Histopathology of the pituitary gland in neonatal little (lit) mutant mice.

The pituitary gland in the little (lit) mutant mouse was analyzed with respect to the cytoarchitecture of the pars distalis and the volumetric density of immunoreactive growth hormone (GH) cell granules in neonatal lit/lit and normal C57BL mice. At 8 days postnatally the volume of GH granules/total tissue was significantly less in the lit/lit pars distalis, and the cells were loosely arranged, as compared with the normal pars distalis. In newborn mice a statistically significant difference could not be detected between normal and lit/lit mice with respect to the volumetric density of GH granules; however, differences occurred in the cytoarchitectural organization of the pars distalis. These differences included prominent vascular channels and well-defined cords and clusters of cells in the normal newborn mice, in contrast to indistinct vascular elements and a more diffuse arrangement of cells in lit/lit.     

Growth hormone and prolactin immunoreactivity in the pituitary gland of postnatal little (lit) mice

Homozygous little (lit/lit) mutant mice exhibit a growth lag which is manifested at approximately two weeks postnatally. Functional aspects of the development of pituitary growth hormone (GH) cells and prolactin (PRL) cells were thus analyzed by means of colloidal gold immunocytochemistry at the ultrastructural level in lit/lit mice and their normal counterparts ranging in age from 5 days postnatally to adulthood. In the adult normal and lit/lit pituitaries, secretory granules in GH cells and PRL cells showed a positive immunoreaction to their respective antisera, as did granules in both cell-types at 5 days postnatally. By 14 days some GH cells in lit/lit pituitaries appeared to be less densely populated with granules than GH cells in normal pituitaries, but a positive immunoreaction continued to occur even in sparsely granulated GH cells. PRL cells showed ultrastructural features in lit/lit pituitaries which were similar to those in normal mice, and immunoreactivity was present at all stages examined. The results indicate that since differences in granule reactivity were not evident between lit/lit and normal GH cells, despite ultrastructural morphologic differences which were present by 14 days postnatally, manifestations of the defect in lit/lit may be primarily quantitative in terms of numbers of granules and/or numbers of GH cells. With respect to PRL cells, neither morphologic nor functional aberrations could be observed; thus, a deficit in PRL hormone production might be the result of a more subtle defect than that in GH cells.     

Postnatal development of growth hormone and prolactin cells in male and female rat pituitary. An immunocytochemical light and electron microscopic study

Localization and ultrastructural maturation of prolactin (PRL) and growth hormone (GH) cells were studied in pituitaries from neonatal, immature (4-6 weeks old), and adult rats (2-3 months old) by light and electron microscopic immunocytochemistry. The distribution pattern of these cells did not change with age. Both cell types were concentrated laterodorsally, with PRL cells adjacent to the intermediate lobe and GH cells nearer the center of the pars distalis. Labeling density of the immunogold reaction was highest for both hormones in immature rats. In neonatal and immature rats, one PRL cell type with granules 200 nm in diameter was present. In adult rats, two types of PRL cells were present: one containing polymorphous granules measuring about 500 nm (prevalent in female rats), the other with spherical granules about 200 nm (prevalent in male rats). No changes were detected in GH cells during maturation.     

Fine structure of somatotrophs and mammotrophs in the pituitary pars distalis of the little (lit) mutant mouse

The cellular pathology and postnatal differentiation of somatotrophs and mammotrophs in the pars distalis of little (lit/lit) and normal (+/+; lit/+) mice were studied by means of electron microscopy. The results indicate that in little the pituitary at birth contains recognizable somatotrophs and mammotrophs; however, between 14 and 24 days of age a contrast between little and normal becomes conspicuous with respect to the somatotrophs. Little somatotrophs are less heavily populated with granules, have granules of smaller size, and show less developed organelles than do normal somatotrophs at comparable stages. Beyond 24 days the little somatotrophs become more difficult to locate, and those that do occur show a minimal increase in complexity from that present at 14 days. In contrast, the mammotrophs in little are similar in appearance to normal mammotrophs and show increasing complexity as development proceeds, often sending forth cellular processes between neighboring cells, as do normal mammotrophs.     

