A morphometric comparative study of the medial geniculate body of the rabbit and the fox.

SUMMARY: Unbiased stereological methods were used to morphometrically examine and compare the medial geniculate body (MGB) of two species from different mammalian orders. The MGB had a similar nuclear pattern, and it was parcelled into three major cytoarchitectural areas: the dorsal nucleus (MGd), the ventral nucleus (MGv) and the medial nucleus (MGm). The MGd was predominant in the fox, where it contributed nearly 50% to the total MGB volume, while in the rabbit, the MGv was insignificantly larger than the MGd. In both species, the percentage contribution of the MGm was the lowest. The MGd in the fox was also characterized by twice as many neurons per mm(3) as in the rabbit, whereas a reverse proportion was observed in the MGm, although the numerical density in the MGv was very similar in both species. The total number of MGB neurons in the fox was over twice higher than that in the rabbit. The variability in the percentage contribution of the MGd, MGv and MGm cells to the total neuronal population of the MGB was different in both mammals. In the rabbit, there was a larger contribution from the MGv and MGm, while in the fox, the MGd was predominant. These data demonstrate that the main areas of the MGB complex differ in terms of the morphometric characteristics in both species. Our results also show that the negative correlation between the volume and numerical density in the sensory centres of the brain might not be as distinct as in the non-sensory brain structures.

A morphometric study of the preoptic area of the guinea pig.

The aim of the study was to provide the topography and morphometric characteristics of the preoptic area (POA) of the guinea pig. The study was carried out on the brains of sexually mature guinea pigs of both sexes. A uniform procedure was followed in the study of the paraffin-embedded brain tissue blocks of males and females. The blocks were cut in the coronal plane into 50 mm sections and stained according to the Nissl method. The guinea pig POA consists of four parts: the medial preoptic area (MPA), lateral preoptic area (LPA), periventricular preoptic nucleus (PPN), and median preoptic nucleus (MPN). The topography and general structure of POA parts are similar in males and females. However, the PPNa cells of females are more intensely stained and are more densely packed than the PPNa cells of males. For morphometric analysis, the MPA and LPA as well as PPN and MPN were considered respectively as uniform structures, namely MPA-LPA and PPN-MPN. The statistical analysis showed that the volume of the PPN-MPN was larger in males than in females, whereas the MPA-LPA volume did not differ between the sexes. Moreover, the numerical density and the total number of neurons were statistically larger in males than in females in both the MPA-LPA and PPN-MPN. The parameters describing POA neurons were larger for MPA-LPA neurons in comparison with the PPN-MPN neurons. However, in this respect no sex differences were observed in both studied complexes.

A morphometric comparative study of the lateral geniculate body in selected placental mammals: the common shrew, the bank vole, the rabbit, and the fox.

The lateral geniculate body (LGN) was morphometrically examined and compared in representatives of four mammalian orders (Insectivora, Rodentia, Lagomorpha, and Carnivora). In each studied species, the lateral geniculate body was divided into two distinct parts: the dorsal nucleus (LGNd) and the ventral nucleus (LGNv). The lateral geniculate body of the common shrew and the bank vole are very similar in appearance and nuclear pattern. The dorsal and ventral nuclei of these two species also have the most similar statistical characteristics. The lateral geniculate body of the fox has the most complicated morphology and multilayered structure. A significant disproportion was observed between the sizes of both geniculate nuclei in the fox, where the dorsal nucleus definitely surpassed the ventral nucleus in terms of volume. With the exception of the fox, the neuronal density of the LGN nuclei was negatively correlated with the volumes of the LGN. The mean neuronal size of the LGNd and LGNv, which was the resultant of the length, width, area, and circumference of the soma, grew correlatively to the volumes of these nuclei. In all examined species, somas of the LGNd neurons are distinctly larger and have more similar shapes than the LGNv perikarya. In addition, the numerical density of neurons in the ventral nucleus is significantly higher than in the dorsal nucleus. All these morphometric parameters clearly differentiate the LGNd from the LGNv.

The morphometric study of the amygdala in the rabbit.

