*'''Yearlings and adults''': squamous epithelium, particularly adjacent to ''margo plicatus'', glandular and antral involvement becoming more common (9, 23 in Sanchez), severe cases of ulceration can extend dorsally into squamous fundus (Sanchez) | *'''Yearlings and adults''': squamous epithelium, particularly adjacent to ''margo plicatus'', glandular and antral involvement becoming more common (9, 23 in Sanchez), severe cases of ulceration can extend dorsally into squamous fundus (Sanchez) |