Defects in capillary formation in both CAGp- and Tie-2p-ephrin-B2 Tg mice.

(A, B) Expression of ephrin-B2 in capillary-sized vessels in the P14 neonatal mouse. Before lectin staining (brown color), X-gal staining was performed. X-gal staining of ephrin-B2^LacZ/+ mice indicates that ephrin-B2 (blue color) was detected sporadically in capillary-sized vessels (arrows in B), while ephrin-B2 was strongly expressed in the large-sized arterial vessels (arrows in A). Arrowheads in panel B indicate ephrin-B2⁻ ECs in capillary-sized vessels. Comparison of microvessel morphology of the ear in lectin-stained whole mounts of ear skin (C-E). A marked decrease in capillary-sized vessels was seen in CAGp-ephrin-B2 Tg mice and Tie-2p-ephrin-B2 Tg mice compared to wild-type littermates. X-gal staining indicates that ephrin-B2 (blue color) was expressed in arteries, veins, and capillary-sized vessels in Tie-2p-ephrin-B2 Tg mice (E). A model of capillary formation is shown in panel F. All bars indicate 50 μm. In lines 12 and 21, the total numbers of surviving mice were counted from 3 independent crosses between F1 Tg/+ male and Tg/+ female mice.