HISTOMORPHOMETRIC ANALYSIS OF THE OMASUM OF SHEEP DURING DEVELOPMENT

Histomorphometric and scanning electron microscopic analyses were perf ormed on 74 embryos and fetuses and 20 sheep (early postnatal to adult age). Histologic differentiation of the omasum took place at 33 days of fetal life, with the appearance of first-order laminae. Second-, th ird-, and fourth-order laminae appeared at 39, 50, and 59 days, respec tively. Neutral mucopolysaccharides first appeared in epithelial cells at 46 days of fetal life, decreasing quantitatively until birth, befo re subsequently stabilizing in postnatal life. Acid mucopolysaccharide s, mucins, and mucoid compounds were not detected. Growth curves and f ormulas were constructed for each tissue layer. Initial tests involved multiplicative (y = axb), exponential (y = EXP a + bx!), linear (y = a bx), and polynomial models (y = a + bx + cx2 + dx3).