This study was performed as two consecutive experiments. In the first experiment, normal avian pancreas histology of adult hens was investigated histologically and histochemically. Exocrine part was acinar in nature with their pyramidal epithelial cells. Apical porticos of the cells filled with zymogenous granules. Intermediate ducls lined up with Simple squamous epithelium were frequently encountered among the acini. In the second experiment, endocrine cells were destroyed by giving intravenously 5% wtv solution 01 alloxan (Alloxan tetrahyrate-Merck) at a dose 01 250 mgtkg body weight. The blood sugar level sharply increased up to 315.7 msY100mi at the lirst hour. and by gradual increase, reached at its highest level which is 396.8 mglOOmI at the 28th hour following alloxan administration. In non·treated. normal animals, the levels were between 18().260 rll9"100m1. The zymogenous granules disappeared at the first hour after treatment as demcostrated in the sections stained with Gomori's chrome alum haematoxylin-phloxine technique. Beta cells at the endocrine islands displayed typical degranulation together with nuclear pycnosis and kal)'OlisiS those continued unlil 48 th hour following alloxan administration. Definite cellular changes were observed in the acinar epithelia around the degenerating islands beginning at the 5th hour after the treatment. The changes continued with the appearance of basophilic granules in the acinar cell cytoplasm while they were gaining more spherical Shape. Blood sugar level dropped back to the normal level (222 mgt100m1) after 48 hours. Acinar epithelial cells were observed in the islands among the degenerated endocrine cells one week alter the treatment. This was more frequently seen at tater periods and was interpreted as a regeneration occured by transformation of acinar epithelia into beta cells