Immunocytochemical analysis of somatotrophs and mammotrophs in the pars distalis of postnatal dwarf (dw) mutant mice

Summary The postnatal differentiation of somatotrophs and mammotrophs in the pars distalis of normal and dwarf (dw/dw) mice was analyzed by means of immunocytochemistry at the electron-microscopic level. Thin sections of Araldite-embedded pituitaries from postnatal mice ranging in age from 2 days to 3–4 months were exposed to antigrowth hormone serum (anti-GH) or to anti-prolactin serum (anti-PRL) and were processed immunocytochemically by means of the colloidal-gold technique. In the normal adult pars distalis, somatotrophs reacted strongly with antiGH, and mammotrophs showed a positive anti-PRL reaction. In the dwarf adult, the granulated cells were unreactive with either anti-GH or anti-PRL. However, at 6 days postnatally, some cells in the dwarf pars distalis showed a positive reaction with anti-GH, though the reaction was not as strong as in the 6-day normal pars distalis. The 6-day dwarf was only faintly reactive with anti-PRL, and by 14 days the dwarf was unreactive with anti-GH as well as anti-PRL, in contrast to the strong positive reactivity to these two antisera in the normal 14-day pars distalis.Supported by USPHS grant HD12308     

Fine structure of the adenohypophysis in immature sockeye salmon,Oncorhynchus nerka

Summary The ultrastructure of the secretory cells of the adenohypophysis of juvenile sockeye salmon was investigated. Pituitary glands were collected from immature fish transferred experimentally to sea water and subsequently returned to fresh water. The rostral pars distalis contained three cell types: ACTH cells, prolactin cells, and non-secretory cells. The prolactin and non-secretory cells were joined together in the form of follicles by desmosomes and they both had cilia and microvilli projecting into the follicle lumen. Various follicular structures such as lumen, multivesicular structures, and peripheral basement membrane are discussed as possible sites of prolactin cell granule release. The columnar ACTH cells were found at the junction of the rostral pars distalis and the neurohypophysis. The cytoplasmic granules in these cells were characteristically separated from their limiting membrane by a clear space. Multivesicular structures were also found in association with this cell type. The caudal pars distalis also contained three cell types: one acidophil (putative somatotrop) and two basophils (putative thyrotrops and gonadotrops), all of which were similar to those described in adult fish. The pars intermedia contained only one cell type. They appeared to be active cells and were characterized by containing membrane-bounded granules similar to those found in the ACTH cells. Changes in ambient salinity had no apparent effect on any cell type described.The work was supported by a grant in aid of research from the National Research Council of Canada. We wish to thank Mr. R. Lindsay, Mr. C. Cooper, and Mr. G. Longworth for their technical assistance. We would also like to thank Mr. S. Killick of the International Pacific Salmon Fisheries Commission for his assistance in the collection of fish and Dr. H. Cook for his helpful discussion of the project. This paper is No. 058 in the University of Guelph Migration Series.     

CXCL14-like immunoreactivity in growth hormone-containing cells of urodele pituitaries

Immunohistochemical techniques were employed to investigate the distribution of a chemokine, namely, CXCL14-like immunoreactivity in the axolotl (Ambystoma mexicanum) and Japanese black salamander (Hynobius nigrescens) pituitaries. CXCL14-immunoreactive cells concentrated at an area of the pars distalis adjacent to the pars intermedia. We found that these cells correspond to the cells immunoreactive to an antibody against rat growth hormone (GH). Immunoelectron microscopy indicated that the CXCL14-like substance and GH coexisted on the secretory granules in the axolotl pituitary. Western blot analysis of axolotl pituitary extracts revealed the anti-human CXCL14 antibody labeled an approximately 16.6-kDa band that was not labeled by the anti-GH antibody. The CXCL14-like substance in the pars distalis may participate in GH functions in these species.     

