DEVELOPMENT OF THE EPIDIDYMIS IN MEISHAN BOARS

The developmental process of the epididymis was investigated in Meishan boars from 1 to 364 days of age. Epididymal weight increased rapidly between 45 and 150-180 days of age. The diameter and epithelial area of the epididymal ducts greatly increased up to 105-120 days of age. At 1 day of age, the central and distal cauda already had a pseudostratified epithelium surrounded by smooth muscle. At 60-75 days of age, the central and distal caput, corpus, and proximal cauda revealed a well-developed structure of the epithelium. The proximal caput showed a tall, irregular and vacuolar epithelium at 105-120 days of age. PAS-positive contents in the lumen of the caput, corpus and cauda epididymides were first detected at 60-75, 45-60 and 1-30 days of age, respectively. Moreover, in the central and distal caput, PAS-positive granules appeared at 60-75 days of age, and increased until 105-120 days. These results suggest that the epididymis develops completely by approximately 120 days of age, though its weight increases rapidly up to 150-180 days. Thus, it appears that development of the epididymis occurs at an earlier age in Meishan boars than in European and American breeds.