Parathyroid hormone-related peptide is a potent tumor angiogenic factor

Rat pituitary malignant tumor cells; mGH3, show hypervascularization in in vivo xenografts and overexpress parathyroid hormone-related peptide (PTHrP) compared to original GH3 cells. To elucidate whether PTHrP is involved in tumor-derived angiogenesis, we examined the effect of PTHrP on vascular endothelial cells both in vitro and in vivo. Results of in vivo diffusion chamber assay showed a clear hypervascularization on the outer surface of diffusion chambers containing mGH3 tumor cell implants but not in those containing GH3 cells. Co-incubation with antisense PTHrP oligonucleotide (10 microM), but not sense or mismatched PTHrP oligonucleotide, suppressed hypervascularization in diffusion chambers. To further examine the role of PTHrP on endothelial cell function, PTHrP(1-34) was added at various concentrations to cultured bovine endothelial cells (BAECs) harvested from the aorta. PTHrP(1-34) did not alter the proliferation or migration of endothelial cells, but rather dose-dependently increased capillary formation by endothelial cells on the collagen gel matrix. Furthermore, 0.1 mM of 8-bromo-cAMP caused a similar increase in tube formation, which was dose-dependently inhibited by H89, a protein kinase A inhibitor. Our results indicate for the first time that PTHrP is a potential paracrine factor acting via the PKA pathway to enhance angiogenesis through capillary tube formation by endothelial cells in malignant pituitary tumors.

Neuronal organization of the optic tectum in the river lamprey, Lampetra japonica: a Golgi study

The neuronal and laminar organization of the optic tectum (OT) in the river lamprey was studied using the rapid Golgi method. Based primarily on the distribution pattern of the dendrites, the OT neurons were divided into vertical, horizontal and stellate neurons. The river lamprey OT shows a laminar structure consisting of eight concentric strata. The stratum ependymale consists of several rows of ependymal cells. The stratum cellulare periventriculare contains one to two rows of vertical neurons. The stratum fibrosum periventriculare is thin and contains a few vertical neurons. The stratum cellulare et fibrosum internum consists of several alternating cellular and fibrous layers: a large variety of vertical and horizontal neurons are distributed in this stratum. The stratum fibrosum centrale consists of compact horizontal fiber bundles, among which a few horizontal neurons are disseminated. In the stratum cellulare et fibrosum externum, numerous fibers run horizontally in a loosely organized plexus; various types of vertical, horizontal and stellate neurons are distributed among these fibers. The stratum opticum is the main terminal area of the optic nerve, and contains stellate and horizontal neurons. The stratum marginale is a thin layer and consists of sparse populations of vertical and horizontal neurons. Besides the above outer to inner laminar structure, the OT is divided into medial (m-OT) and lateral parts (1-OT), based primarily on the distribution pattern of the dendrites. The dendrites of neurons in the m-OT are distributed almost exclusively within the OT. On the other hand, the dendrites of some neurons in the 1-OT extended into the confines of the torus semicircularis (TS), and conversely, the dendrites of some neurons in the TS are distributed in the 1-OT. These findings are discussed in relation to the neuronal and laminar organization of the OT in other lamprey species and to recent hodological studies.

Neuronal organization of the olfactory bulb in the hagfish, Eptatretus burgeri: a Golgi study

The neuronal organization of the olfactory bulb (OB) in the hagfish (Eptatretus burgeri) was studied using the rapid Golgi method. Cytologically, two groups of cells, the mitral and stellate cells, were discernible in the OB. Cytoarchitecturally, the OB showed a distinct laminar structure. From the periphery inward, the following four strata were distinguished: the stratum nervosum, stratum glomerulosum, stratum mitrale and stratum stellatum. Olfactory fibers from the olfactory epithelium reach the rostral aspect of the OB and form the stratum nervosum. The olfactory fibers run deeply in the OB, enter the stratum glomerulosum and terminate in the olfactory glomeruli which are arranged in three to four rows. Numerous mitral and a few stellate cells are distributed in periglomerular areas. The dendrites of the mitral cells terminate in one to two glomeruli in tufted terminals, while those of the stellate cells are distributed in periglomerular areas. The stratum mitrale also consists of mitral and stellate cells. The mitral cells in this stratum extend long dendrites to 4-5 widely separated glomeruli and generate axons traveling caudally. The dendrites of the stellate cells are long and are distributed in the stratum glomerulosum and stratum stellatum, as well as within the stratum mitrale. The stratum stellatum occupies a narrow caudal area and consists mainly of stellate cells extending long dendrites to the stratum stellatum and stratum mitrale.

