<![CDATA[Anti-aging skincare products are widely used because of their potential to reduce visible signs of skin aging. Argireline (acetyl hexapeptide-8) and Matrixyl-related peptides are commonly incorporated as bioactive ingredients in cosmetic formulations. Despite their widespread topical use, information regarding their potential developmental toxicity remains limited. This study aimed to investigate the potential teratogenic effects of argireline and matrixyl using an in ovo chick embryo model (Gallus gallus gallus). Fertilized eggs were incubated for 68 h and subsequently exposed to different concentrations of argireline (1%, 5%, and 10%) or matrixyl (5%, 10%, and 20%) through fenestration of the vitelline membrane. After a total incubation period of 116 h, corresponding approximately to Hamburger–Hamilton stage 25, the embryos were fixed in 10% neutral-buffered formalin (NBF), dehydrated in methanol, and examined using a stereomicroscope. Exposure to 5% and 10% argireline resulted in a significant reduction in mesencephalon size, accompanied by morphological indications suggestive of microphthalmia at both concentrations. Embryos exposed to 1% argireline exhibited mild enlargement of the brain and eye regions; however, the biological significance of this response requires further investigation. In contrast, embryos treated with matrixyl showed no apparent morphological abnormalities under the experimental conditions used. These findings indicate that argireline may induce concentration-dependent developmental alterations at higher concentrations and highlight the potential utility of the chick embryo model for preliminary screening of the developmental toxicity of cosmetic peptides. Further studies incorporating larger sample sizes, additional developmental endpoints, and complementary toxicological approaches are required to confirm these findings.]]>
