Maurice P. Dubois

LRF Producing Cells of the Mammalian Hypothalamus

SummaryThe demonstration of perikarya of mediocellular neurones producing LRF, using indirect immunofluorescence on slides and anti synthetic LRF antibodies, requires both their activation and the inhibition of their axoplasmic transport. This fact suggests that LRF is present in an immunoreactive form, but usually in very low concentrations.Perikarya of neurons producing LRF are found principally in the preoptic and septal areas of the rat and decrease caudally, particularly beyond the retrochiasmatic area.Most of the axons coming from these perikarya are incorporated in the hypothalamoinfundibular tract and terminate around the capillaries of the primary portal plexus, particularly those of interealar plexus. Other axons (or axon collaterals) may be found in various areas (suprachiasmal crista, epithalamus, amygdala, mesencephalon) and form circuits recalling the “extrahypophyseal pathways” described for the magnocellular Gomori-positive neurons of the SON and PVN. These axons are probably concerned in intersegmental regulations involving “neurosecretory synapses”, particularly of the axosomatic type.The placement of stereotaxic lesions was used to determine the topography and direction of axoplasmic flow of the axons transporting LRF.The infundibular immunoreactive material, already discernible at the end of gestation in the foetus, shows considerable variations between birth and puberty, during the estrous cycle and under various other physiological or experimental conditions.The observations made under various experimental or physiological conditions suggest that, in the guinea-pig in particular, the greater part of the hypothalamic immunoreactive material is concentrated in the infundibular area. This area of accumulation is comparable to the distal neurohypophysis of the Gomori-positive neurosecretory system coming from the SON and PVN.

Ontogenesis of cells producing polypeptide hormones (ACTH, MSH, LPH, GH, prolactin) in the fetal hypophysis of the rat: influence of the hypothalamus.

SummaryThe ontogenesis of cells containing polypeptide hormones (ACTH, MSH, LPH, GH and Prolactin) was investigated in the fetal rat hypophysis by immunohistochemistry using the peroxidase-antiperoxidase complex.Corticotrophs, melanotrophs and lipotropic cells were revealed earlier in the pars distalis than in the pars intermedia. In the pars distalis, cells producing LPH were found in the morning of day 15 of gestation using anti-γ- or anti-β-LPH sera, and in the afternoon using anti-α- or β-endorphin sera. Cells containing β-MSH were observed from the afternoon of day 15. The cells stainable with the anti-α-MSH, anti-β-(17-39)ACTH and anti-β-(l-24)ACTH sera appeared on day 16. In the pars intermedia, the cells producing α-MSH, β MSH, α- and β-endorphin, γ and β-LPH were observed in the morning of day 17, while cells containing ACTH were only revealed in the afternoon of the same day of gestation. Based on the treatment of serial paraffin sections with various antisera, it was clearly shown that MSH, ACTH, and LPH occur in the same cells located in the pars distalis as in the pars intermedia.The development of the corticotrophs, melanotrophs and lipotropic cells does not require the presence of the fetal hypothalamus or other central nervous structures. The pituitary glands of 21 day-old fetuses encephalectomized on day 16 showed as many reactive cells as those of the littermate controls.The somatotrophs were first revealed in the pars distalis in the afternoon of day 19. The cells producing prolactin were not observed before day 21 of gestation. On some cases GH and prolactin were found together in one cell. The cytodifferentiation of GH and prolactin cells is apparently not under hypothalamic control.

Immunohistochemical evidence for the presence of melatonin in the pineal gland, the retina and the Harderian gland.

SummaryThe presence of melatonin is demonstrated in the pineal gland, the retina and the Harderian gland in some mammalian and non-mammalian vertebrates, using a specific fluorescence labelled antibody technique. Four different potent antibodies against melatonin have been used and compared. In the pineal gland of hamsters, mice, rats and snakes, specific fluorescence, mostly restricted to the cytoplasm of the cells, is detected in pinealocytes. Fluorescence is also detected in the pineal organ of fishes, tortoises and lizards, but it has not been possible, from cryostat sections of fresh tissue, to assert which kind of cell is reacting (photoreceptor cells or interstitial ependymal cells). In the retina, fluorescence is almost exclusively restricted to the outer nuclear layer. In the Harderian gland of mammals and reptiles, fluorescence is localized in the secretory cells of the alveoli and mostly restricted to the cytoplasm surrounding the nucleus. These results are discussed in relation to the concept of melatonin synthesis at extrapineal sites independent of pineal production.