Neuronal organization of the spinal cord in the red stingray (Dasyatis akajei: chondrichthyes)

The neuronal organization of the spinal cord in red stingray was studied using the rapid Golgi method. The gray matter of the spinal cord was divided into seven laminae: RS-I, RS-II, RS-III, RS-IV, RS-V, RS-VI and RS-VII. RS-I is cell dense lamina which occupies the major part of the dorsal horn and corresponds to laminae I and II of the spinal cord of mammals, birds and reptiles. The neurons of the lamina I are interspersed with those of lamina II, without forming a discrete lamina. RS-II is located at the base of the dorsal horn and is considered to correspond to the nucleus proprius. RS-III and IV form the intermediate zone and are highly reticulated. A few neurons of various shapes and sizes are distributed among the numerous fibers. The nuclei such as the intermediolateral, intermediomedial or Clarke's nucleus cannot be identified in the intermediate zone. RS-V and VI constitute the ventral horn. RS-V occupies the major part of the ventral horn and contains motoneurons which are distributed diffusely, without forming any distinct cell groups. RS-VI is located in the ventromedial part of the ventral horn, contains commissural neurons and correspond to lamina VIII. RS-VII is a small area surrounding the central canal and corresponds to lamina X. Thus, while the major features of the spinal cord of the red stingray can be correlated with those of the spinal cord of mammals, birds and reptiles, the neuronal organization of the spinal cord of the red stingray remains in an undifferentiated state.

Distribution of the parathyroid hormone-related peptide and its receptor in the saccus vasculosus and choroid plexus in the red stingray (Dasyatis akajei: Elasmobranch)

1. The exact role of the parathyroid hormone-related peptide (PTHrP) is not fully understood. We used immunohistochemistry to localize the PTHrP and its receptor in the brain of the red stingray, particularly in the saccus vasculosus (SV) and choroid plexus. 2. Immunoreactive PTHrP and its receptor were detected in the epithelial cells of the SV and the choroid plexus. In addition, the neuronal perikarya in the nucleus of the SV located in the hypothalamus is positive for the PTHrP. 3. No PTHrP-containing neurons were detected in the choroid plexus. Extracts of SV and choroid plexus showed positive reactions against the PTHrP and its receptor antibody in Western blot analysis. 4. High levels of immunoreactive PTHrP were detected in the plasma equivalent to those present in human humoral malignant hypercalcemia. In contrast, the immunoreactive PTHrP concentration in the cerebrospinal fluid was below detectable levels. 5. Our results suggest that the regulation of the PTHrP in the SV differs from that in the choroid plexus in the red stingray.

Neuronal organization of the optic tectum in the hagfish, Eptatretus burgeri: a Golgi study

The neuronal organization of the optic tectum (OT) was studied in the hagfish using the rapid Golgi method. The OT shows laminar structure. Beginning from the ventricular surface, the following four concentric strata are discernible: the stratum ependymale, stratum periventriculare, stratum cellulare et fibrosum, and stratum marginale. The stratum ependymale consists of several rows of ependymal cells and neuroblasts lining the mesencephalic ventricle. The stratum periventriculare contains medium-sized and small neurons whose dendrites extend mainly superficially. The stratum cellulare et fibrosum occupies a wide area and consists of densely packed neurons and fibers. Fibers in this stratum are derived mainly from the bulbar lemniscus and run ventrodorsally in several bundles, among which numerous neurons are embedded. Neurons in the stratum cellulare et fibrosum are divided into large, medium-sized and small neurons whose dendrites are arranged in a network rather than being oriented in any particular direction. Some of these dendrites extend contralaterally through the commissure of the OT. The neurons in the stratum marginale are divided into medium-sized and small neurons whose dendrites extend mainly tangentially. The axons of neurons in the stratum periventriculare and those of a few neurons in the stratum cellulare et fibrosum extend rostromedially and can be traced into the stratum periventriculare. On the other hand, the axons of neurons in the stratum marginale and stratum cellulare et fibrosum run rostrally, turn ventrally and join fiber bundles running dorsoventrally.

A Golgi study on the nucleus sphericus of the striated snake, Elaphe quadrivirgata

The intrinsic organization of the nucleus sphericus (NS) was studied in the striated snake using the rapid Golgi method. The NS is a large aggregation of cells located in the posterior portion of the telencephalon and is, as a whole, cup-shaped with its hilus oriented in the rostral direction. From the periphery inward, the following three concentric layers were discernible: a marginal layer, mural layer and hilar layer. The marginal layer consists of scattered cells extending dendrites internally toward the hilar layer and externally into the anterior commissure (AC). The mural layer contains densely packed polygonal neurons with dendrites extending internally into the hilar layer and externally toward the marginal layer. The hilar layer consists of scattered cells whose dendrites extend in a transverse direction, distributing mainly in the hilar layer. The axons of the neurons in the marginal and mural layers travel rostromedially, and some axons can be traced into the AC, while those of the neurons in the hilar layer run rostrally, and some are lost among fibers of the accessory olfactory tract (AOT). The afferents to the NS are derived mainly from the AOT and AC. The AOT fibers travel caudally in a thick bundle through the hilus and are distributed totally within the hilar layer, forming a dense fiber plexus. The AC fibers enter the nucleus from the rostromedial aspect and run in an arched course, emitting numerous fine short collaterals.

