Jeannine Doerr-Schott

LHRH-like system in the brain of Xenopus laevis daud

SummaryRabbit antiserum to synthetic LHRH was used with the immunofluorescence technique to identify the LHRH-secreting neurons and their axonal pathways in the brain of Xenopus laevis. Three groups of immunoreactive neurons were identified: the first, in the telencephalon, is a paired group of cells scattered near the two telencephalic ventricles; the second group lies near the preoptic recess; the third group occurs in the ventral wall of the infundibulum. Two principal neuronal pathways were observed: Fibres originating from the dorsally located telencephalic neurons converge on the cephalic median plane where they form a single bundle behind the telencephalic furrow. This bundle descends towards the anterior border of the preoptic recess where it divides into two nerve bundles which pass on either side of the preoptic recess, run above the optic chiasma then cross the infundibular floor and finally terminate in the median eminence. The second pathway is more direct. The more ventrally located telencephalic LHRH cells give rise to this second pathway. Their axons converge with the other LHRH fibres near the lateral border of the preoptic recess. Most of the LHRH nerve fibres terminate in the median eminence although some terminate near the paired pars tuberalis. No reaction was observed after the use of antiserum absorbed with synthetic antigen.

Immunohistochemical localisation of substances reactive to antisera against α-and β-endorphin and met-enkephalin in the brain of Rana temporaria L.

SummaryIn the brain of Rana temporaria, two distinct systems reactive with α- and β-endorphin antisera, respectively, and with a met-enkephalin antiserum, have been detected immunohistochemically.Neurons reacting with α- and β-endorphin antisera are located (1) in the preoptic nucleus, and (2) in the pars ventralis of the tuber cinereum. Immunoreactive nerve fibres of both groups of perikarya end in the infundibular floor near the capillaries and the preoptico-hypophysial tract. Control reactions have shown that the immunoreactivity is suppressed by the corresponding antigens, but also by β-LPH. In view of these results the immunoreactive systems examined correspond to an α/β-endorphin system or a lipotropinergic system.Neurons reacting with the met-enkephalin antiserum are located in the paraventricular organ. Intense immunofluorescence was observed in the infundibular floor. Controls show that the labelling by met-enkephalin antiserum is exclusively suppressed by met-enkephalin.In the pituitary gland, on the other hand, α- and β-endorphin antisera reveal: 1) the MSH/ACTH-like cells of the pars intermedia and 2) the ACTH-like cells of the pars distalis.

Evolution des cellules gonadotropes β au cours du cycle annuel chez la grenouille rousse Rana temporaria L. etude au microscope electronique; Observations histochimiques et cytophysiologiques

Abstract Beta gonadotropic cells of the pituitary of the common frog, Rana temporaria , were studied by electron microscopy and by histochemical methods. The β cells contain basophilic and acidophilic granules. Three phases can be distinguished in the annual secretory cycle: (1) An accumulation phase of secretory granules (October to March). During this period, large sized β cells contain numerous granules of secretion (100 to 600 mμ) and a reduced Golgi complex. (2) A quick degranulation phase (March) characterized by the recovery of cellular activity, during which two cytological changes can be observed: (a) a resorption of secretory granules (600 to 700 mμ); (b) an increase in size of the Golgi complex. (3) A secretion phase (April to October). During this there is a decrease in the number of secretory granules; the fact that this is correlated with an increase in their size (75 to 900 mμ) suggests that it results from their fusion. At the same time the Golgi complex is well developed and the size of the β cells decreases. During this phase a new cycle of elaboration and accumulation is beginning in some other cells. The three phases of the secretory cycle of the gonadotropic cells correspond to the three main periods of the sexual cycle as described by Gallien (1940) . The electron microscopic study shows: that the acidophilic elements have neither the size nor the structure of typical acidophilic granules; that they are not identical with the mitochondria, and that they are only present at the time of secretion of the granules, which suggests that they are stages of granule destruction.

Immunohistochemical demonstration of TSR-, LH- and ACTH-cells in the hypophysis of tadpoles of Xenopus laevis D.

SummaryBy use of the immunofluorescence technique TSH-, LH- and ACTH-cells were localized in the hypophysis of tadpoles of Xenopus laevis. The first signs of the activity of these cells were observed in early stages of the development, i.e., stage 39 for ACTH, and stage 42 for TSH and LH.

A Triple Ultrastructural Immunogold Staining Method. Application to the Simultaneous Demonstration of Three Hypophyseal Hormones

The triple ultrastructural immunocytochemical labeling technique described here is based on the use of three different antisera raised in two different animal species: rabbit anti-corticotropin (R-ACTH), guinea pig anti-prolactin (GP-LTH) and rabbit anti-gonadotropin (R-LH beta). Staining is carried out on both sides (A and B) of the same tissue section. First, side A is incubated with a mixture of R-ACTH and GP-LTH and then with a mixture of the two corresponding species-specific immunoglobulins (IgG) adsorbed respectively to 5 and 20 nm gold particles: goat (G) anti-R IgG 5 + G anti-GP IgG 20; second, side B is incubated with R-LH beta, followed by species-specific secondary antibodies adsorbed in 10 nm gold particles; G anti-R IgG 10. With this technique, we demonstrated, on the same thin section, ACTH, LTH, and LH cells. The immunocytochemical procedure used has proved useful for simultaneous ultrastructural localization, on the same thin section, of three different antigenic sites. This technique, applied to other materials, could provide interesting information in several biological fields.

