Detection of Thy-1+ cells in the developing thymus of the lizard, Chalcides ocellatus

The ontogenic appearance of Thy-1+ cells was studied in the thymus of the lizard, Chalcides ocellatus, by indirect immunofluorescence using a rabbit antibrain antiserum produced against surface determinants shared by both the thymus and the brain lizards. Thymic Thy-1+ cells were first detected at stage 37. They increased rapidly reaching adult numbers by stage 41. Apparently Thy-1+ cells differentiate from lymphoid precursors arriving at the thymus analage before stage 37. The results are compared to those found during the differentiation of Thy-1+ thymocyte in murine thymus and agree with former reports on the thymic development in Chalcides using rabbit antisera against adult thymocyte marker(s).