Variations in the number of human permanent teeth: hypodontia

The partial absence of teeth germs is a hereditaryor acquired congenital defect called hypodontia.The present report analyses and discusses hypodontiain permanent dentition on the basis ofeleven clinical cases. In these, the hypodontiacorresponded to mandibular central incisors,maxillary lateral incisors, maxillary canines, ormaxillary and mandibular premolars and molars.All these cases of hypodontia were recorded byphotographs of the oral cavity and/or by orthopantomographicstudies. Together with themost-frequent types of hypodontia already reportedin the literature, other unusual anomaliesthelack of permanent canines, central incisors,or molars - from both the maxillary andmandibular alveolar arches- were also detected (AU)

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Oral anatomical defects associated with cleft palate and cleft lip

Patients suffering from a cleft palate and/or cleftlip present evident anatomical defects in bothformations. However, these developmentaldisorders are often accompanied by importantdisturbances in other anatomical structures ofthe mouth and adjacent tissues that may affectnormal dental occlusion and, consequently, thebasic functions of mastication and phonation.The objectives of the present work were to describeand discuss the above structural modifications,presenting several clinical cases in whichthe anatomical defects are described togetherwith the functional implications. The anomaliesfound include important variations in the numberof teeth, the position, disposition and relationof the alveolar processes, and the impairmentof dental occlusion. In the cases studied,these anatomical defects have elicited prominentalterations in the normal functions of masticationand phonation, and also in facial aesthetics. Photographsof mouths, dental casts, and X-rays areused to illustrate our report

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Anatomical variations in the human paranasal sinus region studied by CT.

A precise knowledge of the anatomy of the paranasal sinuses is essential for the clinician. Conventional radiology does not permit a detailed study of the nasal cavity and paranasal sinuses, and has now largely been replaced by computerised tomographic (CT) imaging. This gives an applied anatomical view of the region and the anatomical variants that are very often found. The detection of these variants to prevent potential hazards is essential for the use of current of endoscopic surgery on the sinuses. In the present work, we have studied the anatomical variants observed in the nasal fossae and paranasal sinuses in 110 Spanish subjects, using CT in the coronal plane, complemented by horizontal views. We have concentrated on the variants of the nasal septum, middle nasal concha, ethmoid unciform process and ethmoid bulla, together with others of lesser frequency. The population studied showed great anatomical variability, and a high percentage (67%) presented one or more anatomical variants. Discounting agger nasi air cells and asymmetry of both cavities of the sphenoidal sinus, which were present in all our cases, the variations most often observed were, in order, deviation of the nasal septum, the presence of a concha bullosa, bony spurs of the nasal septum and Onodi air cells.

Heterogeneous distribution of cytochrome oxidase activity in the human substantia nigra pars compacta / Distribución heterogénea de la actividad de citocromo oxidasa en la pars compacta de la sustancia negra humana

The activity of the enzyme cytochrome oxidase has been analyzed in the human substantia nigra at light microscope level. The distribution of this activity is relatively uniform in the substantia nigra, except in the caudomedial region of the pars compacta, where a reduction was observed. This nigral zone matched a region characterized by its relatively high content of acetylcholinesterase activity. Our results are analyzed with reference to data in the literature, showing the existence of a neuroanatomical and functional subdivision within the pars compacta. Our findings add new proof of the known neurochemical heterogeneity of the nigral complex (AU)

La actividad de la enzima citocromo oxidasa ha sido analizada en la sustancia negra humana a nivel de microscopía óptica. La distribución de dicha actividad es relativamente uniforme en la sustancia negra, con excepción de la región caudomedial de la partes compacta, donde se aprecia una reducción. Esta zona nigral correspondía a una región caracterizada por el contenido relativamente alto en actividad acetilcolinesterásico. Nuestros resultados se analizan con referencia a los datos publicados en la literatura, mostrando la existencia de una subdivisión neuroanatómica y funcional dentro de la partes compacta. Los hallazgos aportan nuevas evidencias sobre la conocida heterogeneidad neuroquímica del complejo nigral (AU)

Skeletal maturation of wrist and hand ossification centers in normal Spanish boys and girls: a study using the Greulich-Pyle method.

