Histochemical Studies on the Skin: II. the Activity of the Succinic, Malic and Lactic Dehydrogenase Systems During the Embryonic Development of the Skin in the Rat

Abstract

Animal Material. Twenty-five rats of the Wistar strain were used. Twelve of these were embryos (3 each on the 12th, 14th, 16th and 18th days of gestation), 2 were new-born (the period of gestation varied from 19 to 21 days), 3 were ten-day-old, 3 were fifteen-day-old and 5 were adults. The adult rats weighed approximately 100 g. New-born and older rats were killed by a blow on the neck without anesthesia. Hair was shaved off the back, and skin specimens were taken from there and cut into small square pieces. These pieces were immediately immersed for about five minutes into ice-cold 0.1 M Sorensen's phosphate buffer and then used for frozen sections. (The buffer had a pH of 7.6 for the study of the succinic dehydrogenase system and a pH of 7.4 for the study of the malic and lactic dehydrogenase systems). In embryos, skin was removed from the back while they were still alive. Frozen sections, approximately 20 in thickness, were made from the fresh skin specimens. Histochem feat Demonstration of the Succinic Dehydrogenase System (SDS). Ogawa and Zimmerman's method (7) was employed to demonstrate the succinic dehydrogenase system. As a rule, nitroneotetrazolium chloride (nitro-NT) was used as an electron acceptor. Occasionally, however, nitro-blue tetrazolium (nitro-BT) was used, instead.