Developmental changes in the histological structure of the testes, and testosterone profiles in male guinea fowls (Numida meleagris)

- Testicular morphometric parameters in male guinea fowls stabilized between 20 and 24 WOA.
- Peripheral testosterone (T) concentrations during sexual development in male guinea fowl showed two phases of T secretion.
- Peripheral T levels in these birds may be implicated in the histological changes in the testes and spermatogenesis.

Owing to the paucity of information on the reproductive biology of guinea fowls, a study involving a total of 66 males was conducted, and documented the developmental changes in histological structure of the testes of guinea cocks from hatching until adulthood. Changes in testosterone synthesis during sexual development were also determined. Age-related changes were analysed using univariate analysis for completely randomised design and means separated using Tukey's test/Kruskal-Wallis test and medians separated by Mann-Whitney U test. Total germ cell population per testis and testicular histological morphometric parameters increased significantly (p < 0.0001) from 12 weeks of age (WOA), and stabilized between 20 and 24 WOA. Peripheral testosterone concentrations increased gradually from 4 WOA, and peaked at 20 WOA. Correlations among all the testicular morphometric parameters were positive and highly significant (p < 0.01). Similarly, significant (p < 0.05) positive correlations existed between testicular weight and testicular sperm production, tubular diameter, Sertoli cell population, tubular length and peripheral testosterone concentration. Testicular sperm production was positively correlated with meiotic index (p < 0.01) and round spermatids population (p < 0.05). The correlations between peripheral testosterone concentrations, tubular diameter and Sertoli efficiency were also significant (p < 0.05) and positive. Testicular morphometric parameters stabilized between 20 and 24 WOA, while peripheral testosterone concentrations showed two patterns of secretion, initial and final phases of increasing and decreasing testosterone secretions, respectively, and may be implicated in the development of histological structures of the testes and spermatogenesis.