Volumetric measurements of the individual nuclei in the amygdala (CA) of the rabbit reveal poor development of the basolateral (BL) and lateral olfactory tract (NLOT) and medial (ME) nuclei. On the other hand, the volumes of the lateral (LA), basomedial (BM), central (CE) and cortical (CO) nuclei are remarkable in this species. A comparison of the densities of neurons in the individual nuclei with the mean numerical density of cells in the rabbit CA indicates that the densities of neurons in LA, BL and BM are significantly lower than the mean (p < 0.05), whereas in CE, CO, ME and NLOT these values are significantly higher than the mean (p < 0.05). It should be noted, however, that of all the nuclei studied those in CE show the greatest similarity in density to CA as a whole. To some extent a similar division of the rabbit CA may be made using the size parameters of the amygdaloid neurons as a marker. The large neurons populate less densely organised CA areas such as LA, BL and BM, whereas the small cells create ME and NLOT, where the neurons are densely arranged. The CE and CO occupy intermediate positions, with the neurons similar in size to the mean for the total rabbit CA. These morphometric data from CA in the rabbit, when compared with the similar data for the common shrew and guinea pig (see our previous papers), lead to the conclusion that the amygdalae in all three species are very similar with respect to the distribution of neurons in relation to density and size and that, when volumetric measurements are taken into account, CA in the rabbit is much more similar to that of the guinea pig than that of the common shrew.

The nerve cells of the neostriatum in the common shrew (Sorex araneus) and bank vole (Clethrionomys glareolus): a Golgi comparative study.

The studies were carried out on 12 brains derived from adult representatives of two mammalian orders, Insectivora and Rodentia. The neostriatum was compared in the common shrew (Sorex araneus) and bank vole (Clethrionomys glareolus). Three main types of striatal neuron were distinguished in the common shrew and five types of neurons in the bank vole. The fifth type of bank vole neurons was additionally divided into two subtypes with respect to dendritic pattern.

The neuronal structure of the dorsal nucleus of the lateral geniculate body in the common shrew (Sorex araneus) and the bank vole (Clethrionomys glareolus): Golgi and Nissl studies.

The topography and neuronal structure of the dorsal nucleus of the lateral geniculate body (GLd) of the common shrew and the bank vole are similar. The lateral geniculate body of both the species examined has a homogeneous structure and no observable cytoarchitectonic lamination. On the basis of the shape of the dendritic arbours as well as the pattern of dendritic arborisations the following two types of neurons were distinguished. Type I "bushy" neurons that have multipolar or round perikarya (common shrew perikarya 9-12 microm, bank vole perikarya 10-13 microm), with 4-6 short thick dendritic trunks that subdivide into many bush-like branches. The dendritic trunks are smooth, in contrast to the distal branches, which are covered with numerous spine-like protrusions of different lengths and forms. An axon emerges from the soma, sometimes very close to one of the primary dendrites. The type I neurons are typically projection cells that send their axons to the primary visual cortex. These neurons predominate in the GLd of both species. Type II neurons, which have an elongated soma with primary dendrites arising from opposite poles of the perikaryon (common shrew perikarya 8-10 microm, bank vole perikarya 9-11 microm). The dendritic arbours of these cells are less extensive and their dendrites have fewer spines than those of the type I neurons. Axons were seldom observed. The type II neurons are presumably interneurons and are definitely less numerous than the type I neurons.

The neuronal structure of the preoptic area in the mole and the rabbit: Golgi and Nissl studies.

The present studies were carried out on the brains of the adult mole and rabbit. The preparations were made by means of the Golgi technique and the Nissl method. Two types of neurons were distinguished in the preoptic area (POA) of both species: bipolar and multipolar. The bipolar neurons have oval, fusiform or round perikarya and two dendritic trunks arising from the opposite poles of the cell body. The dendrites bifurcate once or twice. The dendritic branches have swellings, single spine-like and filiform processes. The multipolar neurons usually have triangular and quadrangular perikarya and from 3 to 5 dendritic trunks. The dendrites of the mole neurons branch sparsely, whereas the dendrites of the rabbit neurons display 2 or 3 divisions. On the dendritic branches varicosities and different protuberances were observed. The general morphology of the bipolar and multipolar neurons is similar in the mammals studied, although the neurons of the rabbit POA display a more complicated structure. Their dendritic branches show more divisions and possess more swellings and different processes than the dendrites of the neurons of the mole POA. Furthermore, of the multipolar neurons only the dendrites in POA of the rabbit were observed to have a rosary-like beaded appearance.

The neuronal structure of the dorsal lateral geniculate nucleus in the guinea pig: Golgi and Klüver-Barrera studies.

