Révision systématiquedu genre Steginoporella smitt, 1873 (Bryozoa Cheilostomata)

Systematic revision of the genus Steginoporella: until now about eighty species were described. Only twenty recent species and thirty-four fossil ones are maintained. Several species and subspecies are new.The main interest of this revision is to establish a biostratigraphical scale: the settlement of this scale is based on the known stratigraphical distribution and on an attempt of phylogeny.The second advantage is ecological: all recent species live in marine tropical environment. The Steginoporella are good paleoecological indicators.At last, the establishment of a paleobiogeography, even incomplete and not definitive, allows to understand more easily recent distribution of Steginoporella connected with the great events of earth evolution.     

Colorimetric determination of acetaldehyde in the presence of formaldehyde

A procedure is described that enables use of the p-phenylphenol color reaction to determine acetaldehyde in the presence of formaldehyde. The sample is first treated with an acidic 2,4-pentanedione reagent, which selectively removes formaldehyde. The method is applicable to blochemical reactions using tissue preparations.     

Nonallelic histone gene clusters of individual sea urchins (Lytechinus pictus): mapping of homologies in coding and spacer DNA

The linear arrangement and lengths of the spacers and coding regions in the two nonallelic histone gene variant clusters of L. pictus are remarkably homologous by R loop analysis and are similar in general topography to the histone gene repeat units of other sea urchins examined to date. No interventing sequences were detected. The coding regions of these two histone gene variants share considerable sequence homology; however, there are areas of nonhomology in every spacer region and the lengths of the nonhomologous spacers between the H2A and H1 genes are not the same for the two repeat unit classes (inter-gene heterogeneity). Combining length measurements obtained with both R loops and heteroduplexes suggests that the DNA sequences of the analogous leader regions for the two H1 mRNAs are nonhomologous. Similar observations were made for the H4 leader sequences, as well as the trailer region on H2B. S. purpuratus spacer DNA segments share little sequence homology with L. pictus; however, the analgous coding (and possibly flanking) regions have conserved their sequences. The various coding and spacer regions within a repeat unit do not share DNA sequences. Thus certain areas in the sea urchin histone gene repeat units have been highly conserved during evolution, while other areas have been allowed to undergo considerable sequence change not only between species but within a species.     

Structural changes occurring in interrenal tissue of the duck (Anas platyrhynchos) following adenohypophysectomy and treatment in vivo and in vitro with corticotropin

Adrenal glands from ACTH-treated intact ducks and chronically adenohypophysectomized ducks showed clear zonation into a subcapsular zone (SCZ) and an inner zone (IZ). Adenohypophysectomy caused ultrastructural changes in the IZ but not in the SCZ cells. These included increases in lipid droplets, changes in mitochondrial cristae from tubular to shelf-like, and changes in the shape of the nuclei from spherical to crenated. These changes were reversed by treatment with ACTH. Also, cells of the IZ, but not the SCZ, of adrenals from intact birds given ACTH showed more SER, more dense bodies, fewer lipid droplets and more prominent Golgi complexes. IZ cells incubated in buffer containing no ACTH developed mitochondria with shelf-like cristae and numerous opaque granules in the matrix. Exposure to buffer containing ACTH caused the mitochondrial cristae to become tubular and the matrix granules either decreased in number or disappeared. The granules could be extracted by incubating sections with chelating agents. The mitochondria in SCZ cells did not respond structurally to the presence of ACTH in the incubation medium but the matrix granules, like those in IZ cells, responded to the presence of chelating agents.     

Isotocinergic neurons in the goldfish hypothalamus: Physiological and morphological studies on chemically identified cells

Summary Isotocinergic (IT) neurons show physiological and morphological characteristics that are similar to those of other preoptic neuroendocrine cells in the goldfish. Preoptic IT cells show resting membrane potentials of 20–55 mV, action potentials of up to 100mV, and physiological evidence of axonal branching. Dye-marked IT cells measure 14–56 m, their dendrites projecting to the ependyma and into the hypothalamic neuropil, their multiple beaded axons projecting to the pituitary. Indirect immunofluorescence identifies these dyemarked cells as IT. By combining electrophysiological, dye-marking and immunocytochemical techniques we can now, for the first time, study single, antidromically-identified peptidergic neurons of a specific type in vertebrate and invertebrate species.Supported by Grants from the USPHS (NS-13411 and NS-05696)The authors wish to thank Ms. S. Curtis for editorial assistance, Ms. D. Cronce for skillful technical assistance, Dr. W.W. Stewart for helpful suggestions and for his generous gift of Lucifer Yellow-CH, Dr. M. Manning for his generous gift of high quality peptides, and Dr. R.R. Dries and J.D. Fernstrom for kindly supplying antisera     

