Cytodifferentiation of Wulzen's cone of mature male sheep hypophysis cerebri with special emphasis on its parenchymal correlations with the adjacent pars distalis, pars intermedia and pars nervosa.

Background: Hypophysis cerebri is considered the master endocrine gland as it plays a critical role in influencing and controlling the vitality of other endocrine organs via several hormones secretion. Aim: The present study was performed to clarify the localization of Wulzen's cone (WC) within sheep hypophysis and cytodifferentiation of the glandular cells filling cone parenchyma with particular emphasis on the cone correlations with adjacent pars distalis (pd), pars intermedia (pi), and pars nervosa (pn). Methods: Pituitaries were collected and processed histologically, then subjected to different combinations of special stains; Br-AB- OFG., PFA-AB-PAS-OG., PAS-Orange G., Orange G- Acid Fuchsin- Light Green, Bielschowsky technique, Masson's trichrome & Gomori's reticulin. Results: A sagittal section through the pituitaries revealed a well-developed cone of glandular cells protruding from the pi like a tongue plate towards the hypophyseal cleft in the neighborhood of the pd and behind the pn. Resembling the pd, various glandular cells were distinguished in the cone; chromophobes and chromophils of acidophils & basophils. The cone is mainly formed from acidophils intermingled with the chromophobes. Meanwhile, basophils were primarily localized at the most anterior & posterior parts of the cone. In front of the cone, pd were localized, resembling a wing-shaped and filled with several categorized glandular cells; chromophobes and chromophils. Upper to the cone, pi were localized and composed mainly of weakly basophilic cuboidal or polygonal cells arranged in parallel cords or follicles. Behind the cone, pn was localized as a ventral outpouching of the brain floor-like water drop. Unlike the cone, it was devoid of any glandular secretory cells or nerve cells but consisted mainly of unmyelinated nerve fibers, herring bodies, and pituicytes. Conclusion: WC is present and well-developed in sheep adenohypophysis. Various glandular cells were distinguished, filling the cone, chromophobes, and chromophils of acidophils & basophils that were typically similar to the glandular cells of pd but with different distributions.

Structural Reconstruction of the Perivascular Space in the Adult Mouse Neurohypophysis During an Osmotic Stimulation.

Oxytocin (OXT) and arginine vasopressin (AVP) neuropeptides in the neurohypophysis (NH) control lactation and body fluid homeostasis, respectively. Hypothalamic neurosecretory neurones project their axons from the supraoptic and paraventricular nuclei to the NH to make contact with the vascular surface and release OXT and AVP. The neurohypophysial vascular structure is unique because it has a wide perivascular space between the inner and outer basement membranes. However, the significance of this unique vascular structure remains unclear; therefore, we aimed to determine the functional significance of the perivascular space and its activity-dependent changes during salt loading in adult mice. The results obtained revealed that pericytes were the main resident cells and defined the profile of the perivascular space. Moreover, pericytes sometimes extended their cellular processes or 'perivascular protrusions' into neurohypophysial parenchyma between axonal terminals. The vascular permeability of low-molecular-weight (LMW) molecules was higher at perivascular protrusions than at the smooth vascular surface. Axonal terminals containing OXT and AVP were more likely to localise at perivascular protrusions than at the smooth vascular surface. Chronic salt loading with 2% NaCl significantly induced prominent changes in the shape of pericytes and also increased the number of perivascular protrusions and the surface area of the perivascular space together with elevations in the vascular permeability of LMW molecules. Collectively, these results indicate that the perivascular space of the NH acts as the main diffusion route for OXT and AVP and, in addition, changes in the shape of pericytes and perivascular reconstruction occur in response to an increased demand for neuropeptide release.

The Infundibular Recess Passes through the Entire Pituitary Stalk.