Terminal patterns of the tegmental afferents in the interpeduncular nucleus: a Golgi study in the mouse

The intranuclear course, distribution and termination of the tegmental afferents in the interpeduncular nucleus (IP) were studied in the mouse by means of the rapid Golgi method. Primarily on the basis of terminal branching patterns and distribution areas, two types of afferents were distinguished. The type 1 fibers distribute mainly within the rostral half in the form of numerous glomerular endings, the size of which corresponds well with that of the tufted terminal dendrites of the IP neurons. On the other hand, the caudal half of the IP has far fewer fibers than the rostral IP and is innervated by the type 2 fibers, which follow a tortuous course, terminating in dense fiber plexus. Thus, the rostral and caudal IP are innervated in a different fashion by different afferents originating from tegmental regions. These results are discussed in relation to the distribution patterns of another conspicuous afferent system of the IP, the fasciculus retroflexus.

Terminal patterns of the fasciculus retroflexus in the interpeduncular nucleus of the mouse: a Golgi study

The courses and terminal patterns of the fasciculus retroflexus (FR) in the interpeduncular nucleus (IP) were studied in the mouse, using the rapid Golgi method. Mainly on the basis of the distribution areas and terminal patterns, the FR fibers are divided into two types. The type 1 FR fibers are coarse in contour and take zigzag courses to distribute throughout the entire rostral half and core region of the caudal IP. In contrast, the type 2 fibers are fine, travel caudally along the lateral boundary of the IP and terminate in the lateral regions of the caudal half, forming a dense fiber plexus. The distribution areas of the type 1 and type 2 fibers are clearly differentiated from each other, from the cytoarchitectural as well as the fibroarchitectural viewpoint. Thus, the type 1 and type 2 FR fibers form different fiber systems in the IP. These results are discussed in the light of the known hodological, histochemical and ultrastructural studies.

Differentiation of the brain stem structures in the salamander, Hynobius nebulosus

Differentiation of the internal structure of the brain stem was analyzed in the salamander with special reference to neurons distributed in the marginal layer. It was found that the salamander brain stem was at first composed exclusively of the mantle layer. The marginal layer later differentiated peripherally. In these developmental stages, the mantle and marginal layers were clearly differentiated: the former was made up exclusively of the somata, while the latter was composed mainly of nerve fibers. As the development proceeded, these organization patterns were modified: a few cells migrated into the marginal layer. Cells migrating into the marginal layer formed various nuclei and layers such as the raphe nuclei, reticular formation and superficial cellular layers of the optic tectum. In later development stages, fibers in the marginal layer were myelinated, and neurons in the marginal layer were observed to become embedded among numerous myelinated fibers. Cytologically, the majority of neurons in early developmental stages were unipolar, extending a process peripherally into the marginal layer. In later developmental stages, neurons in a deep zone of the mantle layer remained unipolar, whereas those in the marginal layer and in the superficial zone of the mantle layer differentiated into multipolar cells. Thus, (1) the marginal layer differentiated peripherally as a cell free region; (2) cells in the mantle layer later migrated into the marginal layer, changing into multipolar neurons; (3) cells in the marginal layer formed reticular formation as well as various nuclei and layers in the peripheral white matter; and (4) as development proceeded, fibers in the marginal layer became myelinated.

A Golgi study on the olfactory bulb in the red stingray, Dasyatis akajei

The intrinsic organization of the olfactory bulb (OB) was studied in the red stingray using the rapid Golgi method. The OB is horse shoe-shaped, surrounding the equator region of the nasal capsule. As seen in the sagittal sections, the OB is round with the long olfactory peduncle extending from the dorsocaudal region and the olfactory fibers in a thick bundle entering from the rostroventral aspect. Although not so distinct, the following areas are distinguished. A rostroventral ovoid area adjacent to the entrance of the olfactory fibers consists exclusively of the olfactory fibers running in various directions. Dorsocaudal to the olfactory fiber area is a wide crescent region containing thin bundles of olfactory fibers, olfactory glomeruli, mitral cells and a few disseminated granule cells. A narrow crescent area made up of scattered granule cells is located dorsocaudally to the above wide crescent area. The outermost region consists of a fiber layer encapsulating the dorsal to caudal aspect of the OB. Thus, while the major constituents of the vertebrate OB are recognized, the lamination is very obscure.