Immunohistochemical localization of a gastrin-like peptide in the brain of an amphibian, Xenopus laevis Daud.

SummaryThe indirect immunofluorescence technique was used to demonstrate a substance reacting with gastrin antisera in the brain of Xenopus laevis.Immunoreactive material was found in two sites: (1) In the caudal hypothalamus more precisely in the nucleus infundibularis ventralis, (NIV) of the pars ventralis of the tuber cinereum, (PVTC). The fluorescent axons of the reactive parikarya of the NIV give rise to two symmetrical tracts which run rostro-ventrally and join, in the infundibular floor, the preoptico-hypophysial tract, where they form an uneven median tract coursing caudally and running along the medio-tuberal area before entering the external zone of the median eminence. (2) In the anterior preoptic area (APOA), where numerous nerve fibers and endings form a dense network near the preoptic recess. The exact origin of these terminals has not yet been determined.Control of immunohistochemical specificity shows that the labeling by gastrin antisera is suppressed by gastrin (2–17), but also by cholecystokinin (CCK) and pentagastrin (Peptavlon). These results indicate that the immunoreactive substance revealed belongs to the gastrin group and has an antigenic determinant composed of the amino acid sequence or a portion thereof common to gastrin, CCK and Peptavlon (Trp-Met-Asp-Phe).It should be emphasized that, in the brain of Xenopus laevis, both gastrinimmunoreactive sites correspond to the sites of uptake of steroid hormones (Kelley et al., 1975; Morrell et al., 1975).

Ultrastructural Identification of gastrin-like immunoreactive nerve fibres in the brain of Xenopus laevis by means of colloidal gold or ferritin immunocytochemical methods

SummaryBy use of an anti-gastrin serum and colloidal gold- or ferritin-labelled sheep anti-rabbit γ-globulins, nerve fibres and nerve terminals containing a gastrin-like substance were characterized at the ultrastructural level in the median eminence of Xenopus laevis. These immunoreactive fibres contain neurosecretory granules displaying medium to high electron density and a mean diameter of 75 nm. Labelling intensity varies from granule to granule. This is the first demonstration at the ultrastructural level of the precise location of a gastrin-like hormone in the median eminence of a vertebrate.

Détection par immunofluorescence des cellules corticotropes et mélanotropes dans l'hypophyse de la grenouille, Rana temporaria L., au cours du développément

During the embryonic and larval developmental stages of the frog, Rana temporaria L, anti-β 1–24, α 17–39 corticotropine, α and β MSH antibodies were used to define, with immunofluorescence technique, the appearence of corticotropic and melanotropic cells.SummaryDuring the embryonic and larval developmental stages of the frog, Rana temporaria L, anti-β 1–24, α 17–39 corticotropine, α and β MSH antibodies were used to define, with immunofluorescence technique, the appearence of corticotropic and melanotropic cells.A very small number of fluorescent corticotropic cells appears for the first time during the embryonic stage (10 mm), just before the differentiation of the pars intermedia. The cells are small, their large nucleus is surrounded by a fine rim of fluorescent cytoplasm.During premetamorphic stage, the anti-ACTH antibodies (anti-β 1–24 and anti-α 17–39 corticotropine) reveal more fluorescent cells in the whole pars distalis. The pars intermedia cells can also be visualized by both antisera.At the end of prometamorphosis and during climax the corticotropic cells show a more precise localization. As in adult frog pars distalis, they are concentrated in the rostral half of the lobe. With the same technique anti-α and β MSH antibodies reveal only the cells of the pars intermedia. No other cell type of the pars distalis reacts with these antibodies. This technique has the advantage to show that the ACTH and the MSH cells appear very early during the embryonic life.

La “pars tuberalis” de Rana temporaria L.: cytologie et ultrastructure

It is possible by electron microscopy to distinguish two different zones in the pars tuberalis of Rana temporaria. The perikarya are situated in the central zone of the organ, while the peripheral zone is occupied by the cellular extensions. Secretory activity is evident in these cells. The granules, which accumulate in the extensions, originate in the Golgi system. This is formed of a number of dictysomes scattered in the cytoplasm of the perikarya and of the cellular extensions.

Gastrin-like peptides in the amphibian brain: An immunohistochemical study

Peptides homologous to the gastro-intestinal hormones, gastrin and cholecystokinin (CCK), are present in the brain. Using immunohistochemistry we localized a neurosecretory system, reacting with antigastrin sera, in the brain of amphibians by light and electron microscopy. It has a dual location: (1) in the nucleus infundibularis ventralis (NIV) two groups of perikarya give rise to fibre tracts which join up in the infundibular floor and end in the external zone of the median eminence; (2) in the preoptic area nerve fibres and endings are found near the preoptic recess. At the electron microscope level, the immuno-colloidal-gold method revealed cells characterized by small immunoreactive dense granules, localized in the perikarya, nerve fibres and endings. Specificity controls showed that the immunoreacting substance(s) contain(s) all or part of the sequence (Trp-Met-Asp-Phe) common to gastrin, CCK and pentagastrin. The exact nature(s) and physiological function(s) of these substance(s) has (have) still to be defined.