The tuber cinereum as a circumventricular organ: an anatomical study using magnetic resonance imaging.

PURPOSE: The tuber cinereum (TC) comprises the hypothalamic gray matter that forms the anterior portion of the third ventricle floor. However, since it has been rarely documented in previous neuroimaging investigations, the aim of the current study was to explore the morphology of the TC using magnetic resonance imaging (MRI). METHODS: Ninety-two patients were enrolled in this study. Following initial examination with conventional MRI sequences, a contrast study using intravenous gadolinium injection was performed in thin-sliced sections. RESULTS: The TC, which was commonly defined as a linear, enhancing structure on the midsagittal section, was identified in all 92 cases. In 83% of cases, the third ventricle floor had a gentle inflection at the junctional site between the median eminence and TC. The angle formed between the line parallel to the TC and the horizontal line showed considerable variability, which ranged from 0.5° to 56°. Furthermore, a non-enhancing segment of variable length was identified in the posterior-most TC. In 11% of cases, the midline TC was enhanced over the whole length. CONCLUSIONS: Since the most part of the midline TC was enhanced with intravenous gadolinium injection, it may function as a circumventricular organ. The TC should be evaluated with contrast sagittal MRI prior to performing surgery with management of the anterior third ventricle floor.

Premio Sixto Obrador 2013. Modelo topográfico de 3 ejes para el tratamiento quirúrgico de los craneofaringiomas. Parte II: Evidencias anatómicas y neurorradiológicas que definen el modelo de clasificación de 3 ejes y su utilidad para predecir el riesgo quirúrgico individual / The 2013 Sixto Obrador Award. A triple-axis topographical model for surgical planning of craniopharyngiomas. Part II: Anatomical and neuroradiological evidence to define triple-axis topography and its usefulness in predicting individual surgical risk

INTRODUCCIÓN Y OBJETIVOS: Este estudio analiza las evidencias patológicas y de imagen de resonancia magnética que definen la topografía de los craneofaringiomas y permiten una clasificación de las lesiones según el riesgo de daño hipotalámico que estas asocian. MATERIAL Y MÉTODOS: Se ha realizado un análisis sistemático de los métodos de clasificación topográfica empleados en las series quirúrgicas de craneofaringiomas descritas en la literatura (n = 145 series, 4.588 craneofaringiomas). También se analizaron las relaciones topográficas de casos individuales intervenidos y bien descritos de la literatura (n = 224 casos) y de casos estudiados en autopsias (n = 201 casos). Finalmente, se analizaron y compararon los estudios prequirúrgicos y posquirúrgicos de imagen de resonancia magnética de craneofaringiomas bien descritos (n = 130) para establecer un modelo diagnóstico topográfico en 3 ejes de la lesión, que permite anticipar cualitativamente el riesgo quirúrgico asociado de daño hipotalámico. RESULTADOS: Las 2 principales variables pronósticas que definen la topografía del craneofaringioma son su posición con respecto al diafragma selar y la afectación del suelo del tercer ventrículo. Un modelo diagnóstico de 5 variables, que son: edad del paciente, existencia de hidrocefalia o de alteraciones del comportamiento, posición relativa de los hipotálamos y el valor del ángulo mamilar, permiten diferenciar craneofaringiomas supraselares que comprimen el tercer ventrículo (craneofaringiomas seudointraventriculares) de lesiones estrictamente intraventriculares o aquellas con un crecimiento primario en el suelo del tercer ventrículo (craneofaringiomas infundibulotuberales o no estrictamente intraventriculares). CONCLUSIONES: Un modelo de clasificación topográfica de los craneofaringiomas en 3 ejes que incluya el grado de infiltración del hipotálamo es útil para la planificación del abordaje y el grado de resección. Los craneofaringiomas infundibulotuberales representan un 42% de los casos y muestran una adherencia fuerte y circunferencial al suelo del tercer ventrículo, asociando un riesgo de daño hipotalámico del 50%. El abordaje transesfenoidal endoscópico permite valorar la adherencia tumoral hipotalámica bajo visión directa

