Pig F2L

DEVELOPMENT OF THE GUT

F2,F3: Mesentery. Returning limb of midgut loop.

F1-F6: Gut loop extending caudally "up" into sacral region, attached by a dorsal mesentery. Separation of dorsal aorta.

F2: L umbilical vein, both umbilical arteries. Allantois.

DEVELOPMENT OF THE NERVOUS SYSTEM

F2: Spinal cord has enlarged ventral horns (motor neurons).

DEVELOPMENT OF THE MUSCULOSKELETAL SYSTEM

F1,F2: Caudal limit of forelimb. Broad extensor surface. Dense mesenchyme of hindlimb. Note lumbar somites, somitocoeles.