On the basis of Golgi and Klüver-Barrera preparations we have distinguished four types of neurons in the dorsal lateral geniculate nucleus of the guinea pig: 1. Fusiform neurons with 1-3 thick dendritic trunks arising from each pole of the soma. The dendritic trunks branch twice dichotomically. The branches sometimes show varicosities. 2. Pear-shaped cells. From one pole of the perikaryon one or two thick dendritic trunks arise, from the opposite pole an axon emerges. The ends of the dendritic branches divide in a tuft-like manner (a characteristic feature of the interneurons). 3. Rounded neurons with 4-7 dendritic trunks without cones. The dendritic trunks branch once or twice dichotomically and give finally 2-3 thin ramifications which show a varicose course and knob-like protuberances. 4. Triangular cells with 3 thick, chronically arising dendritic trunks. They bifurcate dichotomically. The surface of the dendritic trunks and of their branches is smooth.

The neuronal structure of the ventromedial and infundibular nuclei in the guinea pig: Nissl and Golgi study.

The studies were carried out on the mesencephalons of adult guinea pigs. On the basis of the Golgi technique, as well as the Nissl and Klüver-Barrera methods, four types of neurons were distinguished in the ventromedial nucleus (VMH) and infundibular nucleus (Ni): 1. Rounded neurons (perikarya 12-18 microns) with 3-4 dendritic trunks, which divide once, twice or not at all. The dendritic branches possess varicosities and knob-like spines. These neurons predominate in VMH. 2. Fusiform neurons (perikarya 15-28 microns) with 2 dendritic trunks, which arise from the opposite poles of the cell body. Bead-like protuberances and knob-like processes are observed on the dendrites. These neurons are the most numerous in Ni. 3. Triangular neurons (perikarya 15-22 microns) possess three thick, conical dendrites, which bifurcate dichotomically. Bead-like appendages and knob-like processes were seen on the dendritic surface. 4. Multipolar neurons (perikarya 18-22 microns) with 4-5 dendritic trunks, which are poorly ramified. The dendritic branches are smooth, but varicosities can be observed on their surface. In all types of neurons an axon was observed to arise either from the dendritic trunk or from the soma.

The neuronal structure of the substantia nigra in the guinea pig: Nissl and Golgi study.

The studies were carried out on the mesencephalos of adult guinea pigs. The preparations were made by means of the Golgi technique, as well as the Nissl and Klüver-Barrera methods. Four types of neurons were distinguished in the substantia nigra (SN) of the guinea pig: 1. Bipolar neurons of two kinds: the neurons of the first kind have elongated, fusiform perikarya (25-40 microns), whereas the cells of the second kind have rounded and oval perikarya (15-22 microns). These neurons possess two dendritic trunks which arise from the opposite poles of the cell body and run for a relatively long distance. The bipolar neurons are the most numerous in the pars compacta of SN. 2. Triangular neurons with three primary dendrites arising conically from a perikaryon (20-35 microns). They are the most often observed type of neurons in the pars reticulata of SN. 3. Multipolar neurons with quadrangular or oval perikarya (22-35 microns) and 4-5 dendritic trunks which spread out in all directions. 4. Pear-shaped neurons (perikarya 15-25 microns), which have one or two primary dendritic trunks arising from one pole of the cell body. In all the types of neurons an axon originates either from the dendritic trunk or from the soma and is observed only in its initial segment.

The cytoarchitectonic and neuronal structure of the red nucleus in guinea pig: Nissl and Golgi studies.

The present studies were carried out on the brains of adult guinea pigs, Dunkin-Hartley strain. On the basis of preparations, they were stained according to the Nissl and the Klüver-Barrera method's; a short description of the cytoarchitectonics and the characteristics of the rubral cells were written. The red nucleus (RN) of the guinea pig is 1.2 mm in length. Three cellular parts in RN, and three classes (A, B, C) of the rubral cells were distinguished. Taking into consideration the predominant cell size, RN was divided into magnocellular part (RNm), parvocellular part (RNp) and intermediate part (RNi). On the basis of Golgi impregnated preparations four neuronal types (I, II, III, IV) were distinguished. To sum up, in the guinea pig were observed: the large, mainly multipolar (type I) and bipolar (type II) spiny being coarse (class A) in Nissl material; the medium-sized, triangular, aspiny (type III) corresponding to the fine cells (class B); and the small, both spiny and aspiny neurons (type IV), which are the fine or achromatic cells (classes B or C) in Nissl stained slices. The highest degree of dendritic branching was observed in type I, whereas the lowest in cells of types III and IV.