BACKGROUND AND PURPOSE: The infundibular recess (IR), commonly illustrated as a V-shaped hollow in the sagittal view, is recognized as a small extension of the third ventricle into the pituitary stalk. The precise morphology of the human IR is unknown. The present study sought to delineate the morphology of the IR using magnetic resonance imaging. MATERIALS AND METHODS: Subjects included 100 patients without acute cerebral infarcts, intracranial hemorrhage, intrasellar or suprasellar cysts, hydrocephalus, inflammatory disease, or brain tumors. Patients with symptoms of increased intracranial pressure, intracranial hypotension, or pituitary dysfunction were excluded. Thin-sliced, seamless T2-weighted sequences involving the optic chiasm, entire pituitary stalk, and pituitary gland were performed in axial and sagittal planes for each patient. The numbers of slices delineating the pituitary stalk and IR were recorded from the axial images and quantified as ratios. RESULTS: The pituitary stalk consistently appeared as a styloid- or cone-shaped structure with variable inclinations toward the third ventricle floor. The IR was delineated as a smoothly tapering, tubular extension of the third ventricle located in the central portion of the pituitary stalk. In 81 % of patients, the IR passed through the entire length of the pituitary stalk and reached the upper surface of the pituitary gland, which was identified in 40 % of the midsagittal images. CONCLUSIONS: The IR is a cerebrospinal fluid-filled canal passing through the center of the pituitary stalk and connects the third ventricle to the pituitary gland. It may function in conjunction with the pituitary gland.

A membranous structure separating the adenohypophysis and neurohypophysis: an anatomical study and its clinical application for craniopharyngioma.

OBJECT This study aimed to identify the membranous septation between the adeno- and neurohypophysis. The clinical impact of this septation in the surgical removal of infradiaphragmatic craniopharyngioma (Id-CP) is also clarified. METHODS The sellar regions from 8 fetal and 6 adult cadavers were dissected. After staining first with H & E and then with picro-Sirius red, the membranous structures were observed and measured under normal light and polarization microscopy. The pre- and postsurgical images and intraoperative procedures in 28 cases of childhood Id-CP were reviewed and analyzed. RESULTS There is a significant membranous septation (termed the adenoneurohypophysis septation [ANHS]) lying behind the intermediate lobe to separate the adeno- and neurohypophysis. The average thicknesses are 21.9 ± 16.9 µm and 79.1 ± 43.2 µm in fetal and adult heads, respectively. The median segment of the septation is significantly thicker than the upper and lower segments. The ANHS extends from the suprasellar pars tuberalis to the sellar floor, where it is fused with the pituitary capsule. During Id-CP surgery performed via a transcranial approach, the ANHS can be identified to reserve the neurohypophysis. Moreover, by understanding the anatomy of this membrane, the pituitary stalk was preserved in 3 patients (10.7%). CONCLUSIONS There is a significant membrane separating the anterior and posterior lobes of the pituitary gland, which lies behind the intermediate lobe. Understanding the anatomy of this septation is important for identifying and preserving the neurohypophysis and pituitary stalk during Id-CP surgery.

Normal dimensions of the posterior pituitary bright spot on magnetic resonance imaging.

OBJECT: The normal pituitary bright spot seen on unenhanced T1-weighted MRI is thought to result from the T1-shortening effect of the vasopressin stored in the posterior pituitary. Individual variations in its size may be difficult to differentiate from pathological conditions resulting in either absence of the pituitary bright spot or in T1-hyperintense lesions of the sella. The objective of this paper was to define a range of normal dimensions of the pituitary bright spot and to illustrate some of the most commonly encountered pathologies that result in absence or enlargement of the pituitary bright spot. METHODS: The authors selected normal pituitary MRI studies from 106 patients with no pituitary abnormality. The size of each pituitary bright spot was measured in the longest axis and in the dimension perpendicular to this axis to describe the typical dimensions. The authors also present cases of patients with pituitary abnormalities to highlight the differences and potential overlap between normal and pathological pituitary imaging. RESULTS: All of the studies evaluated were found to have pituitary bright spots, and the mean dimensions were 4.8 mm in the long axis and 2.4 mm in the short axis. The dimension of the pituitary bright spot in the long axis decreased with patient age. The distribution of dimensions of the pituitary bright spot was normal, indicating that 99.7% of patients should have a pituitary bright spot measuring between 1.2 and 8.5 mm in its long axis and between 0.4 and 4.4 mm in its short axis, an interval corresponding to 3 standard deviations below and above the mean. In cases where the dimension of the pituitary bright spot is outside this range, pathological conditions should be considered. CONCLUSIONS: The pituitary bright spot should always be demonstrated on T1-weighted MRI, and its dimensions should be within the identified normal range in most patients. Outside of this range, pathological conditions affecting the pituitary bright spot should be considered.

