author(s)
Dr. Iman Moussa Khaleel and Ali Ahmad Mohammad Salih

abstract
The present work was carried out on 8 adult healthy indigenous gazelle and sheep (4 gazelle and 4 sheep) to study the histomorphological and histochemical features of thyroid gland in these two animals and to compare between them. The present findings showed that the histological structure of the thyroid gland in both sheep and gazelle was similar and appeared covered by a connective tissue capsule which send trabeculae that divide the glandular parenchyma into irregular lobules which made up of aggregation of a various shape and size of follicles that lined by a predominantly of simple cuboidal and simple columnar epithelium in gazelle, whereas in sheep lined by simple cuboidal to simple squamous epithelium. The para follicular cells were present inter epithelium and inter follicular, myoepithelial cells were also present in both thyroid gazelle and sheep. The colloid material found in the follicular lumen was PAS positive. The isthmus was glandular in both studied animals. The histomorphometrical analysis revealed there were a significant importance at p<0.05 between left and right lobes with the isthmus in both sheep and gazelle. There was a significant importance at p<0.05 in the height of the epithelium between sheep and gazelle.