Eight terpenoid derivatives with juvenile hormone activity were tested for teratogenicity. Three of the derivatives were teratogenic when administered to mice as a single intraperitoneal injection of 1 mg/gm on either day 9 or day 10 of pregnancy. However, intubation at 5 mg/gm of the two most teratogenic derivatives resulted in one of the derivatives marginally increasing the incidence of abnormal embryos above peanut oil-intubated controls; the other intubated derivative was without adverse affect. Of the remaining five compounds, two with high juvenile hormone activity were without teratogenic effect when injected at 1 mg/gm. Since teratogenic effects were observed only at a dose above likely exposure levels and by a route of administration not possible in the environment, support is provided for the potential use of terpenoid derivatives in the control of insect pests.

Many, but not all, embryonic mesenchymes were found to be inductively active when combined with kidney mesenchyme. Tissues undergoing ossification are particularly active. There is variation in the time-course of appearance of tubules in kidney mesencyme: 2 days for jaw, 4 days for developing bone, and 5–6 days for salivary mesenchyme or somite.