Endoscopic endonasal transsphenoidal "above and below" approach to the retroinfundibular area and interpeduncular cistern--cadaveric study and case illustrations.

OBJECTIVE: To evaluate the feasibility of reaching the interpeduncular cistern (IC) through an endoscopic endonasal approach that leaves the pituitary gland in place. METHODS: In a series of 10 injected cadaver heads, the transtuberculum ("above") and transclival ("below") approaches were combined, without pituitary transposition. Using 0-degree, 30-degree, and 45-degree endoscopes, the extent of overlap and if a blind spot occurred were determined. Also, the visualization of the IC was compared with the transposition of the pituitary gland approach. Nonparametric statistics were used to evaluate the results. The approach was implemented in 2 patients. RESULTS: For both the "above" and "below" views, there was a statistically significant increase in field of view when comparing the 0-degree endoscope with either the 30-degree endoscope (P < 0.05) or the 45-degree endoscope (P < 0.05). There was no difference between the 30-degree endoscope and the 45-degree endoscope (P > 0.05) in the "below" approach, but there was a difference (P < 0.05) in the "above" approach. There was no blind spot with any combination of endoscopes. There was no practical statistically significant difference between the transposition approach and the "above and below" approach. The "above and below" approach was used successfully in 2 surgeries. CONCLUSIONS: It is possible to work both "above" and "below" the pituitary gland to reach the IC through an endoscopic endonasal approach. The advantages are the maintenance of normal pituitary and parasellar anatomy and the minimization of the size of the skull base defect. There is no blind spot using this approach that would be revealed with a pituitary transposition. The feasibility of this approach has been confirmed in 2 patients.

A novel homozygous HESX1 mutation causes panhypopituitarism without midline defects and optic nerve anomalies.

OBJECTIVE: There are many genes reported to have been associated with combined pituitary hormone deficiencies, but mutations in HESX1 strongly correlate with septo-optic dysplasia. Our aim was to determine the cause of panhypopituitarism in our patient. PATIENTS AND METHODS: We studied an 8-month-old child having panhypopituitarism. The coding exons of PIT1, PROP1, LHX3, and HESX1 genes were amplified. Direct sequencing was done after denaturing HLPC. RESULTS: We identified a novel homozygous mutation (R160H) within the homeodomain of HESX1, which, to our knowledge, is the first to be described in humans. Neuroimaging studies revealed anterior pituitary aplasia, a normal posterior pituitary gland, and a thin pituitary stalk but no midline abnormalities. Optic nerve studies showed no pathology. This mutation is also carried in the parents of the affected child in a heterozygous pattern, suggesting an autosomal recessive inheritance. CONCLUSION: These data demonstrate that homozygous HESX1 mutation causing an R160H substitution can result in panhypopituitarism without midline defects.

Gestational diabetes insipidus: a review of an underdiagnosed condition.

OBJECTIVE: To review the etiology, diagnosis, and management of diabetes insipidus during pregnancy. DATA SOURCES: A search of the literature was performed in PubMed using key word searching and citation snowballing to identify articles published in English between January 1, 1980, and December 31, 2008, on the subject of diabetes insipidus during pregnancy. Once the articles were identified, a thorough review of all results was conducted. Results and conclusions were compiled and summarized. STUDY SELECTION: We reviewed 50 studies selected using the following key words: diabetes insipidus, pregnancy, arginine vasopressin, vasopressinase. CONCLUSION: Gestational diabetes insipidus is underdiagnosed because polyuria is often considered normal during pregnancy. Clinicians caring for pregnant women should consider screening for gestational diabetes insipidus, because it could be associated with serious underlying pathology.