LHRH-immunoreactive structures in the sheep brain

SummaryNeural structures containing luteinizing hormone-releasing hormone (LHRH) are characterized in adult ewe and female lamb brains. Three anti-LHRH antisera are used in an immunofluorescent or immunoperoxidase method. On our preparations, all three gave the same results, expressed as number of labelled cells (about 2500 in a whole brain). It was found that 95% of the LHRH-immunoreactive cells are located in the preoptico-hypothalamic area, where cell bodies are localized mainly (50%) in the area surrounding the organum vasculosum of the lamina terminalis (OVLT); they are also found in a more anterior section of the medial part of the olfactory tubercle and the medial septum (14%), in a more posterior situation in the anterior and lateral hypothalamus (16%), and in the mediobasal hypothalamus (15%). Fibres originating in various part of the whole preoptico-hypothalamic group reach the OVLT and the median eminence. The remaining cells (5%) and fibres are found in various tel-, di-, and mesencephalic areas.

Comparative distribution of somatostatin, LH-RH, neurophysin, and α-endorphin in the rainbow trout: An immunocytological study

Abstract Using immunofluorescence, evidence of a somatostatin (SRIF)-like antigen has been found in the brain and digestive tract of rainbow trout. In the diencephalon, periventricular SRIF immunoreactive hypendymocytes are located in the region dorsal to the nucleus preopticus (NPO). SRIF immunoreactive perikarya are concentrated anterior to the NPO in the nucleus preopticus periventricularis, scattered in small cells in the nucleus lateralis tuberis (NLT) pars anterior, and in a few cells located in an unnamed nucleus in the dorsomedial hypothalamus. In the pituitary SRIF immunoreactive material is located in the neurohypophysial tissue in the proximal pars distalis. In the gut, SRIF cells have been found in the endocrine pancreas and in the gastric mucosa. Comparatively, material immunoreactive for luteinizing hormone-releasing hormone has the same distribution in the pituitary as SRIF, whereas neurophysin immunoreactivity was found in only the neurophysial tissue of the neurointermediate lobe. A few cells reacting with anti-α-endorphin were seen in the NLT in the pituitary stalk region. All the pars intermedia cells in the neurointermediate lobe react with anti-α-endorphin.

Vertebrate neuropeptide-like substances in the suboesophageal ganglion of two insects: Locusta migratoria R. and F. (Orthoptera) and Bombyx mori L. (Lepidoptera) immunocytological investigation

Abstract A comparative immunocytological investigation carried out through the use of various antisera to vertebrate neuropeptides permitted to show, in one orthopteran and one lepidopteran cells that are neurophysin-vasopressin-like in their antigenicity. In locust suboesophageal ganglion, two paraldehyde fuchsin positive cells (type A cells) have a positive immunofluorescent reaction in presence of anti-neurophysin II and anti-vasopressin antisera. The neurosecretory product of such cells would thus have a dual constitution as in vertebrates: a hormonal peptide (vasopressin-like) linked to a carrier protein (neurophysin-like). In silkworm suboesophageal ganglion, two groups of paraldehyde fuchsin negative cells (three and four cells respectively) contain an α-endorphin-like secretion. This confirms results that we had obtained in another type of lepidopteran and in an oligochete annelid. Thus, there seems to be in the central nervous system of some invertebrates, peptides that have similar immunoreactive groups to the morphinomimetic peptides recently discovered in the vertebrate hypophysis or encephalon.