Types of neurons of the septal nuclei in the guinea pig: Golgi and Klüver-Barrera studies.

Four types of neurons were distinguished in the septum of the guinea pig: 1. Piriform neurons (perikaryons 20-25 microns) with two thick dendritic trunks and an axon which emerges from the perikaryon on the opposite side to the dendritic trunks. These neurons are the main type of cells in the investigated nuclei; 2. Triangular neurons (24-32 microns) with three thick dendritic trunks arising conically from the perikaryons and a thin axon emerging directly from the soma; 3. Fusiform neurons (35-40 microns) which have two thick dendritic trunks on both poles of the cell body and a thin axon emerging from the soma; 4. Multipolar neurons (30-35 microns) with 4-5 thick dendritic trunks which emerge conically from the perikaryon. The axon arises near one of the dendritic trunks.

Types of neurons of the subthalamic nucleus and zona incerta in the guinea pig--Nissl and Golgi study.

The studies were carried out on the subthalamus of adult guinea pigs. Golgi impregnation, Nissl and Klüver-Barrera methods were used for the study. In Nissl stained sections the subthalamic neuronal population consists of multipolar, fusiform, oval and pear-shaped perikarya. In two studied areas: nucleus subthalamicus (STN) and zona incerta (ZI) three types of neurons were distinguished. Type I, multipolar neurons with quadrangular, triangular or oval perikarya. They have 3-6 primary dendrites which run slightly wavy and spread out in all directions. Type II, bipolar neurons with fusiform or semilunar perikarya, they have two primary dendrites. Type III, pear-shaped neurons with 1-2 dendritic trunks arising from one pole of the neuron. In all types of neurons axon emerges from the perikaryon or initial segment of a dendritic trunk and can be followed at a maximum distance of about 50 microns.

The types of neurones in the neostriatum of the guinea pig (Cavia porcellus): Golgi and Klüver-Barrera studies.

The Golgi technique stain was used to reveal the cellular structure of the neostriatum (nucleus caudatus and putamen) in the guinea pig. The computerised reconstructions were made from Golgi impregnated neurones. On the basis of various criteria, 4 types of neurones were distinguished in the guinea pig neostriatum: 1. The rounded neurones (most numerous) with 5-8 thin dendritic trunks; 2. The triangular nerve cells with 3 thick dendritic trunks; 3. Two types of multipolar neurones differing in dendritic arborization pattern with 4-6 and 7-9 primary dendrites, respectively. 4. The pear-shaped cells, which divide into two distinctly different subpopulations.

The neuronal structure of paramamillary nuclei in Bison bonasus: Nissl and Golgi pictures.

The studies were carried out on the hypothalamus of bison bonasus aged 2 and 3 months. Sections were made by means of Baginski's technique and Nissl and Klüver-Barrera methods. Four types of neurons were distinguished in the paramamillary nuclei: nucleus supramamillaris (Sm) and nucleus tuberomammillaris pars posterior (Tmp). Type I, small and medium-size, triangular or fusiform cells, which have 2-3 slender, poorly ramified dendrites; typical leptodendritic neurons. Type II, medium size neurons with quadrangular or spindle-shaped perikaryons. Most of them have 3-4 thick dendritic trunks with ramifying relatively long dendrites. These cells show stalked-appearance and possess different appendages sparsely distributed. Type III is similar to type II, but is made of medium-size to large multipolar cells having quadrangular, triangular or fusiform perikaryons and relatively short dendrites. Type IV, small and medium-size, globular cells with 2 or 3 dendritic trunks, which dichotomously subdivide into quaternary dendrites. In all types of neurons, axons emerge from the perikaryon or initial portion of a dendritic trunk. Type I was found in both studied nuclei. Types II and III constitute mainly the nucleus tuberomamillaris pars posterior. Type IV preponderate in the nucleus supramamillaris. The characteristic feature of Tmp cells, in Nissl picture was irregular contour of their somas and clumps of rough Nisls granules, which appear to lie outside the perikaryons. In Sm there were also lightly stained small rounded cells having both small amount of the cytoplasm and tigroid matter.

Types of neurons in the nucleus ruber of the European bison. Klüver-Barrea and Golgi studies.