Normal pituitary stalk: high-resolution MR imaging at 3T.

BACKGROUND AND PURPOSE: Knowing the normal imaging appearance of the pituitary stalk is important for the diagnosis of pituitary infundibular lesions, and more accurate assessment of the stalk may be possible at 3T than at 1.5T. Our purpose was to evaluate the normal pituitary stalk by use of high-resolution MR imaging at 3T. MATERIALS AND METHODS: Sagittal MPRAGE images and high-resolution oblique-axial T2-weighted images of the pituitary stalk were acquired in 29 healthy volunteers (16 men and 13 women; mean age, 28 years; age range, 21-43 years) at 3T. The diameter and length of the pituitary stalk and the depth of the infundibular recess were measured. Signal intensity of the stalk was visually evaluated on T2-weighted images. RESULTS: The AP and transverse diameters of the pituitary stalk were 2.32 +/- 0.39 mm and 2.16 +/- 0.37 mm at the pituitary insertion, respectively, and 3.25 +/- 0.43 mm and 3.35 +/- 0.44 mm at the level of the optic chiasm. No significant differences were observed between the AP and transverse diameters at each level. The length of the stalk was 5.91 +/- 1.24 mm, and the depth of the infundibular recess was 4.69 +/- 0.87 mm. The stalk showed central hyperintensity with a peripheral rim of isointensity in 20 subjects (69%) and homogeneous isointensity in 9 subjects (31%). CONCLUSIONS: The data of the current study can serve as standard measurements of the normal pituitary stalk. The central hyperintensity and peripheral rim may represent the infundibular stem and pars tuberalis, respectively.

Anatomía y espectro patológico de las lesiones del infundíbulo hipofisario / Anatomic and pathologic spectrum of pituitary infundibulum lesions

Objetivo. El espectro patológico de las enfermedades del infundíbulo hipofisario es variado. Revisamos 65 lesiones infundibulares en 44 adultos y 21 niños, y resumimos los hallazgos de imagen y su presentación clínica. Conclusión. Las enfermedades que afectan al infundíbulo hipofisario son muchas y distintas a las de la silla turca y la región paraselar. Las lesiones del tallo hipofisario pueden agruparse en tres categorías: congénitas y del desarrollo, infecciosas e inflamatorias, y neoplásicas. Conocer los hallazgos en imagen de las enfermedades específicas de los adultos y los niños es importante para hacer un diagnóstico correcto y aplicar el tratamiento adecuado (AU)

Objective. The pathologic spectrum of pituitary infundibulum disease is diverse. We reviewed 65 infundibular lesions in 44 adult and 21 pediatric patients, and summarized their imaging features and clinical presentation. Conclusion. The spectrum of pathology involving the pituitary infundibulum is broad yet distinct from other pathology in the sella and parasellar region. Pituitary stalk lesions can be grouped into three categories: congenital and developmental, inflammatory and infectious, and neoplastic. Knowledge of the imaging appearance of diseases specific to adults and to children is important for accurate diagnosis and treatment (AU)

[MRI imaging of the neural pituitary]. / Imagerie par résonance magnétique nucléaire de la neurohypohyse.

The main illness of the neural pituitary is diabetes insipidus (DI). MRI is essential if DI occurs during childhood, in order to highlight malignant germinoma prognosis of which remains excellent if the diagnosis is made as early as possible. In adults, primary intracranial tumours causing DI include craniopharyngioma, or pineal tumours. Infiltrative histiocytosis is another frequent aetiology. One third of previously considered idiopathic DI is in fact auto-immune. Early MRI findings advocate for such a diagnosis. Finally, meticulous analysis of the neural pituitary imaging may avoid several pitfalls and help the analysis of adenopituitary abnormalities.

Clinical importance of the basal cavernous sinuses and cavernous carotid arteries relative to the pituitary gland and macroadenomas: quantitative analysis of the complete anatomy.