Immunocytological localization of LH, FSH, TSH and their subunits in the pituitary of normal and anencephalic human fetuses

SummaryImmunostaining with antisera to oLH, hCG, hLH, pLHβ, hFSH, hFSHβ, hTSHα and bTSH was used to delineate the gonadotropic and thyrotropic cells of the human fetal anterior pituitary. Hypophyses from 29 normal fetuses, 3 newborn infants, and 5 totally ancencephalic fetuses were used. Several controls to check for the specificity of the immunocytological reaction were made.In normal fetuses, observations showed that: 1) the α subunit was detected from the eighth week and throughout gestation without sex differences; 2) intact LH was detected during the third month, however, age and sex differences were observed during the fourth and fifth months; 3) intact FSH was detected in female fetuses from the beginning of the fourth month, a sex difference was observed; 4) LH and FSH were detected in the same cells; 5) the thyrotropic cells were detectable from 15 weeks of gestation and their number increased during gestation without sex difference; 6) at birth the gonadotropic cells were scarce and were located in the ventromedian zone of the anterior pituitary, while the thyrotropic cells remained numerous and were located in the dorsomedian zone.In anencephalic fetuses: 1) the α subunit existed at each stage studied; 2) the reaction induced by anti-pLHβ and anti-hFSHβ sera was always very weak regardless of sex or age; 3) the thyrotropic cells were more numerous in comparison to the gonadotropic cells. These data are discussed in terms of the relationship of the hypophysiotropic hypothalamic factors to the appearance and evolution of the glycoprotein hormones and their subunits.

Ontogenesis of the ?-MSH, ?-MSH and ACTH cells in the foetal hypophysis of the rat. Correlation with the growth of the adrenals and adrenocortical activity

SummaryPituitary sections from 15 to 21 day-old rat foetuses have been studied with the immunofluorescence technique, using antibodies anti α-MSH, anti β-MSH and anti β (1–24) ACTH. The first ACTH cells appear on day 17 of pregnancy in the pars distalis of the hypophysis and only on day 18 in the pars intermedia. β-MSH cells have been observed on day 16 in the pars anterior and on day 17 in the pars intermedia, while α-MSH cells appear only on day 18 and exclusively in the pars intermedia. The cytodifferentiation of the β-MSH and ACTH cells occurs in the pars intermedia with about a 24 hour delay in comparison to that of the pars distalis. The first revealed cells are always located in the posterior half of the pituitary gland. The corticostimulating activity of the hypophysis has been tested with the fluorescence intensity of the corticotrophs, the adrenal weight, the adrenal content in corticosterone and the plasma corticosterone level. The fluorescence of the corticotrophs increases on day 18, shows a maximum on day 19 and decreases until term. The adrenal weight rises regularly between day 16 to day 20, thereafter the increase subsides. Adrenal and plasma corticosterone concentrations reach a peak on day 19 of pregnancy. These data suggest that hypophyseal corticostimulating activity is very high between days 18 and 19 and decreases between days 19 and 21.

Immunocytochemical localization of S-100 protein in stellate cells (folliculo-stellate cells) of the anterior lobe of the normal human pituitary.

SummaryWith the use of an anti-human S-100 protein antibody, it was possible to reveal a characteristic cell type in the anterior lobe of the normal human pituitary. These cells, so-called folliculo-stellate cells, were present in all pituitaries studied but their number varied from one gland to another. Immunoreactive cells, isolated or grouped, were arranged close to various secretory granulated cells. Especially by use of double immunoenzymatic labeling, it was evident that these cells are spatially related either to somatotropes, prolactin cells and “corticotropes”, or to glycoprotein-containing cells. Such immunoreactive cells were rare or absent in pseudo-follicular arrangements of secretory granulated cells. Since it is now possible to identify this cell type by light microscopy and since no reliable functional significance is known, it seems more advisable to term this cell type “stellate cell” instead of “folliculostellate cell”.

Immunohistological study of the anterior pituitary gland - pars distalis and pars intermedia - in dwarf mice.

SummaryThis immunohistological study of the anterior pituitary gland in Snell-Bagg dwarf mice demonstrates a total absence therein of somatotropic, prolactin and thyrotropic cells. Gonadotropic, melanocorticotropic, LPH- and endorphin-positive cells are well developed; they appear to be hypertrophied and more numerous than in normal animals.