INTRODUCTION AND OBJECTIVES: This study evaluates the pathological and magnetic resonance imaging evidence to define the precise topographical relationships of craniopharyngiomas and to classify these lesions according to the risks of hypothalamic injury associated with their removal. MATERIAL AND METHODS: An extensive, systematic analysis of the topographical classification models used in the surgical series of craniopharyngiomas reported in the literature(n = 145 series, 4,588 craniopharyngiomas) was performed. Topographical relationships of well-described operated craniopharyngiomas (n = 224 cases) and of non-operated cases reported in autopsies (n = 201 cases) were also analysed. Finally, preoperative and postoperative magnetic resonance imaging studies displayed in craniopharyngiomas reports (n = 130) were compared to develop a triple-axis model for the topographical classification of the selesions with qualitative information regarding the associated risk of hypothalamic injury. RESULTS: The 2 major variables with prognostic value to define the topography of a craniopharyngioma are its position relative to the sellar diaphragm and its degree of invasion of the third ventricle floor. A multivariate diagnostic model including 5 variables -patient age, presence of hydrocephalus and/or psychiatric symptoms, the relative position of the hypothalamus and the mammillary body angle- makes it possible to differentiate suprasellar craniopharyngiomas displacing the third ventricle upwards (pseudointraventricular craniopharyngiomas) from either strictly intraventricular craniopharyngiomas or lesions developing primarily within the third ventricle floor (infundibulo-tuberal or not strictly intraventricular craniopharyngiomas). CONCLUSIONS: A triple-axis topographical model for craniopharyngiomas that includes the degree of hypothalamus invasion is useful in planning the surgical approach and degree of resection. Infundibulo-tuberal craniopharyngiomas represent 42% of all cases. These lesions typically show tight, circumferential adhesion to the third ventricle floor, with their removal being associated with a 50% risk of hypothalamic injury. The endoscopically-assisted extended transsphenoidal approach provides a proper view to assess the degree and extension of craniopharyngioma adherence to the hypothalamus

Colocalization of a carnosine-splitting enzyme, tissue carnosinase (CN2)/cytosolic non-specific dipeptidase 2 (CNDP2), with histidine decarboxylase in the tuberomammillary nucleus of the hypothalamus.

Carnosine is a naturally occurring dipeptide (beta-alanyl-l-histidine) present in mammalian tissues such as the brain and skeletal muscles. Carnosine is not only a radical scavenger but also a possible neurotransmitter-like molecule that regulates neuronal functions such as hypothalamic control of the autonomic nervous system. CN2 (CNDP2) is a cytosolic enzyme that can hydrolyze carnosine to yield l-histidine and beta-alanine. In order to understand the functions of carnosine and CN2 in the brain, we have investigated the immunohistochemical localization of CN2 in the hypothalamus. CN2-immunoreactivity was highly concentrated in neuronal cells in the dorsal part of the tuberomammillary nucleus of the posterior hypothalamus. Since the tuberomammillary nucleus is the exclusive origin of histaminergic neurons, we further investigated whether CN2 is present in the histaminergic neurons. We found that CN2-immunoreactivity was colocalized with that of histidine decarboxylase, which is the key enzyme for histamine biosynthesis specifically expressed in the histaminergic neurons of the tuberomammillary nucleus. These results suggest that CN2 is highly expressed in the histaminergic neurons in the tuberomammillary nucleus, implying that it may supply histidine to histaminergic neurons for histamine synthesis.

Neuroendocrine regulation of thyrotropin-releasing hormone (TRH) in the tuberoinfundibular system.

[...] It is now required to list each part needed for mucous excretion. They are two ducts in the brain substance, then a thin portion of membrane shaped as the infundibulum, then the gland that receives the tip of this infundibulum and the ducts that drive the mucus (pituita) from this gland to the palate and nares. [...] and I said that one (duct) [...] from the middle of the common cavity (third ventricle) descends [...] into the brain substance, and the end of this duct is [...] the sinus of the gland where the brain mucus is collected [...].

The preoptico-infundibular LH-RH tract of the rat.

Following partial or total deafferentation of the right side of the medial basal hypothalamus (MBH) of female rats, distribution of luteinizing hormone-releasing hormone (LH-RH) axons in and around the isolated area was studied. Accumulation of the hormone along the cut indicated the directions from which LH-RH axons arrived to the isolated hypothalamic area. A comparison of the intact side of the median eminence (ME) to the deafferented side indicated the areas where the transected LH-RH axons would have ended. It was concluded that: (i) LH-RH axons of the MBH of the rat originate from extrahypothalamic areas and approach the ME through the preoptico-infundibular LH-RH tract; (ii) axons from the lateral fascicles of this tract turn toward the ME under oblique angle, consequently, a paramedian sagittal cut causes primary degeneration of the LH-RH terminals only behind the rostral level of the cut, and diminution of these terminals will last even behind the caudal end of the cut; (iii) the tubero-infundibular tract of the rat does not contain LH-RH axons; and (iv) a certain percentage of the LH-RH axons in the ME originates from the contralateral side of the brain.

Nucleus praeopticus and nucleus lateralis tuberis of Salmo salar and Salmo gairdneri: structure and relationship to the hypophysis.

