboratories of Morgan, Morton, and Parker (1950) we have maintained epidermis from the pupal wing and antenna, alive in vitro for between 20 and 35 days.