Morphological and functional peculiarities of mesenchymal cells in the pars tuberalis of the pituitary gland

Summary Following injection of high doses of horseradish peroxidase (HRP), mesenchymal cells distributed in the perisinusoidal space of the pars tuberalis of the hypophysis in cats, rabbits and Japanese quails, sequester the exogenously administrated peroxidase intensively. These cells are designated by the authors as horseradish peroxidase-uptake cells (HRP-uptake cells or HUC). HRP-uptake cells constitute a system of macrophages in the pars tuberalis of mammals and birds, and are located around the hypophysial portal veins. HRP-uptake cells differ in morphological and functional characteristics from similar cells in other parts of hypophysis. They are thought to play a role in the hypothalamic control of adenohypophysial secretion.Supported by grants (No. 144022, 237002) from the Ministry of Education, Science and Culture, Japan     

Immunocytochemical identification of proctolinlike immunoreactivity in the terminal ganglion and hindgut of the cockroach Periplaneta americana (L.)

Summary In the American cockroach, the distribution and connections of neuronal elements of the terminal ganglion-proctodeal nerve-hindgut system were investigated by means of immunohistochemical methods and axonal CoCl₂ iontophoresis. Proctolinlike immunoreactivity was localized within neurons of the terminal ganglion projecting into the proctodeal nerve on the one hand, and in nerve cells without a direct connection to this system on the other. Immunohistochemically, in whole mount preparations fibres of the proctodeal nerve and terminal structures in the hindgut musculature exhibit strong proctolinlike immunoreactivity. At the light- and electron-microscopic levels the pathways of about 30 somata of the proctodeal neural system were characterized by cobalt chloride iontophoresis. The relationships of cobalt filled and immunoreactive neuronal structures are discussed.For the preparation of tritiated proctolin we thank Dr. S. Reißmann, WB Biochemie, Sektion Biologie, FSU JenaThe authors wish to thank G. Schörlitz, Film- und Bildstelle, FSU Jena, for photographs of whole mount preparations and Ms. A. Zinßer and Mrs. B. Cosack for excellent technical assistance.     

Morphological aspects of the hypothalamic-hypophyseal system

Summary The ultrastructure of the tanycyte ependyma in male 160–180 g Wistar albino rats was studied under normal conditions and in experiments involving long-term suppression of ACTH secretion and its long-term stimulation. The former was accomplished by daily (for 8 days) intraperitoneal administration of dexamethasone phosphate at low (5 g/100 g) and high (100 g/100 g) concentrations. The effectiveness of suppression of the hypothalamic-hypophyseal-adrenal system in the experimental animals was judged by their reaction to two-minute ether stress (determination of plasma corticosterone) and by the results of measurement of the adrenal weights. Stimulation of ACTH secretion was achieved by bilateral adrenalectomy; the animals were examined on days 8, 10, 14, and 22 following the operation. The results obtained were in agreement with the previously established fact that there is a negative correlation between tanycyte activity and hypophyseal adrenocorticotrophic function (Akmayev and Fidelina, 1974). They also testified to the predominant involvement of the median eminence tanycyte ependyma (beta-tanycytes according to the authors' nomenclature) in these relationships.It is supposed that these correlations are regulated by a feedback mechanism and attest to the involvement of beta-tanycytes in the inhibiting control of hypophyseal adrenocorticotrophic function. The mechanism of this control may be explained alternatively: either the tanycytes transport ACTH-suppressing substances (catecholamines, corticosteroids, ACTH) from the CSF to the hypophyseal portal system or they themselves secrete substances possessing ACTH-suppressive activity. The authors distinguish several types of vesicles in the beta-tanycytes, the number of which changed with experimentally induced shifts in hypophyseal adrenocorticotrophic function. These vesicles are discussed in connection with the transport and secretory activity of the tanycytes and are considered to be a possible substrate of the hypothalamic inhibiting effect on ACTH secretion.     

A proposed phylogenetic relationship between sea cucumber polian vesicles and the vertebrate lymphoreticular system

Evidence is presented that Polian vesicles of the sea cucumber, Holothuria cinerascens, a member of an echinoderm class considered close to the vertebrate evolutionary line, are organs of inflammatory (including immunologic) responsiveness. As such, they might represent a rudimentary beginning of what later evolved into the vertebrate lymphoreticular system.     

Mechanisms towards compensation of long-term haemopoietic injury in mice after 5 Gy irradiation:In vivo andin vitro enhancement of superoxide anion production by granulocytes

This paper analyzes the long-term (6 and 12 months) function of mouse granulocytes after total body irradiation with a single dose (5 Gy) of X-rays. Superoxide anion production has been investigated in granulocytes from peripheral blood, and also in those harvested from long term bone marrow cultures, with the aim of correlating the environmental damage induced by radiation with the functional properties of granulocytes. Anin vivo andin vitro enhancement of superoxide anion production and protein levels in granulocytes from irradiated mice is described. The presence of some colony stimulating factor in the supernatant of cultures from irradiated mice could play an important role in the priming of granulocytes.     