The skeletal maturation of the upper limb distal segment was studied in 239 Spanish boys and girls between birth and 14 years of age. The atlas of Greulich and Pyle, offering standards of skeletal development of white North American children, was used as reference. The results obtained show firstly that in absolute terms, the ossification process is earlier in girls than in boys. This difference is maximum between 5 and 11 years of age. The boys show a delay of around 3 months with respect to their North American opposites. The girls, in contrast, show a better fit to the corresponding (female) standard of the atlas. In general, the highest agreement between bone age and chronologic age is for the ossification centers of the distal epiphysis of the ulna and radius and for those of the metacarpal bones. At the level of the carpus, individual analysis of the ossification centers shows that the capitate and hamate bones in the girls evolve most in accord with chronologic age. At the other extreme, and in both sexes, the ossification centers of the trapezium and trapezoid bones are statistically furthest from chronologic age.

Microsurgical anatomy of the human ophthalmic artery: a mesoscopic study of its origin, course and collateral branches.

In the present paper we have studied the gross (mesoscopic) anatomy of the ophthalmic a. in humans, using magnification by microsurgical systems to obtain data on the origin and course of this artery and its main collateral branches. Comparison of our results with previous reports indicates that, although the anatomical variations of the vascular system are well known, some patterns of frequency may be emphasised. Thus, the ophthalmic a. was usually found as a collateral branch of the internal carotid a., although other origins were also found. The ophthalmic a., once inside the orbit, followed a course above the optic nerve in most cases. All the collateral branches of the ophthalmic a., with the exception of the muscular branches, showed great constancy.

Anatomical study of the branches emerging along the intracavernous course of the internal carotid artery in humans.

The introduction in the sixties of magnification tools in surgery has created the need for a precise anatomical knowledge of morphological structures that was previously unnecessary from a clinical perspective. In the present paper, we have centred our attention on the intracavernous portion of the internal carotid artery (arteria carotis interna) in humans for applicative purposes. With the aid of a surgical microscope and the corresponding microdissecting material we have analysed the branches emerging from this arterial segment. Our results are compared with previous data appearing in the literature, the latter sometimes confusing because of the different terminologies used to refer to these vessels. The elements under study varied greatly, but some basic variational parameters were deduced.

Gross (mesoscopic) and applied anatomy of the anterior inferior cerebellar artery in man with special reference to its course through the cerebellopontine angle region.

In the present paper, we describe anatomical variants of the anterior inferior cerebellar artery in man for applicative purposes. Our goal was to provide the surgeon with a detailed anatomical view of the region. This is similar to what he may observe through the surgical microscope using modern microsurgical techniques. We have focused our attention on the segments of the artery comprising its origin, its course until it reaches the cerebellum and its main collateral branches. Our results confirm the great variability of the elements under study, but enable the establishment of a few basic variational patterns. These patterns together with their relative frequency may be helpful in microsurgery.

Nigrocaudate and nigroputaminal projections in the monkey.

Following injections of tracers into the caudate nucleus, the putamen or into both structures of the same cerebral hemisphere, retrograde cell labeling in the nigral complex of the squirrel monkey has been analyzed. Our goal was to investigate a possible relation of the retrograde neuronal labeling in the substantia nigra pars compacta (SNc) with the histochemical compartmentalization of this structure detected with the aid of the acetylcholinesterase (AChE) technique. Our results confirmed that in the squirrel monkey there was a very precise topography in the nigrostriatal projection system as a whole, and also in the nigrocaudate and nigroputaminal projection systems considered separately. In the cases with injections of two different tracers, we were not able to find any double-labeled nigral cell. Nigrocaudate and nigroputaminal projecting cells generally formed independent groups which at some nigral levels clearly interdigitated, as shown by the group of Parent. However, the presence of nigral cells labeled either by one or another tracer within the same histochemical compartment of the SNc confirmed that the segregation of nigroputaminal and nigrocaudate projecting cells did not explain the AChE compartmentalization of the SNc. Based on our experiments and on the literature we suggest that the histochemical compartmentalization of the SNc could be related, at least in part, to the subdivision of the striatum into AChE-poor striosomes and an AChE-rich extrastriosomal matrix.

