The effects of minoxidil on the development of the chick embryo

Abstract

The effects of minoxidil were studied on chick embryos of 24 and 48 hours of incubation. Minoxidil (3%) was injected into the air sacs of the eggs at doses of 20, 30, 40, and 50 ul per egg. The controls received 100 ul of physiological saline. All the embryos, including controls, were examined at day 13. The total number of eggs used in this study was 300. At 24 hours incubation, the percentage of survival ranged from 87 to 21 as the dosages of minoxidil were increased from 20 ul to 50 ul per egg (controls = 87%). The survival of the embryos ranged from 79% to 9% after the 48-hour treatment with the similar dosages of minoxidil utilized for the 24-hour group (controls = 83%. A low incidence of gross malformations such as twisted limbs, abnormal beak, short neck and everted viscera were observed; however, the increased incidence was not statistically significant when compared to controls. Body hemorrhage and edema were of high occurence among the treated embryos. These effects are probably secondary to the known pharmacological effects of minoxidil. The frequency and types of gross malformations did not very much in the 24 or 48-hour treated groups. The results of this study indicate that minoxidil is embryolethal at higher doses and causes body hemorrhage and edema during chick embryogenesis.