Some Light- And Electron-Microscopical Observations on the Pars Tuberalis of the Pituitary Gland of the Rabbit

CAMERON, E.; FOSTER, C. L.

doi:10.1677/joe.0.0540505

Cited by 23 publications

(12 citation statements)

References 7 publications

(9 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In various mammalian species, the pars tuberalis (PT) of the pituitary gland is formed by different cell populations, namely: follicular cells, secretory cells identical to those of the pars distalis (PD) and secretory cells apparently specific to the PT (the so-called PT-specific cells) [1,2,3,4]. Although early morphological evidence suggests that the secretion of polypeptides from the fetal rat pituitary gland begins in PT-specific cells [5,6,7], the nature and functional significance of such a secretory material is still an open question.…”

Section: Introductionmentioning

confidence: 99%

Expression of Tuberalin II, α-Subunit of Glycoprotein Hormones and β-Thyrotropin Hormone in the Pars Tuberalis of the Rat: Immunocytochemical Evidence for Pars Tuberalis-Specific Cell Types

Guerra

Rodríguez²

2009

Neuroendocrinology

View full text Add to dashboard Cite

Increasing evidence suggests that the hypophyseal pars tuberalis (PT) plays a key role in the transduction of light/dark (melatonin) information to the endocrine system. It has been shown that PT-specific cells express melatonin receptors and thyrotropin hormone (TSH) subunits. However, these cells do not resemble thyrotrophs or any other of the pars distalis (PD) cells. There is evidence that PT-specific cells secrete a glycoprotein hormone designated as ‘tuberalin’. We have identified a putative tuberalin of 21 kDa (tuberalin II) and have raised antibodies against it. To further investigate whether tuberalin II is a distinct secretory compound of the PT, absorption studies of antituberalin II with TSH or with an extract of the rat PD containing β-TSH, β-luteinizing hormone (LH) and the common α-subunit of glycoprotein hormones (GSU), were performed. Neither of the absorption tests abolished the immunoreactivity of the PT to antituberalin II, suggesting that tuberalin II is different from TSH or the other PD glycoprotein hormones. Double immunofluorescence analyses using antibodies against tuberalin II, β-TSH and GSU revealed that in the developing and adult PT there are 3 populations of PT-specific cells expressing tuberalin II and GSU (type 1), β-TSH and GSU (type 2) and tuberalin II, β-TSH and GSU (type 3). This further indicates that tuberalin II and β-TSH correspond to different compounds and that they may be expressed either by different cells types or coexpressed in a 3rd cell type. The distribution and temporal expression of tuberalin II, β-TSH, β-LH and GSU were investigated in the developing pituitary gland. At E14.5, tuberalin II and GSU were expressed by cells of the PT primordium but not by the PD and pars intermedia primordia. The onset of expression of β-TSH, β-LH and GSU in cells of the PD occurred about 1 day later, further indicating the distinct nature of tuberalin II and supporting the earlier view that the secretion of polypeptides from the fetal rat pituitary gland begins in PT-specific cells.

show abstract

Section: Introductionmentioning

confidence: 99%

Expression of Tuberalin II, α-Subunit of Glycoprotein Hormones and β-Thyrotropin Hormone in the Pars Tuberalis of the Rat: Immunocytochemical Evidence for Pars Tuberalis-Specific Cell Types

Guerra

Rodríguez²

2009

Neuroendocrinology

View full text Add to dashboard Cite

show abstract

“…In chicken, the granules are 180 -250 nm in diameter, and in newt, 185-230 nm (Dellman et al, 1974). In the rabbit, granule diameter is 90 -116 nm, with no presence of glycogen, which constitutes a specific characteristic of this rodent (Cameron and Foster, 1972). In the monkey (macaca fascicularis), the diameter is in the 100 -120 nm range (Bock et al, 2001).…”

Section: Discussionmentioning

confidence: 99%

“…The morphology of the PT has been studied in a number of species: rat (Oota and Kurosomi, 1966), rabbit (Cameron and Foster, 1972), amphibians (Doerr Schott, 1971;Dellman et al, 1974), chicken (Grignon and Guedenet, 1968;Dellman et al, 1974), monkey (macaca fascicularis) (Bock et al, 2001), and guinea pig (Kameda, 1990). While some morphological characteristics are shared between species, others show species-specific variations.…”

Section: Discussionmentioning

confidence: 99%

“…The PT differs from the PD both structurally and morphologically. The PT is a bi-or multilayered region formed by specific secretory cells (the so-called PT-specific cells), folliculostellate cells, and migratory cells coming from the PD (Oota and Kurosomi, 1966;Cameron and Foster, 1972;Stoeckel and Porte, 1984). The diameter of the secretory granules differs according to the species (Dellman et al, 1974) The presence in the PT caudal zone of hormones produced in the PD, particularly LH, FSH, and TSH, has been demonstrated in some species by immunocytochemical techniques (Baker and Yu, 1975;Girod et al, 1980;Asa et al, 1983;Gross, 1984;Böckers et al, 1996).…”

mentioning

confidence: 99%

See 1 more Smart Citation

Ultrastructural and immunocytochemical studies of the viscacha (Lagostomus maximus maximus) pituitary pars tuberalis

