Growth of Mammary Gland in the Rhesus Monkey. ∗

Abstract

Thirty-one females and 3 male rhesus monkeys of a wide range of body weights were used. All were kept under observation for at least 4 months. No animal dying from a protracted illness or used for other experimental purposes was included. The area of the mammary tissue was measured and compared with the weight of the kidneys and ovaries. Since the mammary tissue in the macaque grows in length and width rather than in thickness, a measure of the area of the gland gives an index of the change in size.

In 12 animals the skin surrounding the mammary tissue was tatooed, a pattern was traced, the gland with the skin was cut along the tatoo marks, dissected free of muscle, and stretched on a flat piece of cork the exact size of the pattern. The skin from the center of the tissue was removed, leaving the gland surrounded by a frame of skin. After fixation and staining the size of the gland was compared to the size of the pattern. An average shrinkage of 7% was found. Since all glands were treated in the same way this shrinkage would not affect the comparison.

After the tissue was mounted a tracing of the gland was made. The tracing was taken as if a wheel of a half-inch diameter was run about the periphery, the pencil only marking the deeper indentations. The average difference between the areas of the right and left glands from the same animal was not significant. Where only one gland had been preserved its area was multiplied by 2. In order to determine the error in the method, 2 tracings were made from 10 glands and 2 readings with the planimeter were made from every tracing of all the glands.