Neuroglandular contacts between vasopressin-reactive fibers and cells of the pars tuberalis in the rat

Summary In electron micrographs fibers containing vasopressin-immunoreactive elementary granules 100–120 nm in diameter are observed within the basal lamina of the adenohypophyseal pars tuberalis adjacent to the rostral portion of the median eminence. The concept of a neuroglandular transmitter function of vasopressin is discussed.Supported by the Deutsche Forschungsgemeinschaft (Grant Nr. Kr. 569/2) and the Stiftung VolkswagenwerkThe excellent technical assistance of Mrs. Helga Prien is thankfully acknowledged     

The hypothalamo-hypophysial system in the ground squirrel,Citellus erythrogenys Brandt

Summary Monthly observations of the Gomori-positive hypothalamo-hypophysial neurosecretory system (HHNS) of the ground squirrel, Citellus erythrogenys Brandt, were carried out light microscopically using several quantitative methods. From the beginning of hibernation, formation of neurosecretory material (NSM) in the neurosecretory cells (NSC) progressively decreases and release of neurohormones from the HHNS is almost fully inhibited. A maximal accumulation of NSM in the perikarya of the NSC and in the posterior pituitary (PP) is found in December. By this time the volume of the cell nuclei and nucleoli is at a minimum. Signs of activation of the HHNS appear and become more conspicuous as the time of arousal from torpor approaches. The amount of NSM in the NSC and the PP decreases simultaneously with the increase in volume of the NSC. Hyperemia and activation of glial elements is visible throughout the HHNS. The morphological signs of activation reach their peak in March. After reproduction is completed (April to beginning of May), the NSC and the PP are almost devoid of NSM. Beginning with June and during the summer and autumn months a progressive accumulation of NSM in the NSC and the PP parallels gradual diminution in the volume of the NSC structures and the glial cells. Mechanisms and effector pathways by which the HHNS influences seasonal adaptation of the organism and reproduction are discussed.     

The fine structure of the cumulus oophorus during follicular development in sheep

Summary The cumulus and membrana granulosa of non-atretic ovarian follicles from primordial up to a stage shortly before ovulation were studied by electron microscopy.The follicular cells of primordial follicles were undifferentiated and rested on a thick basal lamina. In secondary follicles the endoplasmic reticulum had proliferated forming an anastomosing network. In early antral and antral follicles (0.5–2.0 mm dia.) the ER was composed of short cisternae, the mitochondria had elongated and gap junctions were first observed. In late antral follicles (3.0–5.9 mm dia.) gap junctions were frequent. In the cumulus the glycogen was associated with electron lucent areas whereas in the granulosa it was invariably associated with membranes. In large antral follicles large membrane bound bodies were present in the basal cells of the cumulus. At early oestrus a distinctive mitochondrial morphology was noted in the granulosa but not elsewhere in the follicles. At mid oestrus numerous annular nexuses were present in the granulosa but not in the cumulus. At late oestrus numerous lipid droplets were formed in both cumulus and granulosa, the boundary with theca interna became indistinct and the basal lamina became incomplete.Deceased     

Immunocytochemical demonstration of separate vasopressin-neurophysin and oxytocin-neurophysin neurons in the human hypothalamus

Summary With the use of immunocytochemistry, it was shown that both the supraoptic and paraventricular hypothalamic nuclei in humans contain at least two different neurophysins. These two human neurophysins are immunologically related to bovine neurophysin I and neurophysin II, respectively. One human neurophysin is associated with vasopressin, the other with oxytocin. Human vasopressin-neurophysin and oxytocin-neurophysin are located separately in two different types of neurons, which correspond respectively to the vasopressinergic and oxytocinergic neurons of both the supraoptic and paraventricular nuclei. The neurophysin of the human vasopressinergic suprachiasmatic neurons appears to be closely related to or identical with neurophysin of the vasopressinergic neurons of the human magnocellular hypothalamic nuclei.This investigation was supported by a grant from the Belgian Nationaal Fonds voor Geneeskundig Wetenschappelijk Onderzoek