The thymus is pale and distinctly lobulated. It is much larger in the
calf than in the foal, weighing at five or six weeks about 15 to 25
ounces (ca. 425 to 600 grams). The cervical part is specially large,
thick, and compact; it extends to the thyroid gland. It undergoes
atrophy slowly and remnants of the thoracic part often remain even in
advanced age.