Immunocytochemical studies on the pituitary pars distalis of the Japanese long-fingered bat,Miniopterus schreibersii fuliginosus

Summary Immunocytochemical studies were performed to describe the characteristics of cell types and their distribution in the pars distalis of Japanese long-fingered bat, Miniopterus schreibersii fuliginosus, collected at various stages of the reproductive cycle. Six distinct cell types have been identified in the pars distalis by the unlabeled immunoperoxidase technique and by the ABC method. Growth hormone (GH) and prolactin (PRL) cells were immunostained with antisera against chicken GH and ovine PRL. The GH-immunoreactive cells were round or oval orangeophilic cells distributed throughout the pars distalis with prominent aggregation in the posterolateral region. The PRL cells were pleomorphic carminophilic cells that occurred in small groups within the central and dorsocaudal regions of the pars distalis. They were sparsely distributed in the central region of the pars distalis in the hibernating bats, but increased significantly in the pregnant and lactating bats. The adrenocorticotropic (ACTH) cells were large round or polygonal amphophilic cells in the rostroventral and ventrolateral regions of the pars distalis. The thyrotropic (TSH) cells were small rounded or polygonal and distributed mainly in the ventrolateral region of the pars distalis. Luteinizing hormone (LH) and follicle-stimulating hormone (FSH) cells were identified immunocytochemically with antisera against the specific beta subunits of ovine LH and rat FSH. There were two populations of LH and FSH cells, one aggregated in the zona tuberalis and the other scattered singly throughout the rest of the pars distalis. The aggregated cells were immunoreactive with both antisera directed to LH and FSH, while scattered cells were reactive solely with antiserum to either LH or FSH and exhibited seasonal variations. In females, the proportional volume of the pars distalis occupied by LH cells was significantly reduced during pregnancy and lactation. No evidence of involution was observed in pars distalis cells except for PRL cells in males or females during hibernation.     

Immunocytochemical identification and ontogeny of adenohypophyseal cells in a cave fish,Phreatichthys andruzzii (Cypriniformes: Cyprinidae)

The morphogenesis of the pituitary gland and the chronological appearance of adenohypophyseal cells were investigated for the first time in the Somalian cave fish Phreatichthys andruzzii by immunocytochemistry. The adult adenohypophysis contained: a rostral pars distalis, with prolactin (PRL) cells arranged in follicles and adrenocorticotropic (ACTH) cells, a proximal pars distalis with somatotropic (GH), β‐thyrotropic (TSH), β‐gonadotropic type I (FSH) and type II (LH) cells and a pars intermedia with α‐somatolactin (SL), α‐melanotropic (MSH) and β‐endorphin (END) cells. All regions were deeply penetrated by neurohypophyseal branches. At hatching (24 h post‐fertilization) the pituitary was an oval cell mass, close to the ventral margin of diencephalon. The first immunoreactive cells appeared as follows: PRL at 0·5 days after hatching (dah), GH and SL at 1·5 dah, END at 2 dah, TSH, ACTH and MSH at 2·5 dah, FSH at 28 dah and LH at 90 dah. The neurohypophysis appeared at 5 dah and branched extensively inside the adenohypophysis at 130 dah, but there was no boundary between rostral pars distalis and proximal pars distalis at this stage. The potential indices of prolactin and growth hormone production increased until 28 and 60 dah, respectively. The potential index of growth hormone production correlated positively with total length. Activity of PRL and GH cells, measured as ratio of cell area to nucleus area, was significantly higher in juveniles than in larvae.     

Nuclear uptake and retention of androgen by the pituitary gland of the hamster and the rat

Summary Castrated adult male hamsters and castrated adult female rats were injected with either 0.2 g (hamsters) or 0.5 g (rats) of ³H-dihydrotestosterone (107 Ci/mmole)/100 grams body weight and killed 11/2 h later. The pituitary glands were removed and processed for both autoradiography and immunocytochemistry (hamster) or only autoradiography (rats). Localization of the androgen was found in 10–15% of the cells of the pars distalis in both species. Only cells that stained for luteinizing hormone (LH) in the hamster's pars distalis concentrated the androgen. Also cells in both the pars intermedia and pars nervosa (1–5%) concentrated the androgen in both species. Although the number of cells that concentrated the androgen in the pars intermedia and pars nervosa was small, this finding may be related to recent physiologic data that suggest that the gonadal steroids may play a role in regulating water retention and natriuresis.This study was supported by USPHS Research Career Development Award KO4NS0000164 (P.J. Sheridan) and USPHS Grants No. 1 RO1 NS12933, P30 HD10202 and HD 10914     

