Related Experiment Video
Updated: Jul 18, 2026

Establishment of Rat Models Mimicking Gender-affirming Hormone Therapies
Published on: January 10, 2025
Deficiency of growth hormone receptor does not affect male reproduction in dwarf chickens
1Department of Animal Genetics and Breeding, College of Animal Science and Technology, China Agricultural University, Beijing 100094, China.
Abstract:
Sex-linked dwarf chickens caused by the mutation of the growth hormone receptor gene are characterized by normal growth hormone (GH), very low insulin-like growth factor I (IGF-I) level in the blood, and reduced growth. It has been demonstrated that the sex-linked dwarfing gene has negative effects on female reproduction. In the current study, dwarf cocks and their phenotypic normal siblings were used to investigate the effects of dwarf gene on male reproduction. Dwarf cocks grew slower than the normal cocks did, and at 20 wk of age, their BW were 36.4% smaller. However, all parameters for semen quality, including volume, sperm concentration, viability, mobility, pH, and percentage of abnormal sperms, examined at 30 wk of age showed no significant difference between normal and dwarf cocks. The fertility of dwarf cocks was 95.2%, and the normal was 92.4%. The concentrations of GH and IGF-I in serum and seminal plasma were measured with RIA and ELISA, respectively. The serum GH in the dwarf cocks was significantly higher than their normal siblings (P < 0.05), whereas the serum IGF-I in the dwarf cocks was very low. However, the concentration of seminal IGF-I in dwarf cocks was similar to that of their normal siblings, indicating that IGF-I might be produced and acted independently in testis. In conclusion, the deficiency in GH receptor did not affect the male reproduction in dwarf chickens, and the fertility of dwarf cocks could be satisfactory for production when artificial insemination was adopted.
Related Concept Videos
The Ratio of X Chromosome to Autosomes
Normal male Drosophila has a ratio of one X chromosome to two sets of autosomes. In contrast, normal female Drosophila...
Sex-linked Disorders
Dosage Compensation
In addition to sexual development, the X chromosome has genes involved in autosomal functions such as brain development and the immune system. Therefore, males and females with distinct numbers of X chromosomes will have...
The Y Chromosome Determines Maleness
Evolution
Around 300 million years ago, the two sex chromosomes diverged from two identical autosomal chromosomes. Over time, the Y chromosome has lost most of its genes, shrinking in size. Today,...
Target Cell Response to Hormones
Notably, the cellular response can be regulated by altering the number of receptors expressed in the cell. For example, prolonged exposure to elevated hormone levels results in a gradual decline or down-regulation in the number of receptors for that specific hormone on the cell surface. Conversely, in response to low hormone levels, cells may use up-regulation, producing an...
Background and Environment Affect Phenotype
An example of how genetic background affects phenotype can be seen in horses. The Extension gene in horses is responsible for their coat color. A wild-type gene (EE) produces black pigment in the coat, while a mutant gene (ee) produces red pigment. A...
