[Truncated abstract] The aims of the present project were to extend understanding of the contractile physiology of the tunica dartos muscle, especially the cellular mechanisms and the substances involved in activating contraction and relaxation of the dartos during electrical, pharmacological, and thermal stimulation and also study the effects of dysregulation of intra-scrotal temperature on the endocrine function of the testes. In scrotal mammals, testicular thermoregulation is achieved by local and central mechanisms that are independent of the temperature regulatory mechanisms of the body core. The scrotum plays this important role in thermoregulation via several structural and functional adaptations, including the contraction of the cremaster and the dartos muscles, the presence of a large number of apocrine sweat glands, the absence of subcutaneous fat and the activity of the counter-current heat exchange system in the pampiniform plexus. The tunica dartos is a smooth muscle found in the subdermal layer of the scrotal skin. Contraction of the dartos reduces the surface area of the scrotum and blood flow to the scrotal skin, preventing heat loss. Dartos relaxation causes excess heat to be removed. Therefore, the dartos plays an important role in the thermoregulation of the testes and congenital absence of the dartos leads to infertility. It was known that the isolated dartos muscle contracts in response to electrical field stimulation (EFS) and that it is temperature sensitive. The relative contractile forces produced by explants of tunica dartos of the Wistar rat were 100%, 134% and 137% respectively to EFS, noradrenaline and cooling (15oC). Extension of these findings suggested that the dartos receives sympathetic innervation and contracted in response to noradrenaline via α-1 receptor stimulation...
|Qualification||Doctor of Philosophy|
|Publication status||Unpublished - 2012|