Thyroid-stimulating Hormone Cells Research Articles

Immunocytochemical identification and localization of the different cell types in the pituitary of the seabass ( Dicentrarchus labrax)

Antisera raised against chum salmon prolactin (PRL), trout growth hormone (GH), mammalian adrenocorticotropic hormone (ACTH), thyroid-stimulating hormone (TSH), luteinizing hormone (LH), and α-melanophore-stimulating hormone (α-MSH) were used to localize PRL, GH, ACTH, gonadotropic, TSH, and MSH cells in the hypophysis of the teleost Dicentrarchus labrax using the unlabeled peroxidase anti-peroxidase method. In the rostral pars distalis, ACTH cells stained very intensively with anti-ACTH; so did the MSH cells in the pars intermedia. The prolactin cells stained very specifically with anti-prolactin without staining the growth hormone cells. In the proximal pars distalis anti-GH, anti-TSH β, and anti-LH stained selectively the corresponding cells; with these antisera no cross-reaction with any other cell type was observed. Anti-α-MSH only stained cells in the pars intermedia. Some cells in the pars intermedia did not react at all; these could correspond to the PAS-positive cells. A characteristic feature was positive staining with anti-LH in some cell groups encircling the pars intermedia, indicating the fact that in the seabass some cells of the proximal pars distalis surround the pars intermedia.

Immunohistochemistry of the hypothalamic neuropeptides and anterior pituitary cells in the Japanese quail.

The pars distalis of the avian adenohypophysis consists of well-defined cephalic and caudal lobes which are distinct in their cellular constituents. Immunocytochemical investigations on the pituitary hormones of the pars distalis of the Japanese quail reveal five types of secretory cells, adenocorticotropin (ACTH) cells, prolactin (PRL) cells, thyroid-stimulating hormone (TSH) cells, growth hormone GH (STH) cells, and FSH/LH (gonadotropic) cells. The ACTH cells, TSH cells, and PRL cells are restricted to the cephalic lobe, and GH (STH) cells are confined to the caudal lobe, while FSH/LH cells are distributed throughout the cephalic and caudal lobes. The median eminence of birds has distinct anterior and posterior divisions, each with different neuronal components. The avian hypophysial portal vessels also consists of two groups, anterior and posterior. The peculiar arrangement and distribution of the avian hypophysial portal vessels are possibly related to the distribution of neuropeptides in the two divisions of the median eminence and to the cytological and functional differentiation of two lobes of the pars distalis. The localization of perikarya and fibers containing luteinizing hormone releasing hormone (LHRH), somatostatin, vasotocin, mesotocin, corticotropin-releasing factor (CRF), vasoactive intestinal polypeptide (VIP), glucagon, metenkephalin, and substance P in the hypothalamus and median eminence of the Japanese quail has been investigated by means of immunohistochemistry using antisera against the respective neuropeptides. LHRH-, somatostatin-, VIP-, met-enkephalin-, and substance P-immunoreactive fibers are localized in the external layer of the anterior and posterior divisions of the median eminence, while CRF- and vasotocin-reactive fibers are demonstrated only in the external layer of the anterior division of the median eminence. The metenkephalin fibers are thicker in the anterior median eminence but the substance P fibers are more abundant in the posterior division. Mesotocin fibers occur only in the internal layer of the median eminence and neural lobe.

Immunocytochemical study of growth hormone, prolactin, and thyroid-stimulating hormone in the adenohypophysis of the sea lamprey, Petromyzon marinus L., during its upstream migration

Immunoreactivity to growth hormone (GH), prolactin (PRL), and thyroid-stimulating hormone (TSH) was found in the adenohypophysis of the sea lamprey, Petromyzon marinus L., during its upstream migration, by immunoperoxidase techniques with antisera to mammalian pituitary hormones. Cross-reactivity to GH and PRL was found in two different cell populations in the proximal pars distalis. Specific immunostaining for GH and PRL was absent in other parts of the lamprey pituitary. Immunoreactive TSH cells were located only in the rostral pars distalis, and corresponded in shape and size to the large basophils in this region of the lamprey pituitary. These results suggest that mammalian-like GH, PRL, and TSH are produced in the pituitary of the lamprey.

Ultrastructural immunocytochemical characterization of the thyrotroph in rat and human pituitaries.

The beta chain of thyroid stimulating hormone (TSH) was localized in normal rat and human pituitaries with the unlabeled antibody--peroxidase-antiperoxidase complex technique and antisera to rat or bovine TSH beta. Araldite embedded tissues, immunoreactivity of TSH was best preserved after fixation with 1% glutaraldehyde or picric acid formaldehyde. In the TSH cells, the immunocytochemical stain was located on granules. However, there was a variation in staining of individual granules, and among the population of granules. Rat TSH cells were ovoid or angular to stellate, and contained granules ranging in size from 60-175 nm. The human TSH cell was polyhedral, and contained scattered granules of 150-300 nm diameter. In both species, granule distribution was either in 1-2 rows at the periphery, or scattered throughout the cytoplasm with some concentration in cytoplasmic processes. TSH cells in female rats in estrous contained more granules than those of other stages. TSH cells were distinguished from adrenocorticotropic hormone cells and luteinizing hormone cells on the basis of granule size and distribution, and cell shape.

An immunocytochemical study of TSH beta storage in rat thyroidectomy cells with and without D or L thyroxine treatment.

Binding sites to the beta chain of thyroid stimulating hormone (TSH) were localized in pituitaries of thyroidectomized rats. Immunocytochemical staining was observed in hypertrophied TSH cells ("thyroidectomy cells") and primarily located in dilated rough endoplasmic reticulum. Staining was also found on the few secretory granules and on some of the intracisternal granules. Some of the thyroidectomy cells stained intensely, while others exhibited very little staining. When thyroidectomized rats were treated with thyroxine 4 days before death, the TSH cells contained more secretory granules, and the intracisternal granules were larger and more numerous. L-thyroxine was 10 times as potent as D-thyroxine in promoting the build-up of granules. Both types of granules stained intensely.

Immunocytochemistry of the pituitary glycoprotein hormones.

The storage sites of the pituitary glycoprotein hormones were identified with the use of electron microscopic immunocytochemical techniques and antisera to the beta (beta) chains of follicle-stimulating hormone (FSH), luteinizing hormone (LH) and thyroid-stimulating hormone (TSH). The TSH cells in normal rats is ovoid or angular and contains small granules 60-160 nm in diameter. In TSH cells hypertrophied 45 days after thyroidectomy, staining is in globular patches in granules or diffusely distributed in the expanded profiles of dilated rough endoplasmic reticulum. The gonadotrophs (FSH and LH cells) exhibited three different morphologies. Type I cells are ovoid with a population of large granules and a population of small granules. Staining for FSHbeta or LHbeta was intense and specific only in the large granules (diameter of 400 nm or greater). Type II cells are angular or stellate and contain numerous secretory granules averaging 200-220 nm in diameter. They predominate during stages in the estrous cycle when FSH or LH secretion is high. Type III cells look like adrenocorticotropin (ACTH) cells in that they are stellate with peripherally arranged granules. They generally stain only with anti-FSHbeta and their staining can not be abolished by the addition of 100 ng ACTH. In preliminary quantitative studies of cycling females, we found that on serial sections FSH cells and LH cells show similar shifts to a more angular population of cells during stages of active secretion. However, the shifts are not in phase with one another. Furthermore, there are at least 1.5 times more FSH cells than LH cells at all stages of the cycle. Our collection of serial cells shows that some cells (usually type I or II) stain for both gonadotropic hormones, whereas others (usually type II or III) contain only one.