File:Bardeen1906-plate02.jpg

Plate II. Four sections through the base of the lower limb Embryo 7 to 33 mm

Four sections through the base of the posterior limb to illustrate different stages in the development of the nerves and musculature.

FIG. 1. Section passing through the right limb-bud in embryo II, length 7 mm., age 26 days. The tips of the neighboring myotomes do not extend into the mass of tissue of which the limb-buds are composed and in which as yet no specific differentiation is visible. 33 diam.

FIG. 2. Secton passing transversely through the base of the right limb- bud of embryo CIX, length 11 mm., age about five weeks. At the center of the limb-bud the acetabular region of the skeleton appears as a condensed mass of tissue. About this the femoral, obturator, and sciatic nerves may be seen extending into the limb bud. Myogenous tissue is fairly well marked near the femoral and sciatic nerves. 25 diam.

FIG. 3. Transverse section passing through the acetabular region of left leg of embryo CXLIV, length 14 mm., age about five and" one-half weeks. The femoral, obturator, gluteal, and sciatic nerves may be seen extending into the limb bud, and in the vicinity of these nerves the anlages of the iliopsoas, pectineus, adductor, hamstring, and gluteal muscles. 25 diam.

FIG. 4. Transverse section passing through the acetabular region of em- bryo CXLV, length 33 mm., age about two months. The femoral, obturator, inferior gluteal, and sciatic nerves may be seen entering the limb. The chief fasciculi of the iliopsoas, pectineus, adductor, and gluteus maximus muscles are separated by an amount of connective tissue relatively greater than in the adult. 10 diam.