Adrenoreception characteristics of the neurons of the superior cervical and caudal mesenteric sympathetic ganglia of the cat]

Experiments were conducted on the supeior cervical and the caudal mesenteric sympathetic ganglia of a cat; it was shown that dophamine (DA), similarly to noradrenaline (NA) and adrenaline (A), depressed the cholinergic conduction. The activity of DA in the superior sympathetic ganglion was less than that of the NA and A 2- and 3-fold, respectively, and in the caudal mesenteric ganglia DA was 50 times more active than NA by the capacity to depress the cholinergic conduction. The effects of DA and NA in the superior cervical ganglia were eliminated by dyhydroergotamine, phentholamine and haloperidol, but not by tropaphen and chlorpormazine. In the caudal mesenteric ganglia the inhibitory effect of NA was decreased by phentholamine, dihydroergotamine and chlorpromazine, but not by haloperidol. On the contrary, haloperidol and chlorpromzine decreased the depressive effect of DA on the cholinergic conduction in the caudal mesenteric ganglion, whereas phentholamine, dihydroergotamine and deseryl proved to be ineffective. It is supposed that the manifestation of the dopaminergic mechanism of inhibition of cholinergic conduction in the caudal mesenteric sympathetic ganglion could underlie the dilatation of the mesenterial and renal vessels and its hypotensive action caused by DA.     

Structure and Histochemistry of Stomata and Epidermal Cells in Five Species of Polypodiaceae

The epidermal structure of the five species of ferns, Arthromeriswallichiana (Spr.) Ching., Drymoglossum piloselloides (Prest.),Drynaria quercifolia (L.) J. Smith, Lepisorus nudus (Hook.)Ching. and Pyrrosia nuda (Gies.) Ching., has been investigated.Fifteen types of stomatal structures have been identified ofwhich copolo-desmocytic and coperi-desmocytic are new types.Four more possible stomatal structures: ccpolo-peri-, codesmo-polo-,codesmo-peri- and duplodesmocytic, are suggested. Localizationof starch, insoluble polysaccharides, protein and lipids hasbeen examined histochemically in the guard cells, subsidiarycells and epidermal cells. In Drynaria starch plastids and plastidscontaining both starch and protein are present in guard cells.Starch plastids are present in the subsidiary cells of all speciesexcept in Arthromeris, whereas, they are present in epidermalcells of only Drymoglossum and Lepisorus. Granular or amorphousinsoluble polysaccharides (other than starch) are present inguard cells of all the species, in the subsidiary cells of Arthromeris,Drynaria and Pyrrosia, and in the epidermal cells of Pyrrosia.Except in Pyrrosia lipids are present in the guard cells. Subsidiarycells of Drynaria and the epidermal cells of Arthromeris andDrynaria show lipid bodies. The presence of plasmodesmata andectodesmata is demonstrated in the epidermal cells of Drymoglossum.     

Osteogenesis in cultures of limb mesenchymal cells

The results of previous reports demonstrated that osteoblasts develop in cultures derived from phenotypically unexpressive stage 24 chick limb mesenchymal cells. The observations reported here suggest that initial cell plating densities may provide environmental conditions deterministic to a particular limb phenotype. Quantitative microscopic studies, histochemical localization of calcium phosphate, and electron microscopy indicate that osteoblasts develop in cultures derived from stage 24 limb mesenchymal cells. Additionally, 1–3% of the cells from stage 24 limbs are associated with mineral deposits when plated at initial high densities (5 × 10⁶ cells per 35-mm culture dish), while more than 50% of the cells are associated with cartilage by Day 9. Cultures plated at intermediate seeding densities (between 2.0 and 2.5 × 10⁶ cells per 35-mm culture dish) have minimal cartilage development, and approximately 20% of the cells are associated with mineral by Day 9. Furthermore, cultures prepared from stage 31 limb mesenchymal cells form well-developed bone nodules with both osteoblasts and osteocytes present, but no cartilage. It is clear from these observations and from a consideration of the initiation of osteogenesisin vivo that the initiation of bone development in the limb is not associated with cartilage development. Based on these studies and observations on the effect of nutrient factors on phenotypic expression in culture, an hypothesis is presented relating differential vascularization and nutrient flow to the determination of limb phenotypesin vivo.     

Study of some oxidoreductases in nerve tissue culture]

A change in the activity of succinic dehydrogenase, of the NAD- and NADP-diaphorases was studied in the dissociated culture of the cerebellum of neonatal rats under the effect of immune serum of the animals with an experimental allergic pertussis encephalomyelitis. There was revealed an increase in the activity of oligodendrocytes following a 3-hour exposure with the immune serum and a reduction of the activity of the enzymes under study in the same cells after a 12-hour exposure of the cultures with the serum. In difference from oligodendrocytes, the astrocytes displayed a high activity of all the enzymes under study after a 12-hour exposure.