BACKGROUND: It is unusual to encounter hemorrhagic complications caused by arterial or venous damage during TSS. Problems with these structures can lead to permanent disability or death. Our aim was to quantitatively analyze anatomical and radiologic relationships among the BCS, the CCA, and the pituitary gland, as these structures are accessed during TSS. METHODS: Forty-nine formaldehyde-fixed, sellar-parasellar tissue blocks from adult cadavers were used to simulate accessing the BCSs via TSS. In each specimen, size of the pituitary gland and specific characteristics of each BCS and the horizontal segment of each CCA were recorded. Nine other specimens were used for histologic investigation and microanatomical measurements. To attest correlation between clinical data and cadaveric measurements, coronal MRI scans of 22 healthy adults as well as of 28 patients with macroadenomas were analyzed. RESULTS: In cadaveric specimens, distances between both CCAs in the BCS were 17.1 +/- 4.0 mm anteriorly, 20.3 +/- 4.2 mm medially, and 18.8 +/- 4.6 mm posteriorly. In this study, the anterior medial space of the BCS was dominant in 12 specimens on the right side and in 5 specimens on the left; the posterior medial space of the BCS was dominant in 23 specimens on the right side and in 9 specimens on the left side. The right medial BCS was dominant in 35 specimens. On histologic coronal sections, some part of the carotid artery's (CA's) diameter was located below the line passing from the basal dural layer ranging from 5.3% to 65.4%. In normal-sella images, distances between both CCAs were 15.4 +/- 1.8 mm anteriorly, 16.0 +/- 2.8 mm medially, 16.2 +/- 3.4 mm posteriorly. On coronal normal-sella images, some part of the CA's diameter was located below the line passing from the basal dural layer ranging from 16.4% to 66.7%. In macroadenomas, distances between both CCAs were 22.0 +/- 3.6 mm anteriorly, 21.5 +/- 3.8 mm medially, and 20.7.2 +/- 3.7 mm posteriorly . On coronal images, in only 6 of 28 macroadenomas, some part of the CA's diameter was located below the line passing from the basal dural layer ranging from 12.5% to 100%. CONCLUSIONS: Our results indicate that a working area of 15.0 +/- 2.6 x 10.3 +/- 2.1 mm is safe during TSS. The position of the CCA posterior segment was notably more caudal than the anterior segment with respect to the basal dura, which should be taken into account during extended exposure. Also, preoperative recognition of the anatomical variations is beneficial for detection of the boundaries of dissection, which is particularly important in the BCS, where variable course of CCAs may transform the anatomical configuration. Slowly growing pituitary adenomas stretch out both CCAs considerably from medial to lateral directions, and they cause widening of intercarotid distances in all segments. Processing of fixation, decalcification, and paraffin embedding for the cadaveric tissue in contrast to physiologically hydrated tissues may change the accuracy of measurements. These measurements are significantly different than those in the radiologic images when arterial blood under pressure is in the CCA as well as when venous blood fills the cavernous sinus as is the case in vivo. In clinical practice, these facts must be taken into consideration in the cadaveric measurements.

The circumventricular organs: an atlas of comparative anatomy and vascularization.

The circumventricular organs are small sized structures lining the cavity of the third ventricle (neurohypophysis, vascular organ of the lamina terminalis, subfornical organ, pineal gland and subcommissural organ) and of the fourth ventricle (area postrema). Their particular location in relation to the ventricular cavities is to be noted: the subfornical organ, the subcommissural organ and the area postrema are situated at the confluence between ventricles while the neurohypophysis, the vascular organ of the lamina terminalis and the pineal gland line ventricular recesses. The main object of this work is to study the specific characteristics of the vascular architecture of these organs: their capillaries have a wall devoid of blood-brain barrier, as opposed to central capillaries. This particular arrangement allows direct exchange between the blood and the nervous tissue of these organs. This work is based on a unique set of histological preparations from 12 species of mammals and 5 species of birds, and is taking the form of an atlas.

Novel HESX1 mutations associated with a life-threatening neonatal phenotype, pituitary aplasia, but normally located posterior pituitary and no optic nerve abnormalities.