The nucleus praeopticus (NPO) is located on both sides of the preoptic recess and is composed of a pars parvocellularis and a pars magnocellularis. Only in the rainbow trout does the pars magnocellularis consist of separately located medium-sized cells and very large cells. Cytologically, three cell types can be distinguished: 1) unipolar cells ending in the cerebrospinal fluid (CSF), 2) bipolar cells also ending in the CSF and forming an axon, and 3) multipolar cells which generally do not have a direct connection with the ventricle. Axons originate from the cell bodies forming the paired preopticohypophysial tract that runs along the border of the diencephalon and the optic tract. A considerable number of NPO fibers leading to the hypophysis makes close contact with the cell bodies of the pars lateralis of the nucleus lateralis tuberis, indicating a functional relationship. Most NPO fibers terminate in the caudal part of the neurohypophysis, around blood capillaries and at the basal lamina of the pars intermedia. Far fewer fibers appear to terminate near the boundary of the neurohypophysis and the rostral and proximal pars distalis. The nucleus lateralis tuberis (NLT) is located in the caudal hypothalamus, beginning at the rostral end of the horizontal commissure and extending caudally beyond the hypophysial stalk. It consists of the partes rostralis, medialis, lateralis and ventrolateralis. In both species the p. rostralis contains small subependymal neurons and some larger ones. Only in the p. medialis of the Atlantic salmon are large cells present. In both species the most prominent part is the p. lateralis, which consists solely of large cells. Cells situated between the p. medialis and the p. lateralis are grouped in the p. ventrolateralis. It was impossible to trace the axons originating in the NLT, since the cyto- and axoplasm could not be stained specifically. The structure of the NPO and NLT in the two salmonid species is compared with that of other teleosts.

The fine structure of the ependymal surface of the recessus infundibularis in the rat.

The surface of the recessus infundibularis of the third ventricle has been studied with the scanning and transmission technique in normal and experimental material. Surface specializations such as microvilli, craters and areas of discontinuous lining are described. Supraependymal cells and fibres have been found; some of these cells form wide-meshed networks. The supraependymal fibres may be regular or varicose; the former seem to perforate the ependyma. With the transmission electron microscope the supraependymal cells are divided into three categories; nerve cells, lymphocytes and "dense cells". Two fibre populations are distinguished: thin profiles (nerve fibres) and thick profiles (nerve terminals). Axosomatic and axoaxonic synapses are described. Synapses between supraependymal fibres and ependyma cells have also been found.

A cytoarchitectonic atlas of the mouse hypothalamus.

A description of the organization, areas, and cell groups within the hypothalamus of the mouse is presented in detail. Photomicrographs of cell-stained serial sections through the hypothalamus in frontal, sagittal and horizontal planes are included. The hypothalamus has been divided basically into medial and lateral parts with most well-defined cell groups or nuclei lying within the medial subdivision and surrounded by diffuse collections of cells referred to as areas. The heterogenetiy of cell types within most hypothalamic nuclei and areas has been emphasized with the consequent implications for heterogeneity of neuronal connections and of functions. Recently introduced neuroanatomical techniques permitting increased attention to the cellular level of organization have demonstrated precise connections and functional localization of cells within the hypothalamus. While cytoarchitectonic distinctions imply functional distinctions, morphological and experimental evidence suggest the existence also of systems of cells which transcend conventional cytoarchitectonic boundaries, the cells within each system being interconnected functionally or neuronally.

[Nucleus tuberis lateralis in the human brain. A pigmentarchitectonic study]. / Uber den Nucleus tuberis lateralis im Gehirn des Menschen. Eine pigmentarchitektonische Studie

In the present article the shape of the nucleus tuberis lateralis and a hitherto unknown cell group in the human hypothalamus is described. Neurolipofuscin is selectively stained with aldehyde-fuchsin. This method enables the exact determination of the three dimensional shape of a griseum by using slices more than 500 mum thick. Differences in the distribution and amount of pigment within different types of nerve cells provide a basis for cellular demarcation and subdivision (pigmentarchitectonics). The intensely stained nucleus tuberis lateralis can be seen as consisting of a main lateral and a medial group. There are elevan cell groups which constantly occur. The individual range of their shapes causes a great variation in the shape of the lateral tuberal nucleus. It also has portions in the medial field of the hypothalamus: a pars suprafornicalis and 'mediale Streuzellen' ('medial scatter-cells'). Rostrally it extends almost to the chiasma with scattered irregularly occurring groups of cells. The amount of intracellular lipofuscin depends on the respective cell group and the age of the brain. By the age of 12 years the nucleus is already more intensely pigmented than the surrounding grisea. There is an indication of a tendency towards an aggregation of the cell groups with age. Connections between pigmentation and the phylogeny are discussed. Ventrally the nucleus tuberis lateralis is bounded by a hitherto undescribed heteromorphous cell group. It is clearly delimited and can be divided into a longish pars lateralis and a spherical pars medialis. Both parts consist of small as well as medium-sized cells which accumulate diffusely distributed granula of lipofuscin in adult brains. The name 'nucleus paratuberalis' is suggested for this griseum.

Medial hypothalamic nuclei in the macaque (Macaca mulatta) brain.

The term 'medial hypothalamus' is used here for the region situated between the anterior hypothalamus and mamillary body (without the lateral hypothalamic area). The paper is based on a series from the macaque brain in three principal planes and stained by the Weigert-Wolters, Klüver-Barrera, Nissl, and Schultze methods. The following parts have been differentiated in the medial hypothalamus: the ventromedial, dorsomedial, dorsal, dorsocaudal, and infundibular nuclei.