Fig. 4

a The fetal rat scapula and forelimb double stained with Alizarin red S and Alcian blue. (A) The control shows a fully developed scapula (s), scapular spine (ssp), humerus (h), radius (r), ulna (u), radial epiphysis (re), ulnar epiphysis (ue), carpals (c), metacarpals (mc), and phalanges (ph). (B) The fetuses maternally treated with low-dose progesterone (1.8 mg/200 g bw) shows less pronounced incomplete ossification of radial bone (re), ulnar bone (ue), humerus, and carpals. The phalanges (ph) are unossified. (C) The fetuses maternally treated with high-dose of progesterone (3.6 mg/200 g bw) show more pronounced incomplete ossification of the humerus, re, ue, and c. The phalanges are unossified. b Half of the fetal rat pelvic girdle and the hindlimb double-stained with Alizarin red S and Alcian blue. (A) The control shows fully developed ilium (il), iliac crest (il crest), pubis “anterior bone” (pu), ischium “posterior bone” (is), obturator foramen (of), femur (fe), patella (pa), tibia (t), fibula (fi), tarsus (ta), metatarsus (mt), and phalanges (ph). (B) The fetuses maternally treated with low-dose progesterone (1.8 mg/200 g bw) show incomplete ossification of metatarsals (mt) and phalanges (ph). (C) Fetuses maternally treated with high dose of progesterone (3.6 mg/200 g bw) demonstrate more pronounced incomplete ossification in the pelvic girdle parts and unossified mt and ph