CONTEXT: Hesx1 is one of the earliest homeodomain transcription factors expressed during pituitary development. Very few HESX1 mutations have been identified in humans; although in those cases the disease phenotype shows considerable variability, all but one of the patients display an ectopic posterior pituitary and/or optic nerve abnormalities. OBJECTIVE: The objectives of the study were to describe the complex phenotype associated with the panhypopituitarism of two unrelated Italian patients who, at birth, presented with hypoglycemic seizures and respiratory distress complicated by shock, in a familial context of neonatal death in one family and spontaneous miscarriage in both families and to identify the molecular basis of this unusual syndrome. MAIN OUTCOME MEASURES: Magnetic resonance imaging of the pituitary region, study of HESX1 gene and transcripts, and assessment of the ability of mutated HESX1 proteins to repress transcription were measured. RESULTS: Magnetic resonance imaging examination showed an anterior pituitary aplasia in a flat sella turcica and a normally located posterior pituitary in both patients. A constellation of extrapituitary developmental defects were found in the two patients, but without any optic nerve abnormalities. Sequencing of HESX1 exons and their flanking intronic regions revealed two different homozygous mutations. A frameshift (c.449_450delAC) was identified in one case, whereas the other patient carried a splice defect (c.357 + 2Tb > C) confirmed by the study of HESX1 transcripts. If translated, these mutations would lead to the synthesis of truncated proteins partly or entirely lacking the homeodomain, with no transcriptional repression, as shown by their inability to inhibit PROP1 activity. CONCLUSIONS: These observations reveal two novel HESX1 mutations in a so-far-undescribed disease phenotype characterized by a life-threatening neonatal condition associated with anterior pituitary aplasia, in the absence of ectopic posterior pituitary and optic nerve abnormalities, two features classically associated with HESX1 defects.

Immunohistochemical study of somatotrophs in pituitary pars distalis of male viscacha (Lagostomus maximus maximus) in relation to the gonadal activity.

Somatotrophs were identified and quantified in pituitary pars distalis of male viscachas (Lagostomus maximus maximus) during the annual reproductive cycle, after the administration of melatonin, after castration and in different growth stages by immunohistochemistry and morphometric analysis. In adult male viscachas, the somatotrophs were distributed throughout the pars distalis during the reproductive cycle. They were oval, pyramidal or round in shape with a large round nucleus. The percentage immunopositive area, the major cellular diameter and the number of cells decreased during the gonadal regression period in relation to the values found in the reproductive period. The administration of melatonin did not provoke any variations of the morphometric parameters studied. On the contrary, a significant decrease in the percentage immunopositive area, in the major cellular diameter and in the number of somatotrophs in castrated viscachas was observed. The study of different growth stages showed that these morphometric parameters increased from immature to adult animals in the reproductive period. The results obtained suggested that the variations of the morphometric parameters of somatotrophs are more related to the gonadal development and activity than to a direct effect of melatonin.

Co-expression of vasopressin and androgen-binding protein in the rat hypothalamus.

In previous studies we have observed the expression of androgen binding protein (ABP) in the rat hypothalamo-neurohypophysial system. With immunocytochemical double staining we found partial co-localization with oxytocin. In the present study we used antibodies to the anti-diuretic hormone arginine vasopressin (AVP) for co-localization with ABP in the rat hypothalamus. Both antigens were seen in the magnocellular paraventricular and supraoptic nuclei. Dense fiber networks with varicosities containing both AVP and ABP immunoreactivity were visible throughout the hypothalamus, the median eminence and in the posterior pituitary lobe. Double immunostaining revealed also co-existence in the parvocellular portion of the paraventricular nucleus and in the suprachiasmatic nucleus. ABP immunoreactive neurons in the preoptic region were devoid of AVP staining, AVP neurons in the bed nucleus of the stria terminalis stained only occasionally for ABP. We conclude that both the magnocellular and the parvocellular hypothalamic vasopressin systems are capable of expressing the steroid binding globulin, which is probably subject to axonal transport, along with the peptide hormone. Intrahypothalamic expression of ABP may be among the mechanisms necessary for rapid actions of steroids on hypothalamic neuroendocrine systems.