A Golgi study on the afferent fibers to the habenular ganglion in the red stingray, Dasyatis akajei

Afferent fibers to the habenular ganglion (HG) were derived mainly from the stria medullaris thalami (SM), which was roughly divided into a dorsal and ventral bundle. In the left ganglion seen at the level of the rostrocaudal middle, the dorsal bundle gave off collaterals to the lateral habenular nucleus (LH) and dorsal subnucleus of the medial habenular nucleus (MH), while the ventral bundle innervated the intermediate and ventral subnuclei of the MH. On the other hand, in the right ganglion at the level of the rostrocaudal middle, the dorsal subnucleus of the MH was innervated by collaterals from the dorsal bundle of the SM, whereas in the intermediate and ventral subnucleus fibers from the ventral bundle were seen. In the left ganglion at the caudal level, the dorsal and ventral bundle extended medially and joined the same bundle of the opposite side to constitute a dorsal and intermediate component of the habenular commissure, respectively. A third component of the HC, a ventral component, was seen to run between the fasciculus retroflexus of both sides. As in the case of the rostral level, the dorsal bundle of the SM emitted collaterals to the LH and dorsal subnucleus of the MH, while the intermediate and ventral subnuclei of the MH were projected upon by collaterals from the ventral bundle of the SM. At the caudal level of the right ganglion, the dorsal bundle gave off collaterals to the dorsal subnucleus of the MH. In contrast, the LH and the intermediate and ventral subnuclei of the MH were innervated by fibers from the ventral bundle. With regard to terminal patterns of the SM, fibers to the MH gave off many short fine branchlets forming the glomerular structures, whereas those to the LH branched out into numerous terminals to form a dense fiber plexus. Thus, the afferent fibers to the HG in the red stingray exhibited a striking left-right asymmetry.

A Golgi study on the neuronal organization of the habenular ganglion in the red stingray, Dasyatis akajei

The neuronal organization of the habenular ganglion (HG) was studied in the red stingray using the rapid Golgi method. The HG was made up of the medial (MH) and lateral habenular nucleus (LH), and the former nucleus was further divided into a dorsal, intermediate and ventral subnucleus. Only one type of neurons were observed in the MH, while the LH was composed of two types of neurons. In the left HG cut at the rostrocaudal middle of the ganglion, the LH was located in the dorsolateral region, while the dorsal, intermediate and ventral subnuclei of the MH occupied the dorsomedial, intermediate and ventral portions of the ganglion, respectively. In contrast, the right ganglion seen at this level was composed exclusively of the MH, with the dorsal, intermediate and ventral subnuclei located in the dorsomedial, intermediate and ventral portions, respectively. In the caudal level of the left ganglion, each nucleus was seen almost in the same region as in the level of the rostrocaudal middle, however, three subnuclei of the MH fused with the same subnuclei of the opposite side. In the right ganglion at the caudal level, the LH appeared in the intermediate area. The right LH was far smaller and was located more ventrocaudally than the left LH. On account of the LH, the intermediate subnucleus of the MH was divided into a dorsal and ventral part. The dorsal and ventral subnuclei of the MH remained in the same region as in the rostral level. Thus, the HG of the red stingray exhibited a striking left-right asymmetry, the most remarkable aspect of which was considered to be differences of the size, form and location of the LH between the left and right HG.

A Golgi study on the red nucleus in the mouse

The intrinsic organization of the red nucleus (RN) was studied in the mouse using the rapid Golgi method. Cytoarchitecturally, the RN was divided into the magnocellular (RNmc) and parvocellular parts (RNpc). The former occupied the caudal one-third and the latter formed the rostral two-thirds of the RN. Based primarily on the size of somata, the RN neurons were classified into four types: giant, large, medium-sized and small neurons. Of these, the former two types of neurons were distributed mainly in the RNmc, while the latter two types of neurons were seen mainly in the RNpc. Axons of the RN neurons, at least those of the former three types of neurons, ran medially or caudomedially. Some axons ran across the mesencephalic raphe region to be lost in the medial region of the contralateral tegmentum. Two groups of afferent fibers to the RN were distinguished. Group I afferents were fibers composing the superior cerebellar peduncle. After crossing in the decussation of the superior cerebellar peduncle, these fibers entered the RN from the caudomedial aspect, ran rostrally in the nucleus emitting numerous collaterals. Group II afferents reached the RN from the ventrolateral aspect and traveled mediodorsally to be distributed totally within this nucleus.