Circular dichroism detection in HPLC

A circular dichroism-based detection system presents several advantages in the HPLC analysis of chiral compounds because of the selective monitoring of optically active molecules. Its use allows reliable determination of enantiomeric excesses and elution order. To this end, the application of empirical, semiempirical, and nonempirical methods to get stereochemical information from the CD signal is reported. Furthermore, recording the CD spectra on line and evaluation of the dissymetry factor make the CD detection very powerful in characterizing the stereochemistry of chiral eluates.     

Co-localization of ecdysteroid receptors and c-fos-like protein in the brain of Manduca sexta larvae

Summary The presence of c-fos, a marker for cell activation, was investigated in cerebral neurons actively expressing ecdysteroid receptors during larval-pupal development in the tobacco hornworm, Manduca sexta. Colocalization was accomplished by ecdysteroid autoradiography using the tritiated high affinity 20-hydroxyecdysone agonist ponasterone A and immunocytochemistry with an antibody to a peptide sequence which is highly conserved in both human and murine c-fos. Immunoreactivity to a c-fos-like protein(s) was present in nuclei of many neurons of all the developmental stages examined. However, with the exception of the optic lobe, cells expressing nuclear ecdysteroid receptors were more immunoreactive than non-ecdysteroid-binding neurons. These data suggest that ecdysteroid-induced gene activation and translation may involve c-fos expression. Offprint requests to: H.-J. Bidmon     

Variation in the genetic structure and reproductive biology of holm oak populations

Five polymorphic enzymatic loci were studied in 30 populations of Quercus ilex distributed from Crete to North Africa. A high within-population genetic diversity was found for each locus studied. Most of the alleles were common to all the populations, indicating that the holm oak corresponds to a single genetic entity. Observation of breeding system characteristics showed that the holm oak is monoecious, wind-pollinated, and likely to possess genetic autoincompatibility. Furthermore, studies of flowering phenology in a single population showed that the period of flowering varied notably among trees. An average of 29% of the trees showed inter-annual variation in flowering time. The male, female or vegetative investment also varied widely among trees from one year to another. This results in a diversification of pollen source received by a given tree each year, and also from one year to another.     

An antigen present in the Drosophila central nervous system only during embryonic and metamorphic stages

We report here about an antigen that is expressed in the central nervous system (CNS) of Drosophila only during the embryonic and metamorphic stages. In Drosophila, axonogenesis and synaptogenesis occur twice during the development: first in the embryonic and second in the metamorphic stages. We generated monoclonal antibodies (MAbs) in order to obtain molecular probes for analyzing axonogenesis or synaptogenesis in the CNS on the assumption that good candidates for molecules responsible for such phenomena must be present in the neuropil during those stages exclusively. As a result, we found MAb 66B2 whose intense immunoreactivity in the neuropil of the CNS was observed exclusively in the embryo and pupa, and not in the larva and adult. Immunoblot analyses showed that MAb 66B2 binds specifically to a protein with an apparent molecular weight of 350 K and neutral pl in the prepupal CNS. A significant amount of the antigen was isolated in forms that were soluble without detergent. Results of immunohistochemistry with MAb 66B2 in a primary culture of embryos showed that some live cells in the ganglion-like cluster were stained, and that neuronal cell bodies and neurites emanating from there were negative. These results strongly suggest that the 66B2 antigen observed in the CNS is an extracellular matrix component secreted from nonneuronal cells. These developmental changes in the 66B2 immuno-reactivity in the CNS presumably reflect dynamic changes of an extracellular matrix in the CNS that are accompanied by axonogenesis or synaptogenesis. © 1992 John Wiley & Sons, Inc.     

Peripheral nervous control of cold-induced reduction in the respiratory quotient of the rat

Cold-exposed rats show a reduction in the respiratory quotient which is indicative of a relative shift from carbohydrates to lipids as substrates for oxidative metabolism. In the present study, the effects of food deprivation and cold exposure on the respiratory quotient were observed. In addition, the involvement of the three main branches of the peripheral nervous system (sympathetic, parasympathetic, and somatic) was investigated by means of synaptic blockade with propranolol, atropine, and quinine, respectively. Both propranolol and quinine blocked the cold-induced decrease in respiratory quotient and increase in heat production, whereas atropine had only minor and very brief effects. It is concluded that both the sympathetic and somatic branches are involved in the metabolic changes associated with cold-induced thermogenesis and that the increase in metabolic heat production involves a shift from carbohydrate to lipid utilization irrespective of which of the two branches is activated.