DNA-synthesizing cells in human fetal thymus.

Fragments and suspensions of human fetal thymus were incubated in the presence of 3H-TdR to permit study of the distribution and morphology of DNA-synthesizing cells. Results of light and EM autoradiography showed that 1. although DNA-synthesizing cells were present in the medulla, the vast majority of these cells were localized in the thymic cortex, 2.

Histochemistry of 3beta-hydroxysteroid dehydrogenase in rat ovary. I. Amethodological study.

By recording the incubation time needed for initial appearance of the red and blue formazans the reliability of the histochemical method for 3beta-HSD was investigated: 1. Prefixation of small tissue blocks with 1% W/V methanol-free formaldehyde (pH=7.2) for up to 30 min preserved morphological integrity as well as maximal enzyme activity.