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

Post-hatch changes in the histological structure of the oviduct and associated 17β-estradiol profiles in guinea hens (Numida meleagris)

There is a limited data available on the biology of guinea fowls. The objective of this study was to document post-hatch histological and stereological changes in the oviducts of 56 guinea hens and associated 17β-estradiol profiles until 32 wk of age and to explore changes in the oviducal mucosal fold as an index of oviducal growth. Mucosal folds in all regions of the oviduct increased significantly (P < 0.0001) from 4 to 28 wk of age. Concentrations of plasma 17β-estradiol increased from 20 to 28 wk of age, when it stabilized. Mucosal folds in the oviducts of sexually active hens were highest in the uterine region and lowest in the infundibular lip. Intercorrelations among 17β-estradiol concentration, height of mucosal folds, and oviducal weight were strong and positive in these birds. Most of the oviduct epithelium consisted of pseudostratified columnar ciliated epithelium. Both the height of oviducal folds and peripheral estradiol concentrations increased significantly from 20 to 28 wk of age, which confirms the role of estradiol in oviducal growth in the avian species. The height of oviducal mucosal folds appears to be a good measure of oviducal growth.

Photoperiodic Modulation in Immune and Reproductive Systems in Japanese Quails (Coturnix japonica): A Morphometric Perspective

The present study was designed to elucidate a relationship between lymphoid organs and reproductive activity in male Japanese quails (Coturnix japonica) bred in a temperate region of Pakistan (30.3753° N, 69.3451° E) in response to photoperiodic changes. The research focused primarily on the relative morphological changes in primary (thymus and bursa of Fabricius) and secondary (spleen) lymphoid organs with respect to seasonal variations in the histomorphometry of testicular tissue. For this purpose, a comparable number of clinically healthy Japanese quails were exsanguinated during active (April–May), regressive (September–October) and inactive (January–February) reproductive phases. Following an extensive gross measurement of lymphoid and reproductive organs, a histomorphometric analysis was performed on sampled tissues by employing ImageJ^® software. Blood was collected for hormonal and leukocytic analysis. One-way ANOVA was used for statistical comparison. Testes had the highest parenchymal development in the active phase (80.66 ± 21.22 µm) and the lowest in the inactive phase (27.80 ± 7.22 µm). Conversely, a percentage change was evident in the sizes of primary (bursa: 61.5%, thymus: 46.9%) and secondary (spleen: 23.9%) lymphoid organs during inactive and active reproductive phases. This study demonstrated that a physiological trade-off is imperative between immune and reproductive systems for optimum survivability and reproductive performance.

Postembryonic developmental changes in ovarian histology and associated 17β-oestradiol and progesterone profiles in guinea hens (Numida meleagris)

There is a paucity of information on the reproductive biology of guinea hens. A study was conducted to document postembryonic developmental changes in the ovarian histology and associated progesterone and 17β-oestradiol profiles until 32 wk of age (WOA). Highly significant increases (P < 0.001) were noticed in oocyte and follicular diameters beyond 16 WOA. Other ovarian follicular morphometric traits showed inconsistent increases until 16 WOA. The first phase of yolk deposition occurred between hatching and 20 WOA, the second phase between 20 and 26 WOA, and the third and final phase between 27 and 28 WOA. Peripheral 17β-oestradiol concentrations increased from 20 WOA until it peaked at 28 WOA, whereas peripheral progesterone concentrations fluctuated considerably during sexual development. Both oestradiol and progesterone concentrations were negatively and moderately correlated (P < 0.01) with oocyte nuclei diameter, granulosa and theca layer heights. However, oestradiol concentrations were positively and strongly correlated (P < 0.001) with oocyte and follicular diameters, and moderately with progesterone concentrations. Three phases of yolk depositions were found in the guinea hen, with the final phase terminating at 28 WOA, at a much smaller oocyte diameter than in the domestic chicken. Oestradiol might play a role in yolk deposition in this species.

Age-related histomorphometric and ultrastructural changes in the Sertoli cells of Japanese quail (Coturnix Coturnix japonica)

Prepared sections from pre-pubertal, pubertal, adult, and aged Japanese quail testes were examined by light microscopy and transmission electron microscopy (TEM) and measurements of seminiferous tubular diameter (STD), luminal diameter (SLD), epithelial height (SEH) and cross-sectional area of the seminiferous tubules (AST) were taken using an image analyzer. Apoptotic Sertoli cells with features such as cell shrinkage and chromatin condensation were observed in pre-pubertal and aged quail. There was a significant difference between the mean Sertoli cell number (SCN), SLD, SEH, STD and AST among the four age groups (P < 0.001). The highest SCN (mean ± standard error) was recorded in the adult (30.53 ± 0.42), with the aged group displaying the lowest mean (11.80 ± 0.27) SCN. Spearman's rho correlation coefficients demonstrated a strong relationship between the SCN and SEH in the pubertal (ρ=0.915; P < 0.001), adult (ρ=0.878; P < 0.001), and aged (ρ=0.858; P < 0.001) groups, while a significant moderate correlation was observed in the pre-pubertal (ρ=0.606; P < 0.001) group. There were significant moderate correlations between the SCN and STD in the pre-pubertal (ρ=0.445; P < 0.001), pubertal (ρ=0.653; P < 0.001), adult (ρ=0.440; P < 0.001), and aged (ρ=0.514; P < 0.001) groups. Furthermore, significant moderate correlations were estimated between the SCN and AST in the pre-pubertal (ρ=0.453; P < 0.001), pubertal (ρ=0.661; P < 0.001), adult (ρ=0.393; P = 0.001), and aged (ρ=0.498; P < 0.001) groups. This study provides baseline data on the morphology and development of the Sertoli cell, as well as testicular morphometry in avian species during the pre-pubertal, pubertal, adult, and aged stages using the Japanese quail as a model.

Sex differences in serum steroid hormone levels during embryonic development in hen eggs

This experiment was conducted to explore the differences of serum steroid hormones with age and sex in hen eggs during incubation periods for identification of males and females. The concentrations of estrone (E1), estradiol (E2), estriol (E3), testosterone (T), androstenedione (A4), and dihydrotestosterone (DHT) in serum were measured by enzyme-linked immunosorbent assays in chicken embryos on 8, 10, 12, 14, and 16 D, respectively. During the development of chicken embryo, egg weight loss was closely related to age but no sex. However, it was found that both age and sex significantly affected hormones and had obviously more effect on androgens levels. Besides E2 and T, other steroids such as E1, A4, and DHT were also significantly correlated with sex (P < 0.05). Notably, the level of T and the ratio of T to E2 were significantly higher in males than females (P < 0.05). The ratio of E1 to E2 displayed different trends in different sexes, which increased in males but decreased in females. The distribution proportions of androgens and estrogens kept stable level during the late hatching periods of 12 to 16 D. The sex differences of steroids were more obvious at the late hatching stage through PCA. These suggested that the serum hormones differences in male and female embryos played a vital role in sexual differentiation. These findings not only provided the theoretical basis for sex determination of fertilized eggs in egg-laying hen strains, but also contributed to develop a non-invasive way to sex determination of fertilized eggs to meet the modern commercial application.