et al. 2005

View full text Add to dashboard Cite

The hypophyseal pars tuberalis (PT) has been the focus of numerous studies attempting to understand its physiological role in the reproductive regulation and modulation by the neuroendocrine system. Ultrastructural studies of the PT in a number of species have shown that it consists of a well-developed hypophyseal area with important secretory activity, demonstrated by the abundance of secretory granules in the cytoplasm and the marked blood irrigation. This article describes ultrastructural and immunocytochemical aspects of the PT in viscachas captured in their habitat. The cell types identified were PT-specific cells, agranulated cells, and Folliculostellate cells. PT-specific cells are divided into type I and II. Type I cells have cytoplasms with secretory granules of 150-500 nm diameter. The secretory granules of type II PT-specific cells are 65-200 nm in diameter. Both cellular types exhibit numerous nerve endings on the plasmatic membranes. Agranulated cells exhibit nuclei with lax chromatin, mitochondria, phagosomes, scarce Golgi complex, and rough endoplasmic reticulum. Folliculostellate cells exhibit an irregularly shaped and moderately condensed nucleus. All the described cellular types exhibit deposits of cytoplasmic glycogen. The immunocytochemical study revealed the presence of cells immunostained for LH-␤ and FSH-␤ in the PT caudal zone. ACTH was only detected in the zona tuberalis. No staining was observed with antiprolactin, anti-TSH-␤, and anti-GH sera. Folliculostellate cells exhibited staining with anti-S-100. The results demonstrate that the viscacha PT is a hypophyseal zone with specific cellular types, which exhibits evident secretory activity. The presence of nerve endings suggests neural control of the function of PT cells.

show abstract

“…The PT consists of three clearly distinguishable cell populations; namely, PT-specific cells, follicular cells and secretory cells identical to those of the pars distalis (PD) cells (Wittkowski et al 1999). The PT-specific cells are distinctive endocrine cells that differentiate very early in ontogenesis and that remain active throughout the life-span (Cameron & Foster 1972, Stoeckel et al 1973, 1979, Dellmann et al 1974, Fitzgerald 1979. After Morgan and his coworkers first described the presence of melatonin receptors on the PT cells (Williams & Morgan 1988, Morgan et al 1989 the challenge has been to unfold the functional role of the PT, and to identify and establish the nature of the product(s) secreted by the PT-specific cells.…”

Section: Introductionmentioning

confidence: 99%

Identification, cellular and subcellular distribution of 21 and 72 kDa proteins (tuberalins?) secreted by specific cells of the pars tuberalis

Guerra

Rodríguez

2001

Journal of Endocrinology

View full text Add to dashboard Cite

The cell types of the pars tuberalis (PT) are the follicular cells, the pars distalis cells and the so-called PT-specific cells. The latter are distinct endocrine cells displaying melatonin receptors. Although the nature of the secretory product(s) of the PT-specific cells has not yet been clarified, the function of these cells has started to be unfolded. For practical reasons, previous authors have designated the, as yet, unidentified PT hormone(s) as tuberalin(s). PT-specific cells synthesise the common subunit of the pars distalis glycoprotein hormones, and it has been suggested that tuberalin would correspond to the chain of a specific glycoprotein secreted by these cells. The aims of the present investigation were to identify the compounds secreted by the specific cells of bovine PT, and to establish their cellular and subcellular distribution. For this purpose, proteins secreted into the culture medium of PT explants were separated by electrophoresis and used to raise antibodies. Two of these proteins, with an apparent molecular mass of 21 and 72, generated antibodies (Ab-21 and Ab-72) that differentially immunoreacted with PT-specific cells. These two antibodies were used for immunoblotting of conditioned medium and of PT explants, and for light and electron microscopy immunocytochemistry. In immunoblots, Ab-21 reacted with compounds of 21, 22, 47 and 52 kDa, whereas Ab-72 revealed a compound of 72 kDa only. Ab-72 immunoreactive material corresponded to a protein, here designated as tuberalin I, secreted by a small population of PT-specific cells (type 2 cells), and stored in 140 nm secretory granules. Immunoreactive tuberalin I was missing from bovine pars distalis and from rat PT. The predominant population of PT-specific cells (type 3 cells) secreted and stored, within 280 nm secretory granules, an Ab-21 immunoreactive protein, here designated as tuberalin II. All cells of rat PT immunoreacted with Ab-21. In the cells of bovine and rat PT, immunoreactive tuberalin II was mostly confined to a paranuclear spot; this spot also bound wheat germ agglutinin and reacted with an antibody against the chain of glycoprotein pars distalis hormones.It is suggested that tuberalin II would correspond to the chain of a specific glycoprotein secreted by type 3 PT-specific cells. In bovine PT, the cells displaying immunoreactive tuberalins I and II did not react with any of the antibodies against pars distalis hormones.

show abstract

Some Light- And Electron-Microscopical Observations on the Pars Tuberalis of the Pituitary Gland of the Rabbit

Cited by 23 publications

References 7 publications

Expression of Tuberalin II, α-Subunit of Glycoprotein Hormones and β-Thyrotropin Hormone in the Pars Tuberalis of the Rat: Immunocytochemical Evidence for Pars Tuberalis-Specific Cell Types

Expression of Tuberalin II, α-Subunit of Glycoprotein Hormones and β-Thyrotropin Hormone in the Pars Tuberalis of the Rat: Immunocytochemical Evidence for Pars Tuberalis-Specific Cell Types

Ultrastructural and immunocytochemical studies of the viscacha (Lagostomus maximus maximus) pituitary pars tuberalis

Identification, cellular and subcellular distribution of 21 and 72 kDa proteins (tuberalins?) secreted by specific cells of the pars tuberalis

Contact Info

Product

Resources

About