Histophysiological and immunocytochcmical study on the nature of the thyrotrops in the pituitary of immature rainbow trout,Salmo gairdneri

Alcian blue- and periodic acid-Schiff-positive "granular basophils" with electron-dense granules +/- 160 nm in diameter, and weakly developed irregular cisternae of the granular endoplasmic reticulum (GER) are present in the rostral pars distalis (RPD) and the proximal pars distalis (PPD) of immature rainbow trout. They all react with antisalmon alpha beta-gonadotropin. However, only granular basophils in the caudal RPD and the rostro-dorsal PPD, often bordering on and sometimes surrounded by neurophypophysial tissue, react with anti-human beta-TSH. These cells, considered as the source of thyrotropin, show degranulation and dilatation of the GER-cisternae in fish treated with potassium perchlorate. The thyroids of the goitrogen-treated animals had relatively numerous small follicles with a high epithelium. The remaining granular basophils are gonadotrops.     

Adenohypophysial cell types in the lamprey pituitary: current state of the art

Adenohypophysial cell types in the pituitary of adult sea lampreys, Petromyzon marinus, was localized by means of immunocytochemical and lectin cytochemical techniques. At least four types of adenohypophysial hormone cells are present in the pituitary of adult sea lampreys. The first type of cell is ACTH-like and occupies most parts of the rostral pars distalis (RPD), but a few scattered ACTH-like cells are also present in the proximal pars distalis (PPD). The second type of cell is MSH-like and occupies the whole pars intermedia. The third type of cell is GH/PRL-like and occupies the dorsal half of the PPD. These GH/PRL-like cells were initially detected by heterologous immunocytochemistry using antibodies to salmon GH, salmon PRL and blue shark GH, after hydrated autoclave pretreatment of sections. Later, by use of an antiserum raised against a synthetic peptide corresponding to the partial sequence of lamprey GH/PRL, the same cells as those containing GH/PRL-like immunoreactivity were stained positively. Similarity of the topographic distributions between lamprey GH/PRL-like cells and gnathostome fish GH cells in the pituitary suggests that GH/PRL-like cells in the lamprey may be GH cells. The last type of cell is GTH-like and occupies the ventral half of the PPD. Although GTH has not yet been isolated from the lamprey pituitary, our immunocytochemical data suggest that GTH-like material in the sea lamprey pituitary is more closely related to mammalian-like LH, rather than to FSH or TSH. These four types of adenohypophysial cells occupy most parts of the lamprey adenohypophysis and indeed there is little room for TSH or PRL cells. Thus, the present study further suggests that GH and LH-like GTH are ancestral forms of GH/PRL/SL family and glycoprotein hormones, respectively.     

Immunocytochemical effects of thyroxine stimulation on the adenohypophysis of dwarf (dw) mutant mice

The effects of dietary thyroxine on the immunoreactivity of cells in the pars distalis of the adenohypophysis in dwarf (dw/dw) mice were determined by ultrastructural immunocytochemistry. In nontreated dwarfs only adrenocorticotropic hormone (ACTH) cells and luteinizing hormone (LH) cells showed positive reactions to their respective antibodies, whereas no cells showed immunoreactivity to antibodies to growth hormone (GH), thyroid-stimulating hormone (TSH), or prolactin (Prl). In dwarfs supplemented postnatally with dietary thyroxine for 9 wks, the treatment failed to produced immunoreactive GH, TSH or Prl cells. However, LH cells became more prominent and fully developed, with denser concentrations of immunoreactive particles overlying the secretory granules than occurred in nontreated dwarfs. In thyroxine-treated dwarfs, ACTH cells were similar in ultrastructural features and immunoreactivity to those in nontreated dwarfs.     