Evidence that histochemically distinct zones of the primate substantia nigra pars compacta are related to patterned distributions of nigrostriatal projection neurons and striatonigral fibers.

A marked histochemical compartmentalization is visible in the substantia nigra of the squirrel monkey in sections stained for acetylcholinesterase (AChE). In nigral regions containing tyrosine hydroxylase-positive neurons, there are AChE-poor and AChE-rich zones, and many of the AChE-poor zones have the form of narrow fingers extending ventrally into an AChE-rich matrix (Jimenez-Castellanos and Graybiel 1987b). The study reported here was carried out to determine whether this histochemical heterogeneity of the primate's substantia nigra is related to the known differentiation within its pars compacta of subdivisions projecting respectively to the caudate nucleus and to the putamen. Retrograde and anterograde labeling in the substantia nigra was elicited by tracer injections placed in the caudate nucleus or putamen and was plotted in relation to patterns of AChE staining and tyrosine hydroxylase immunostaining. Much of the labeling observed was organized according to borders visible with AChE histochemistry: labeled nigral neurons (and afferent fibers) tended to be clustered precisely within the AChE-poor ventrally-extending fingers or to be situated outside these zones. However, projection neurons in these ventrally-extending fingers were not exclusively related either to the caudate nucleus or to the putamen. After injections in the caudate nucleus, labeled neurons were predominantly in the AChE-poor fingers in some cases, but predominantly in AChE-rich nigral zones outside them in other cases. Labeling in and out of the ventrally-extending fingers, and along the edges of the fingers, also occurred following different tracer injections in the putamen. These findings confirm the independent clustering of nigrostriatal neurons projecting respectively to the caudate nucleus and to the putamen. The plan of nigrostriatal connections additionally appears concordant with the histochemical compartmentalization of the substantia nigra that can be detected with acetylthiocholinesterase histochemistry.

Compartmental origins of striatal efferent projections in the cat.

Injections of the retrograde tracer, wheat germ agglutinated-horseradish peroxidase were placed in the substantia nigra, in adjoining dopamine-containing cell groups A8 and A10, and in the internal and external parts of the pallidal complex of 20 cats in order to identify the compartmental origins of striatal efferent projections to the pallidum and midbrain. Patterns of retrograde cell-labeling in the caudate nucleus were analysed with respect to its striosomal architecture as detected in sections stained for acetylcholinesterase. Where possible, a similar compartmental analysis of cell-labeling in the putamen was also carried out. In 15 cats anterograde labeling in the striatum was studied in the sections stained with wheat germ agglutinated-horseradish peroxidase or in autoradiographically treated sections from cases in which [35S]methionine was mixed with the wheat germ agglutinated-horseradish peroxidase in the injection solution. Predominant labeling of projection neurons lying in striosomes (usually with some labeling of dorsomedial matrix neurons) occurred in a subset of the cases of nigral injection, including all cases (n = 9) in which the injection sites were centered in the densocellular zone of the substantia nigra pars compacta [Jiménez-Castellanos J. and Graybiel A. M. (1987) Neuroscience 23, 223-242.] Dense labeling of neurons in the extrastriosomal matrix, with at most sparse labeling of striosomal neurons, occurred in all cases of pallidal injection (n = 8) and in two cases of nigral injection in which the injection sites were lateral and anterior to the densocellular zone. Mixed labeling of striosomal and matrical neurons occurred in a third group of cases in which the injection sites were lateral to the densocellular zone but close to it. In a single case with an injection site situated in the pars lateralis of the substantia nigra, there was preferential labeling of striosomal neurons in the caudal caudate nucleus but widespread labeling of neurons in both striosomes and matrix in the putamen. A second type of compartmental ordering of projection neurons was found in the extrastriosomal matrix of the striatum. In cases of pallidal and nigral injection, there were gaps in cell labeling that did not match striosomes precisely, and often clusters of labeled cells appeared that did not correspond to acetylcholinesterase-poor striosomes but, instead, to patches of matrix. Especially prominent were clusters beside striosomes. There was a topographic ordering of striatal projection neurons both in the striosomes and in the extrastriosomal matrix according to their dorsoventral and latitudinal positions.(ABSTRACT TRUNCATED AT 400 WORDS)