The studies were carried out on the mesencephalons of 4 European bison Preparations were made by means of Golgi impregnation and Klüver-Barrera method. Three types of neurons were distinguished in the red nucleus: 1. Large multipolar (perikaryons 70-105 microns) with 6-8 dendritic trunks which bifurcate twice and next give thin collaterals. 2. Small multipolar neurons (perikaryons 30-40 microns). These cells send 4-6 thick dendritic trunks. Most of the primary dendritic trunks bifurcate once. The remaining ones gives off only thin collaterals 3. Small triangular neurons (perikaryons 30-40 microns) with 3 thick dendritic trunks arising conically from perikaryons. Dendritic trunks bifurcate once near of the cell body. In all types of red nucleus neurons the axons arise directly from the surface of the perikaryons.

The types of neurons of the somatic oculomotor nucleus in the European bison. Nissl and Golgi studies.

The neuronal structure of the somatic oculomotor nucleus (SON) was studied on the basis of Nissl and Golgi preparations, obtained from mesencephalons of 4 European bisons. We distinguished four types of neurons in the investigated nucleus: 1. The large multipolar nerve cells with 5-8 thick dendritic trunks and a thin axon which emerges directly from the soma. These are the most numerous neurons in the SON. 2. The small multipolar neurons. These cells have 4-6 thick dendritic trunks. An axon arises mostly from initial segment of one of the dendrites. This type represents about 8% neurons of SON. 3. The triangular neurons. From perikaryon 3 thick dendritic trunks emerge. A thin axon arises directly from the cell body. These cells make about 10% neurons of SON. 4. The pear-shaped cells which have 1 or 2 dendritic trunks concentrate at one pole of the neurons. In the SON there are about 2% pear-shaped cells. Their features correspond to the features attributed by many authors to the interneurons.

Location and structure of the nuclei of epithalamus in hedgehog.

Studies were carried out on series of paraffin scraps stained by Nissl and Klüver-Barrera methods. Habenular complex in hedgehog divides into nucleus habenularis medialis (hm) and lateralis (hl). These centers are located between anterior edge of commissura posterior and about 180 microns in front of posterior edge of corpus callosum. Length of hm is about 2.75 mm. The medial habenular nucleus is compact, well formed and outlined group of heavily stained mainly round cells. It has diveresely placed a drop-like shape, for long distance. On the dorsal side of hm there are a small more intensively stained neurons that vary from the remaining ones. The lateral habenular nucleus is shorter and less demarcated than hm. On the cross-sections, area of hlisat least twice larger than hm but its cells are very dispersed among strong myelinated fibers This nucleus most often has the shape of vertical or oblique band of neurons that generally are larger, paler stained and heteromorphic.

The neuronal structure of globus pallidus in bison bonasus: Nissl and Golgi study.

The two subnuclei of globus pallidus have been investigated in the telencephalon of bison bonasus. The Nissl and Golgi procedures have been used to reveal their cellular organization. The Golgi preparation suggests the existence of two fairly divergent cellular subpopulations. The first class comprising the bulk of pallidal neurons consists of large efferent cells with long thick infrequently branching dendrites. The morphology of their dendritic processes is very complex and variable even in the one neuron (complex terminal endings, thin dendritic appendages, spiny segments, aspiny segments). Some of these structures (i.e. terminal endings, thin appendages) seem to be of presynaptic nature and allow one efferent neuron to influence on the functions of other large pallidal cells (interneuronal functions). The second one is composed of small interneurons with short highly arborized axons and thin varicose dendritic processes. Their distribution is very sparse and irregular in both segments of investigated nucleus.

Neurons of the substantia nigra in the European bison.

The studies were carried out on the mesencephalons of four European bisons with two different Golgi procedures and stained according to the Nissl and Klüver-Barrera methods. Four types of neurons were distinguished in the substantia nigra of the European bison. Type I are fusiform cells which are most numerous in pars compacta of SN. From each pole of the perikaryon originate 1-3 dendritic trunks. The axon arises from the base of dendritic trunk or directly from the lateral surface of the perikaryon. Type II are triangular cells which are most numerous in pars reticularis of SN. The neurons give off 3 primary dendrites. The axon arises mostly from the base of dendritic trunk. Type III are large multipolar neurons with 4-5 thick dendritic trunks. The axon emerges directly from the surface of the perikayon. Type IV are piriform and rounded cells. They have two thick primary dendrites, which leave the cell body at one pole of the neuron. The thin axon emerges from the cell body near the dendrites.