Embryonic heart malformations in Dp16 mice

A male Dp16 mouse was crossed with a female WT C57BL/6J (The Jackson Laboratory). The female was checked daily for vaginal plugs. The female was separated from the male immediately in the morning (E0.5) of visual confirmation of vaginal plugs. The pregnant mice with E9.5 or E15.5 embryos were sacrificed by CO₂ inhalation and cervical dislocation. For JAKi treatment, pregnant mice received Tofacitinib (LC Laboratories) (10 mg/kg body weight) daily via intraperitoneal injection (i.p.) starting from E6.5 to the day before embryo harvest. The yolk sac (for E9.5) or a tail snip (for E15.5) was collected for genotyping. Embryos were then fixed in 2% paraformaldehyde (PFA) at 4°C overnight. Fixed embryos were stored in 70% ethanol before being embedded in paraffin. Embedded embryos were sectioned sagittally (E9.5) or transversely (E15.5) at 7μm thickness using a LEICA RM 2155 Rotary Microtome. Serial sections were collected throughout the developing heart to assess heart malformations. Representative sections were chosen for Hematoxylin and Eosin (H&E) staining as previously described.⁸¹ (link) Histological images were then captured using the Keyence BZ-X710 All-in-One Fluorescence Microscope.