The histochemical and ultrastructural basis of the cellular function of the human foetal adenohypophysis.

The cellular function of the adenohypophysis was studied on a material comprising the pituitary glands from 36 human foetuses. Based on the activity of the glucose-6-phosphate-dehydrogenase-NADPH(2) cytochrome c reductase system and the ultrastructural findings of free polyribosomes well developed granular endoplasmic reticulum extended Golgi-complex and secretory granules the three main functions of the pentose shunt was discussed: 1. the shunting of ribose-S-phosphate into nucleic acid synthesis 2. the generation of NADPH(2) for lipid synthesis in developing cytoplasmic membranes further supported by the findings of an activity of β-hydroxybutyrate dehydrogenase and of small scattered lipid droplets in some of the larger cells 3. the ATP production. With regard to the latter the roles of the Krebs cycle and the glycolytic cycle were discussed based on the activity of succinic dehydrogenase NAD-linked isocitrate dehydrogenase the strong activity of NAD-linked lactate dehydrogenase and the decrease in glycogen respectively. The extrusion of granules was discussed and correlated to current theories. Especially the findings of granules in close contact with the plasma membrane facing both the mesenchyma and the intercellular space as well as the findings of a strong activity of alkaline phosphatase localized to the plasma membrane suggest that the extrusion of granules may happen at any point of the cellular surface. Further support is the lack of an occlusion of the intercellular space in the areas of the continuous lamina basalis. Lastly the pitfalls in typing the different cells of the foetal adenohypophysis when using the conventional staining methods were discussed.