Effect of decreased environmental salinity on growth hormone cells in the gilthead sea bream (Sparus aurata)

The effect of decreased environmental salinity on growth hormone producing cells (GH cells) of the adenohypophysial proximal pars distalis has been studied in the gilthead sea bream ( Sparus aurata L.) adapted to sea water (SW, 980 mosmol kg ⁻¹) and brackish water (BW, 200 mosmol kg ⁻¹). A combined immunocytochemical, morphometric and electron microscopic study was carried out. GH cells offish adapted to BW occupied a greater hypophysial volume (about 21% of the total hypophysial volume in BW, 17% in SW) and had a larger nuclear area (mean 16 μm² in BW, 13 μm² in SW) than GH cells of SW-adapted fish. The immunoreactivity against a salmon GH-antiserum was lower in BW (mean optical density 142 in BW, 159 in SW). Ultrastructural characteristics of GH cells of BW-adapted fish were distended rough endo-plasmatic reticulum and large secretory granules (about 216 nm in diameter for BW, 209 nm in SW). Volumetric, densitometric and ultrastructural evidence suggested that the synthesis and release of GH were activated in S. aurata adapted to hypo-osmotic environment.     

Electron-microscopic investigation of the innervation of the pars distalis of the hypophysis in adult Rana temporaria L.

Summary In the pars distalis of the hypophysis of adult Rana temporaria, three types of nerve-fiber profiles were found at two distinct sites, in both lateral parts of the bordering regions of the anterior lobe with the intermediate lobe of the hypophysis. The first type of nerve-fiber profile consists of bundles of very fine axonal elements (diameter: <0.7 m). The second type is formed by larger nerve fibers (diameter up to 4 m) containing a few neurosecretory granules of approximately 100 nm. The third type of nervefiber profile resembles the second type but these nerve fibers make synaptoid contacts on at least two different types of glandular cells. The possible functional significance of these nerve fibers in the pars distalis is discussed.No nerve fibers were found (1) in the central part of the bordering region of the pars distalis with the intermediate lobe, (2) at the bordering region with the median eminence and (3) with the neurohypophysial stalk, and (4) in all other parts of the pars distalis.     

rdw rats, a new hereditary dwarf model in the rat

A new hereditary dwarf mutation was found in Csk: Wistar-Imamichi rat breeding colony. The mutant rats and control normal rats were studied with clinical, genetical and histological examination. The result showed that the present mutation was inherited in autosomal recessive trait (gene symbol; rdw) and was provoked with the hypoplasia of pars distalis (anterior pituitary), in particular the secretory cells of GH, PRL and TSH. The characteristics of the present mutant (rdw) was very similar to dw mouse, and was usefull for endocrinological research as an animal model of human pituitary dwarfism.     

Postnatal development of somatotrophs and mammotrophs in the pars distalis of the C57BL mouse

Summary The pars distalis of the pituitary gland of the C57BL mouse was studied by means of electron microscopy during postnatal stages of males ranging in age from newborn through 24 days, with particular emphasis on the somatotrophs and mammotrophs. During this period, growth curves were plotted in order to correlate postnatal growth patterns with the state of differentiation of the somatotrophs in the pars distalis. In the newborn, the somatotrophs show well developed organelles, including rough endoplasmic reticulum and Golgi complexes. These cells are not as densely packed with granules as the adult somatotrophs; however, from days 5 through 24, they show a progressive accumulation of granules. Although mammotrophs are scarce in the newborn, they are readily distinguishable in the pars distalis at 5 days. Male mice in small litters show a progressive increase in body weight between birth and 11–12 days, at which time the rate slackens until 18–19 days when the rate again increases. Growth curves for mice from large litters are similar to those from smaller litters, except that the transitory decrease in rate is more prominent.Supported by NIH grant no. HD12308 from the National Institute of Child Health and Human Development, USPHSThe authors wish to thank Pratima Ganguly for technical assistance     

Glycoconjugate localization with lectin and PA-TCH-SP cytochemistry in rat hypophysis

