Sertoli cells have receptors for follicle stimulating hormone (FSH) and testosterone which are the main hormonal regulators of spermatogenesis. Hormones such as testosterone, FSH and luteinizing hormone (LH) are known to influence the germ cell fate. Their removal induces germ cell apoptosis.
In very basic terms, ISO is the level of sensitivity of your camera to available light. The lower the ISO number, the less sensitive it is to the light, while a higher ISO number increases the sensitivity of your camera. The component within your camera that can change sensitivity is called âimage sensorâ or simply âsensorâ.
ISO is the speed of the film, also known as the number printed on the box and the canister. FujiChrome Velvia 50 has an ISO of 50; Ilford Delta 400 has an ISO of 400. ISO or Film Speed is expressed as a number, which is generally doubled as it gets higher. For example 50, 100, 200, 400, 800, 1600, 3200.