Differentiation of the brain stem reticular formation in the triturus, Triturus pyrrhogaster

The brain stem of the triturus was observed to be initially composed exclusively of the mantle layer. A few days before hatching, a narrow marginal layer differentiated peripherally. At the time of hatching, the marginal layer was clearly visible throughout the brain stem, except for in a medial region of the optic tectum. Approximately one week after hatching, a few cells migrated into the marginal layer, and almost simultaneously, a few fibers in that layer were myelinated. Cells migrating into the marginal layer formed reticular neurons as well as the raphe nuclei and superficial cellular layers of the optic tectum. As the development proceeded, the number of myelinated fibers in the marginal layer increased, and cells in that layer, especially reticular neurons, were seen to be embedded among numerous myelinated fibers, assuming the characteristic features of the reticular formation.

A Golgi study on the accessory olfactory bulb in the snake, Elaphe quadrivirgata

The intrinsic organization of the accessory olfactory bulb (AOB) in the snake was studied using the rapid Golgi method. A distinct laminar organization was observed in the snake AOB. Beginning with the most superficial surface, the following layers were distinguished: the layer of the vomeronasal fibers, the olfactory glomeruli, the mitral cells, the deep fiber plexus, the granule cells and the ependymal cells. While the general organizational pattern of the snake AOB resembles that of the main olfactory bulb (MOB) and the AOB reported in various vertebrate species, the present study shows that: (1) the external and internal plexiform layers cannot be identified as independent layers and are considered to be included in the mitral cell layer; (2) the afferent and efferent paths, which are disseminated in the granule cell layer in the mammalian MOB, accumulate external to the granule cell layer to form the layer of the deep fiber plexus: and (3) as a result of accumulation of the afferent and efferent paths in the layer of the deep fiber plexus, the granule cell layer is very fiber-sparse. These structural patterns are quite similar to those of the snake MOB.

A Golgi study on the main olfactory bulb in the snake Elaphe quadrivirgata

The intrinsic organization of the main olfactory bulb in the snake was studied using the rapid Golgi method. A distinct laminar structure was recognized. From the periphery inward, the following layers were distinguished: the layer of the olfactory fibers, the olfactory glomeruli, the mitral cells, the deep fiber plexus, the granule cells and the ependymal cells. Olfactory fibers derived from the nasal cavity reached the entire surface of the bulb, forming a dense fiber plexus, then swung deeply and terminated in the olfactory glomeruli which were arranged in 2-4 rows. The mitral cell layer occupied a wide zone and was composed of scattered mitral cells. The mitral cells had 2-9 primary dendrites proceeding externally to terminate in the olfactory glomeruli and 2-4 secondary dendrites extending tangentially in the mitral cell layer to be distributed therein. The axons of the mitral cells travelled deeply and entered the layer of the deep fiber plexus. The deep fiber plexus was the path for the bulbar efferent and afferent fibers and could be traced caudally as the main olfactory tract, up to the anterior olfactory nucleus and vicinity. The granule cell layer was composed of small cells, the granule cells, packed closely with no special arrangement. The granule cells had long processes which extended superficially to be distributed mainly in the mitral cell layer. The ependymal cells were located at the deepest layer forming the wall of the olfactory ventricle and generated a long process which extended towards the surface to terminate in the peripheral portion of the bulb. In the snake bulb, the well-documented external and internal plexiform layers were considered to be included in the wide mitral cell layer. Thus, while several specific structures were observed, the fundamental organization of the main olfactory bulb in the snake seemed to be identical to that of the main olfactory bulb in various other vertebrate species.

A Golgi study on the inferior olivary nucleus in the red sting ray, Dasyatis akajei

The intranuclear organization of the inferior olivary nucleus (ION) was studied in the red sting ray, using the rapid Golgi method. The ION neurons had polygonal, triangular or spindle cell bodies which generated 3-5 primary dendrites. These dendrites were relatively straight, sparsely spinous, and distributed mainly within the ION. The axons of the ION neurons extended medially and joined fiber bundles which ran transversely in the ION. Three groups of olivary afferents were distinguished: fibers derived from the tegmental area travelled ventrally and ended totally in the ION, composing a dense fiber plexus; collaterals of fibers which extended in a longitudinal direction in and around the ION distributed mainly in the lateral portion of the ION; and collaterals of fibers which ran transversely in the ION also ended in the ION. Some fibers from these 3 afferent groups converged to form pericellular baskets. Thus, the fundamental organization of the ION in the red sting ray was similar to that of the ION in mammals.