Glycoconjugates were localized by light microscopy with lectin-peroxidase conjugates and by electron microscopy with the periodic acid-thiocarbohydrazide-silver proteinate (PA-TCH-SP) sequence in immunocytochemically or morphologically identified cell types in rat pituitary. Lectin histochemistry demonstrated sialic acid and glycoconjugates with N-glycosidically linked oligosaccharides in gonadotrophs, thyrotrophs, and corticotrophs. Galactose penultimate to sialic acid was observed mostly in gonadotrophs. The terminal galactose-N-acetylgalactosamine disaccharide was detected in a few gonadotrophs and in a moderate number of mammotrophs. Fucose was localized in only corticotrophs with two fucose-binding lectins and in thyrotrophs with another. Several different monosaccharides were seen in glycoconjugates in melanotrophs and in Herring bodies. Melanotrophs displayed heterogeneous staining with fucose-binding lectins. A small number of nonsecretory cells were also visualized in the pars distalis by virtue of their glycogen content. PA-TCH-SP staining revealed complex carbohydrates in secretory granules and some Golgi cisternae in all types of hormone-producing cells in the pars distalis except for the somatotrophs. Melanotrophs of pars intermedia exhibited stained secretory granules and irregular dense bodies containing a stained meshwork. Corticotrophs of the pars distalis lacked the latter bodies, although they form the same glycoprotein precursor hormone as melanotrophs. Lectin conjugates and the PA-TCH-SP sequence stained some groups of secretion granules in Herring bodies, possibly representing vasopressin-containing granules as well as other cell types in the pars nervosa.     

An immunocytochemical study of the pituitary gland of the white seabream (Diplodus sargus)

The adenohypophysis of the white seabream (Diplodus sargus) was studied using histochemical and immunocytochemical techniques. The adenohypophysis was composed of rostral pars distalis, proximal pars distalis and pars intermedia. Prolactin (anti-chum salmon prolactin positive) and adrenocorticotropic (anti-human ACTH positive) cells were found in the rostral pars distalis. Prolactin cells were organized into follicles, while ACTH cells were arranged in cords around neurohypophyseal tissue branches that penetrated the rostral pars distalis. In the proximal pars distalis, somatotropic (anti-chum salmon and anti-gilthead seabream growth hormone positive), gonadotropic (anti-chum salmon -gonadotrophin II and anti-carp -gonadotrophin II positive, but anti-chum salmon -gonadotrophin I negative) and thyrotropic (anti-human -thyrotropin positive) cells were observed. Growth hormone cells were restricted to the dorsal and ventral part of the proximal pars distalis. They were clustered or surrounded the neurohypophyseal branches. Only one type of gonadotrophin cell was identified and they were clustered or isolated in the proximal pars distalis. Scattered groups of thyrotropin cells were located throughout the proximal pars distalis. In the pars intermedia somatolactin (anti-chum salmon and anti-gilthead seabream somatolactin positive) and melanotropic (anti--melanotropic hormone positive) cells were localized. In addition, gonadotrophin cells surrounded the pars intermedia or distributed evenly between somatolactin and melanotropic hormone cells. Somatolactin cells were periodic acid-Schiff negative and surrounded the neurohypophyseal branches intermingled with melanotropic cells. These cells were also immunoreactive to anti-human ACTH antiserum.     

Effects of Methallibure (ICI 33,828) on the pars distalis of pituitary,testis and thumb pad of the green frog,Rana esculenta L.

Summary The influence of ICI compound 33,828 (1--methylallylthiocarbamoyl-2-methylthiocarbamoylhydrazine = Methallibure) on the pars distalis of pituitary, testes and thumb pads was investigated in the intact adult male green frog, Rana esculenta. Methallibure affected the gonadotropic basophils (particularly the B2 cells) of the pars distalis, which showed varying degrees of degranulation and underwent a notable decrease in their percentage. Within the testis this compound caused the arrest of spermatogenesis. The most uniform effect of Methallibure was observed in the thumb pads, which invariably showed regression of the epidermis and glandular epithelium. No histological changes occurred in the thyroid and adrenal glands and the B1 and A1 cells of the pars distalis remained unchanged cytologically. It is concluded, in concordance with the available data, that Methallibure is a non-steroidal antigonadotropic compound. The important question about its mode of action has been brought into discussion.Work supported by the National Research Council of Italy, and the Population Council (Grant No. M70.082 C) of New York.