Growth of Japanese Quail Testes in Relation to Age: Morphological and Immunohistochemical Observation

Objective: The purpose of this research was to observe the age-related growth and histomorphological changes in Japanese quail testes from post-hatching to sexual maturity as well as spermatogenesis.Materials and Methods: After collection, the testes weight, length, width, and index analysis were performed, and histomorphological, histological and immunohistochemical observations were conducted using hematoxylin-eosin, PAS-hematoxylin, and anti-Hsc70t staining, respectively at different ages.Results: The weight of the testes increased gradually with age and reached a peak at 70 days. The length and width of the testes were maximal at 70 days. The testis index was positively correlated with age and body weight (BW) toward sexual maturity. Histologically, at 15 days of age, the seminiferous tubules (STs) remained in immature state with undifferentiated spermatogenic cells of only one to two layers of epithelial cells. At 28 days, the spermatogenic cells were differentiated from spermatogonia to spermatocytes. At 42 days, remarkable enlargement of STs with a series of spermatogenic cell development up to the round spermatids and Leydig cells in the interstitial region. Finally, at 70 days, extremely enlarged STs containing all stages of spermatogenic cells. The diameter and height of STs were maximal at 70 days than that of 42 days of age. A strong Hsc 70t immunoreaction was found in the round to elongated spermatids/spermatozoa near to the lumen of STs, clearly indicating well-characterized spermatogenesis in quail testis at 70 days of age.Conclusion: The findings may contribute to our understanding of quail’s spermatology and provide basic knowledge for reproductive toxicology, physiology and pathology studies.