A Golgi study on the olfactory bulb in the lamprey, Lampetra japonica

The intrinsic organization of the olfactory bulb in the lamprey was studied using the rapid Golgi method. Although not as discrete as in many vertebrates, a laminar organization was recognized. From the periphery inward, the following layers were discernible: the layer of the olfactory fibers, the olfactory glomeruli with the mitral cells, the granule cells, and the ependymal cells. Just beneath the surface of the olfactory bulb, the olfactory fibers extended over the entire bulb forming a dense fiber plexus terminating in the olfactory glomeruli which were arranged in one to two layers internally to the layer of the olfactory fibers. The mitral cells formed no discrete layer and were located mainly around the olfactory glomeruli. The mitral cells in the lamprey were lacking in secondary dendrites, but had two or more primary dendrites which terminated in the olfactory glomeruli. The axons of the mitral cells proceeded inwardly and accumulated diffusely in the granule cell layer which occupied a wide area internally to the layer of the olfactory glomeruli with the mitral cells. The granule cell layer was composed of densely packed small spindle or fusiform axonless cells, the processes of which extended superficially to be distributed in the olfactory glomeruli. At the deepest region of the bulb was a layer of the ependymal cells lining the surface of the olfactory ventricle. The external and internal plexiform layers were not evident. Thus, while the major constituents of the olfactory bulb of the vertebrate could be identified in that of the lamprey, the general laminar organization seemed indiscrete.

A Golgi study on the neuronal organization of the neostriatum in the mouse

The neuronal organization of the neostriatum in mice was studied, using the rapid Golgi method. Based on the size of the somata, the neostriatal neurons were divided into groups of large, medium-sized and small cells, and the neurons of each group were further divided into 2-5 types, according to the shape of the somata and dendritic morphology. Three types of large neurons were recognized. Large type I neurons were triangular, piriform or fusiform cells with a few thick dendrites, whereas large type II and type III neurons were round or polygonal cells with numerous slender dendrites. The dendrites of the large type II neurons were far longer than those of large type III. Medium-sized neurons were grouped into 5 types. Medium type I neurons were round with spiny dendrites and were found mainly in the caudal portion of the neostriatum. Medium type II neurons had numerous thin dendrites and were predominant in the rostral portion of the neostriatum. Some medium type II neurons were arranged in cell chains extending perpendicular to Wilson's pencils. The cell bodies of medium type III neurons were triangular, and generated long spiny dendrites. Medium type IV neurons were polygonal, and dendrites with numerous short branchlets were evidenced. Medium type V neurons had poorly branched and sparsely spinous dendrites. The small neurons were of two types: small type I had piriform cell bodies, which gave rise to very thin dendrites, while small type II had dendrites with irregular contours and filiform appendages. Of these, the large type I and type II, the medium type I-V, and the small type I neurons seemed to be the projection neurons, whereas the large type III and small type II neurons were merely internuncials. Thus, the neostriatum in the mouse was shown to be composed of a wide variety of projection neurons and only two types of interneurons.

A Golgi study on the dorsal nucleus of the lateral lemniscus in the mouse

The dorsal nucleus of the lateral lemniscus (DLL) in the mouse was studied using the rapid Golgi method. Three types of neurons were observed in the DLL. Type I neurons had a piriform or triangular cell body with a mean diameter of 14 by 19 micron, and emitted 3-5 primary dendrites. The cell bodies of type II neurons were either spindle or piriform in shape and were, on the average, 17 by 26 micron in diameter with 2-4 primary dendrites. Type III neurons had polygonal or triangular cell bodies which were 24 by 31 micron in average diameter and there were 4-6 primary dendrites. The axons of the DLL neurons most frequently traveled medially or ventromedially, and only a few could be followed dorsally among the fibers composing the lateral lemniscus (LL). The afferent fibers of the DLL were separated into three groups: ascending afferents, descending afferents and afferents from the medial aspect. The ascending afferents were collaterals of the LL fibers distributed mainly in the inferior colliculus. The descending afferents were also collaterals arising from the descending LL fibers. The afferents from the medial aspect ran across the tegmental area to distribute in the DLL. In addition, numerous LL fibers gave off terminal collaterals to the DLL. The ascending or descending nature of these LL fibers was not determined. Thus, the DLL is considered to be one of the commissural relay nuclei in the auditory system.

A Golgi analysis of the accessory optic fibers terminating in the medial terminal nucleus of the mouse accessory optic system

Fibers of the accessory optic tract (AOT) terminating in the medial terminal nucleus (MTN) were observed in the mouse by the rapid Golgi method. The AOT fibers, which entered the MTN from its ventromedial aspect, were divided into thick and fine fiber groups, the thick fibers emitting many terminal collaterals of various calibers, and the fine ones generating fine terminal branches. The possibility exists that the retinal neurons sending AOT fibers to the MTN might be heterogeneous in nature.

Histopathologic study of congenital aural atresia in the human embryo

We studied the histopathologic features of the temporal bones in a human embryo with unilateral aural atresia. The developmental stage of the embryo was at stage 22 in the Carnegie system, and the estimated ovulation age was 8 weeks. There were severe hypoplastic changes in Meckel's and Reichert's arch cartilages without differentiation of the auditory ossicles, hypoplasia of the tubotympanic recess, and resultant abnormal passing of the facial nerve in the affected ear. Abnormal lateral extension of the cartilaginous otic capsule replaced a posterior half of the middle ear region and seemed to form the so-called atresia plate. The external and middle ears of the unaffected side and the bilateral inner ears were morphologically normal. These findings might explain some parts of the complicated mechanism in the development of middle ear anomalies encountered in surgery for congenital aural atresia.

