Pyroclastic rocks are the product of explosive volcanism. They are often felsic (high in silica). Pyroclastic rocks are often the result of volcanic debris, such as ash, bombs and tephra, and other volcanic ejecta.henocrysts are crystals that are larger than the matrix and are identifiable with the unaided eye. Rhomb porphyry is an example with large rhomb shaped phenocrysts embedded in a very fine grained matrix. Volcanic rocks often have a vesicular texture caused by voids left by volatiles trapped in the molten lava.
July 9, 2014. Frozen sperm must be stored in extremely cold temperatures (-196 F), but in order to ensure that the fewest possible sperm are damaged, the freezing must be gradual. Generally, the following procedure is followed:
Thermal Regulation of the Testes. Successful spermatogenesis is achieved at temperatures a few degrees below core body temperature. The extra-abdominal location of the testes is critical to spermatogenesis. The testes may be several Celsius degrees cooler than core body temperature. Testicular Descent: In a number of mammalian species, including humans, the testes are extra-abdominal.