Perfusion method for preparing pig brain cortex for Golgi-Cox impregnation

The perfusion procedure described in this paper produces high quality impregnation of pig visual and somatosensory cortical neurons with a Golgi-Cox solution. Starting within 30 min after death, pig heads were perfused with a fixative solution composed of a mixture (v/v) of liquid phenol, 5%; formalin, 14%; ethylene glycol, 25%; methanol, 28%; and water, 28% for two periods of 4 hr each. After perfusion, the heads were chilled for at least 18 hr. The entire brain was removed from the skull and then placed in 10% buffered formalin, where it remained for at least 10 days before taking the blocks that were to be immersed in the Golgi-Cox solution. Three weeks spent in the Golgi-Cox solution typically produced uniform neuron impregnation. The tissue blocks were then embedded in celloidin and sectioned at 120 micron. This procedure avoids the following difficulties: Golgi-Cox methods that produced excellent results with rodent or primate tissue were unsuccessful with pig tissue, placing fresh tissue in Golgi-Cox solution resulted in incomplete neuron impregnation, and immersion fixation in 10% buffered formalin without perfusion resulted in excessive staining of glia.     

Quantitative characteristics of radiation injury of the spermatogenic epithelium and the rate of its recovery after exposure to fast neutrons and gamma-radiation

The paper submits the results of studies on the kinetics of spermatogenous epithelium cell number after exposure to fast neutrons (60-300 cGy) and gamma-radiation (200-600 cGy). It was shown that a relative decrease in the quantity of spermatocytes is determined by an exponential dose-response curve with D0 of 35 and 120 cGy for neutrons and gamma-radiation respectively. For spermatides and spermatozoa a single D0 value of 20 and 55 cGy was obtained for neutrons and gamma-radiation respectively. As the radiation dose increases the recovery process in the epithelium is substantially decelerated. The equation T1/2 = T1/2(0)e0.0009D well describes the dependence of the half-recovery period T1/2 upon the equivalent dose.