A Golgi study on the globus pallidus of the mouse

The globus pallidus (GP) of the mouse was studied by the rapid Golgi silver impregnation method. The GP was composed of large and medium-sized neurons. The large neurons had stellate cell bodies with a mean diameter of 25 micron by 28 micron and five to seven primary dendrites. The somata of the medium-sized neurons were spindle or fusiform in shape, measured 19 micron by 27 micron in average and emitted three to five primary dendrites. The large neurons were located mainly in the central part of the GP, whereas the medium-sized neurons were observed in the peripheral part of the GP. Some GP neurons extended their dendrites into the caudatoputamen complex, sublenticular region or internal capsule. The axons of the GP neurons were seen most frequently to course medially or mediocaudally and to enter the internal capsule or fiber bundles traversing the GP; they were rarely observed to run laterally and to travel into the caudatoputamen complex. Some axons of the GP neurons were also observed to emit intra- or extra-nuclear collaterals extending into the sublenticular region. Four groups of afferent fibers to the GP were observed; (1) fibers descending within the internal capsule or caudatoputamen complex to terminate or to give axon-collaterals to the GP; (2) fibers ascending within the internal capsule or fiber bundles traversing the GP to enter the GP from its medial aspects; (3) fibers traversing the internal capsule laterally to terminate in the GP; and (4) fibers running dorsally through the sublenticular region to terminate in the GP. In addition to these four groups of afferent fibers, terminal branches were seen to arise numerously from many fibers running through the GP.

A Golgi study on the neuronal organization of the interhemispheric cortex in the mouse

The intrinsic neurons in the interhemispheric cortex (IHC) were studied by the rapid Golgi method in the young mouse. In each of the five layers of the IHC, a wide variety of intrinsic neurons were observed. They were classified into several groups according mainly to the patterns of axonal and dendritic distribution. The Cajal-Retzius cells were most frequently seen in layer I. The dendrites and axons of these neurons ran irregularly in the plane parallel to the pial surface of the IHC. Many neurons in layers II-V were observed to send their axons to layer I. Some of these neurons took the form of the inverted pyramidal neurons. The axons of some neurons in layers II, III and IV formed dense axonal plexuses usually in layer III and rarely in layer II. The dendrites of many neurons in layers IV and V extended into the cingulum. The stellate neurons embedded in the cingulum might be the dislocated neurons of layer V.

A Golgi study on the neuronal organization of the interhemispheric cortex in the mouse. I. Projection neurons

Projection neurons in the interhemispheric cortex (IHC) of the mouse were studied by the rapid Golgi method. Five layers were discerned in the IHC. Projection neurons in layer I had stellate or piriform cell bodies with dendrites which were distributed in layers I and II. The cell bodies of projection neurons in layer II were fusiform, piriform, triangular or stellate in shape. Fine axons of these neurons sent collaterals mainly to layer IV. Projection neurons in layer III were medium-sized pyramidal, and small spindle cells. Basal dendrites of the former neurons were distributed mainly in layer III, while those of the latter neurons extended into layer IV. Projection neurons in layer IV were largely pyramidal, medium-sized pyramidal, medium-sized fusiform, and small cells. In the large pyramidal cells, the basal dendrites were distributed mainly in layer IV, and the apical dendrites extended into layer I. The axons of these neurons sent collaterals to all cortical layers. In layer V, spindle and small stellate projection neurons were observed. All apical dendrites of projection neurons in layers I-III extended into layer I, whereas some apical dendrites of projection neurons in layers IV and V did not reach layer I.

Topographical representation of the hypoglossal nerve branches and tongue muscles in the hypoglossal nucleus of macaque monkeys

Representation of the hypoglossal nerve branches and tongue muscles was examined in the hypoglossal nucleus of macaques by the horseradish peroxidase method. The nucleus was divided cytoarchitectonically into the medial and lateral divisions at rostral levels, and into the mediodorsal, medioventral, ventral and laterodorsal divisions at caudal levels. The medial, mediodorsal, medioventral and ventral divisions supplied the medial branch. The lateral and laterodorsal divisions supplied the lateral branch. The geniohyoid motoneurons (MN) composed the ventral division. The genioglossus MN were clustered dorsally in the medial division. The hyoglossus and styloglossus MN were located most laterally in the laterodorsal division.

