Morphology of the cockerel's comb after androgen administration

Abstract

1. Androgen receptor (AR) expression and morphological changes in blood capillaries were investigated in the comb of cockerels, both untreated controls and after the administration of testosterone (T) or the androgen antagonist flutamide (F) for 7 weeks. 2. Twenty-six male Single Comb White Leghorn roosters were divided into T-treated, F-treated and untreated groups. Tissue sections were examined histologically, immunohistochemically, and comb blood vessel castings were analysed by scanning electron microscopy. 3. Histologically, the capillaries of the peripheral dermis layer in the T-treated group were dilated compared with controls. Many red blood cells were seen in the lumen. Although the capillary diameter in the F-treated group did not show a significant difference as compared with control, blood capillaries with small diameters were often observed, and there were few red blood cells in the capillaries. Some capillary castings were extended markedly in the T treated group, and small blood vessels were observed arborising from the extended blood capillaries. In contrast, all capillaries were slender in the F-treated group, and the casting surface was rough. 4. Immunoreactivity for AR was found in capillary endothelial cells in the peripheral dermis layer of the comb. The intensity of staining in these cells was increased in the T-treated group but was reduced in the F-treated group. 5. It is concluded that immunoreactivity for AR was found in capillary endothelial cells in the peripheral dermis layer of the rooster's comb. The intensity of staining in these cells was increased in the T-treated group but reduced in the F-treated group. Thus, the capillary endothelial cells in the peripheral dermis layer of the comb are androgen targets.

Comb Atrophy after Bile Duct Ligation in Chickens

“…However, the atrophic combs of BDL chickens were characterized by blood capillaries with smaller diameters, reduced acid mucopolysaccharides, thinning of the stratum germinativum of the epidermis and dermis, and reduced AR immunostaining intensity. These results suggest that affected cells in atrophic combs are androgen targets (Shanbhag and Sharp, 1996;Yoshioka et al, 2010). The histological characteristics of atrophic combs were similar to those observed in androgen antagonist flutamidetreated chickens (Yoshioka et al, 2010).…”

“…These results suggest that affected cells in atrophic combs are androgen targets (Shanbhag and Sharp, 1996;Yoshioka et al, 2010). The histological characteristics of atrophic combs were similar to those observed in androgen antagonist flutamidetreated chickens (Yoshioka et al, 2010). That study found AR in the nuclei of the stratum germinativum, the capillary endothelial cells in the peripheral dermis layer as well as fibroblasts in the comb.…”

“…The intensity of staining in these cells increased in the testosterone-treated group but was reduced in the androgen antagonist flutamide-treated group. Thus, we suggest that the capillary endothelial cells in the peripheral dermis layer of the comb, in addition to the stratum germinativum and fibroblasts, are also androgen targets (Yoshioka et al, 2010).…”

Genome-Wide Association Studies for Comb Traits in Chickens

“…Androgen’s actions are mediated by AR controlling the growth of the comb [ 64 ] and involved in the male reproductive system, stimulating testis and comb growth [ 65 ]. While stimulated with exogenous testosterone and dihydrotestosterone, the comb grows larger [ 66 ].…”

Sex Reversal in Birds

“…In the chicken, these traits include enlarged spurs, wattles, and comb in males, compared to smaller features in females. Masculinisation of the comb and wattle in males is attributed to testosterone [Zeller, 1971;Shanbhag and Sharp, 1996;Yoshioka et al, 2010;Lambeth et al, 2016a]. The mechanism regulating leg spur development seems to vary among species or even among strains [Lambeth et al, 2016a].…”