Connection between the arcuate nucleus and the posterior lobe of the hypophysis. An angiotensin II immunohistochemical study in rats

The aim of this study was to perform an immunohistochemical study of the, angiotensinergic pathway from the arcuate nucleus (AN) to the posterior lobe of the hypophysis (PLH) of 10-week-old matched normotensive Wistar Kyoto rats (WKY), using our own policlonal antibody raised in mice against Angiotensin II (mouseantiangiotensin II, MAAII). Cells and fibers in the rostroventral and dorsocaudal parts of the AN, the internal zone of the median eminence and PLH showed immunoreactive material for antiangiotensin II. Angiontensin II fibers originating in the anteroventral part of the AN, crossing median eminence (ME) and infundibular stem and arriving at the PLH were also observed (AU)

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Three-dimensional architecture and distribution of collagen components in the goat hypophysis.

The three-dimensional architecture of collagen fibrils in the connective tissue framework and the distribution of collagen types in the goat hypophysis were studied by the cell maceration method in combination with scanning electron microscopy (SEM) and immunohistochemistry. The pars distalis of the adenohypophysis consisted of many cell clusters. SEM revealed that the wall of cell clusters appeared as various-sized flat bundles of collagen fibrils woven in a basket-like configuration. In the pars tuberalis, the aggregates of collagen fibrils were denser and bundles thicker compared to the pars distalis. The density of collagen fibrils changed from the pars tuberalis to pars distalis without a distinct border. The collagen framework in the pars intermedia was mainly divided into three parts, the dorsal region with large hollows, the middle region, and the ventral sheet facing the cavum hypophysis. In the lobus nervosus of the neurohypophysis, the collagen network exhibited a sponge-like appearance at low magnification. Collagen fibrils of various sizes consisted of loose wavy bundles distributed around the cavities. Immunohistochemistry revealed types I, III, IV, V, and VI collagen throughout the hypophysis. It is concluded that to maintain structural and functional integration, the components of collagen are in different configurations throughout the regions of the goat hypophysis.

Oestrogen receptor-beta and neurohypophysial hormones: functional interaction and neuroanatomical localisation.

Oestrogens affect fluid balance, influencing both ingestive behaviour and renal excretion. The renal effects are partly due to altered release of vasopressin and oxytocin. This study was designed to explore the role of oestrogen receptor-beta (ERbeta) in neurohypophysial hormonal function. Following dietary administration, soya isoflavones reach the brain in sufficient concentration to activate ERbeta, but not oestrogen receptor-alpha (ERalpha). ERbeta function was therefore manipulated by feeding rat diets differing in soya isoflavone content. Fluid balance and neurohypophysial hormone release were measured in male rats maintained for 14 days on a soya isoflavone-free diet or one containing 150 microg/g genistein+daidzein. Food and water intake, body weight, urine flow, osmolality and sodium concentrations were determined daily. After 14 days, plasma and urine osmolality and sodium, vasopressin and oxytocin concentrations were determined. There was no significant difference in weight gain between the two groups or in their excretion of sodium and water or plasma sodium and plasma oxytocin. However, plasma vasopressin was significantly lower in the iso-free group. Double-label immunocytochemistry was used to assess colocalisation of ERbeta with the neurohypophysial hormones in male rats. Cell nuclei showing ERbeta immunoreactivity were abundant in the posterior magnocellular paraventricular nucleus (PVNpm) and in the supraoptic nucleus (SON). Vasopressin-immunoreactive neurones were similarly distributed, forming the core of the PVNpm and the ventral portion of the SON; majority were positive for ERbeta. Cells with oxytocin immunoreactivity were located mainly at the periphery of the PVNpm and in the dorsal SON; only approximately a quarter of these cells showed ERbeta immunoreactivity. Thus, the difference in the effects of the soya diet on vasopressin and oxytocin release may be related to the ERbeta-activating properties of this diet and to the preponderance of this receptor in vasopressin as opposed to oxytocin cells.