A Golgi study on the bed nucleus of the ansa lenticularis in the mouse

The bed nucleus of the ansa lenticularis (BNAL) was studied by the rapid Golgi method in the mouse. It was composed of large and small neurons; the latter were the main constituents. Dendrites of the BNAL neurons were distributed only within the confines of the ansa lenticularis (AL). Axons of BNAL neurons ran ventromedially or dorsolaterally along the AL. Terminal fibers in the BNAL arose from fine collaterals of fibers running in the ventral portions of the lentiform nucleus.

Representation of the masticatory muscles in the motor trigeminal nucleus of the macaque monkey

The pattern of representation of the masticatory muscles in the motor trigeminal nucleus was examined in macaque monkeys by the horseradish peroxidase method. The motor trigeminal nucleus was divided cytoarchitectonically into the dorsolateral and ventromedial divisions. The temporalis, masseter and pterygoid muscles were represented in the dorsomedial, central and ventrolateral parts of the dorsolateral division, respectively. In the ventromedial division, which was located at the level of the caudal half of the nucleus. The anterior digastric or mylohyoid muscle was represented in the dorsomedial or ventrolateral part of the division, respectively.

A Golgi study on the subthalamic nucleus of the cat

The subthalamic nucleus (ST) of kittens was studied by means of the rapid Golgi silver impregnation method. The neurons of the ST were classified into three types. Type I neurons, the main constituents of the ST, had oval or polygonal cell bodies with a mean diameter of 26 micrometer by 36 micrometer and four to six primary dendrites. Type II neurons had multipolar or polygonal cell bodies, which measured an average 31 micrometer by 43 micrometer and emitted four to seven primary dendrites. The cell bodies of the type III neurons were polygonal in shape, measured 23 micrometer by 26 micrometer in average and emitted four to six primary dendrites. The dendrite bundle and the dendrite pallisade were observed. Frequently dendrites of the ST extended into the cerebral peduncle (CP), and even cell bodies of some ST neurons were located within the CP. All of the parent axons of the ST neurons coursed rostrally, although intra- and extra-nuclear axon-collaterals arising from the ST neurons travelled rostrally, caudally or caudomedially. The afferent fibers to the ST were divided into three groups; afferents via the Meynert's commissure (MC), decending and ascending afferents. The MC fibers, which ran across the CP, gave terminals to the ST. The descending afferents were axon-collaterals of fibers descending in the CP and those of fibers running through the ST. The ascending afferents were also axon-collaterals arising from ascending fibers in the CP. In addition to these afferents, many descending and ascending fibers of passage ran through the ST without emitting axon-collaterals.

A Golgi study on the habenular nucleus of the cat

The habenular nucleus of kittens was studied using the rapid Golgi and the Golgi-Kopsch silver impregnation methods. The neurons of the medial habenular nucleus (MH) were classified into two types. The type I neurons, the main constituents of the MH, had piriform cell bodies with a mean diameter of 12 mum by 18 mum and two to five primary dendrites; dendrites had many spines. The type II neurons (14 X 23 mum) were fusiform in shape and one to three primary dendrites arose from each pole of the cell bodies; dendrites had few spines. The axons of both types of neurons were traced into the fasciculus retroflexus Meynerti (FR), and intranuclear axon-collaterals arose from axons of the type I neurons. The neurons of the lateral habenular nucleus (LH) were divided into four groups. Type I, II and III neurons were projection neurons of large, medium and small size, respectively. The type I neurons (27 X 43 mum) with four to seven primary dendrites were located mainly in the rostral and ventral areas of the LH. The type II neurons (15 X 33 mum) with two to four primary dendrites, the main constituents of the LH, were distributed throughout the LH. The type III neurons (15 X 25 mum) with two primary dendrites emerging from each pole of the soma were localized to the mediocaudal areas of the LH. The vast majority of axons of these projection neurons passed ventrally or ventrocaudally to enter the FR; only a few axons of these neurons were traced into the stria medullaris thalami (SM). The type IV neurons (12 X 25 mum) were small cells with short axons, suggesting the existence of a neural circuitry intrinsic to the LH. Bundle formation and glomerular arrangement of dendrites were observed in the medium-sized LH neurons. The afferent fibers terminating within the MH coursed in the most part of the SM. These afferents were classified into medium-caliber type I and fine type II fibers; both of these fibers emitted many intranuclear collaterals. There were also observed many fibers of passage which ran between the SM and FR, or between the habenular commissure (HC) and FR. The afferent fibers to the LH were divided into three groups; afferents via the HC, ascending and descending afferents. Most of the descending afferents entered the LH through the SM; some of them traversed the LH to join the FR or HC, or to extend to the pretectal region. The vast majority of the ascending afferents entered the LH via the FR; some of them extended rostrally to enter the SM. Some fibers in the HC also terminated within the LH. In addition to these afferents, many fibers of passage were seen to run through the LH and to bridge over between the SM and FR, or between the SM and HC.