Topographical organization of the projections from the reticular thalamic nucleus to the intralaminar and medial thalamic nuclei in the cat.

The topography of the projections from the reticular nucleus of the thalamus (RT) to the intralaminar and medial thalamic nuclei were studied in the cat by the method of retrograde transport of horseradish peroxidase (HRP). Single small injections of the enzyme were made in the different intralaminar nuclei--mediodorsal, ventromedial, midline, and habenular--and in anterior group nuclei. The location and density of the neuronal labeling in the different parts of the RT were studied in each case. Our results show that 1) after injections located in all the nuclei here studied, a consistent number of labeled neurons were found in the RT, except for the injections in the lateral habenula and the anterior thalamic nuclear complex, both of which did not label neurons in the RT. 2) Among the other thalamic nuclei here studied, the most medially situated receive less numerous RT projections than those most laterally located. 3) Injections in all the nuclei studied gave rise to a cellular labeling in the anterior sectors of the RT, except for the anterior nuclear group and the lateral habenula. The projections from the rostral pole of the RT were topographically mediolaterally organized. 4) The anterodorsal part of the pregeniculate sector of the RT projects upon the large-celled part of the lateral central nucleus and to a lesser extent upon the paracentral, centromedian, and ventromedial nuclei, the anterior part of the lateral central nucleus, and the lateral band of the mediodorsal nucleus. The posterodorsal part of the RT pregeniculate sector only projects to the large-celled part of the lateral central nucleus. The dorsal portion of the posteroventral part of the RT pregeniculate sector also projects upon the large-celled part of the lateral central nucleus; its ventral portion projects to the ventromedial nucleus, the posterior part of the paracentral nucleus, the lateral band of the mediodorsal nucleus, and the centromedian nucleus. 5) The infrageniculate sector of the RT projects to the posterior part of the ventromedial nucleus. A weaker projection to the large-celled part of the lateral central nucleus, the centromedian nucleus, and the lateral band of the mediodorsal nucleus was also observed. 6) The ventral lateral geniculate nucleus projects upon the large-celled part of the lateral central nucleus, the lateral band of the mediodorsal nucleus, and the ventromedial nucleus. All these findings suggest an important modulatory action of the RT on the activity of the thalamic nuclei considered here.

Subdivisions of the primate substantia nigra pars compacta detected by acetylcholinesterase histochemisty.

Acetylcholinesterase-poor and acetylcholinesterase-rich compartments have been identified histochemically in the substantia nigra pars compacta of the squirrel monkey. Some of these compartments have clear correspondents in sections immunostained for tyrosine hydroxylase and in sections stained for Nissl substance. Clustering patterns of neurons retrogradely labeled after tracer injections either in the caudate nucleus or in the putamen were found to be related to these histochemical and cytoarchitectonic specializations of the substantia nigra pars compacta.

Subdivisions of the dopamine-containing A8-A9-A10 complex identified by their differential mesostriatal innervation of striosomes and extrastriosomal matrix.

The mesostriatal projections from the dopamine-containing cells groups A8, A9 and A10 have been studied in the cat in relation to the histochemical compartments known to exist in the striatum. In order to do this, we made stereotaxic injections in the substantia nigra of either [3H]proline-[3H]leucine, [35S]methionine, wheat germ agglutinin-horseradish peroxidase, or the two last tracers combined, and compared the location of anterograde labeling in the striatum to the locations of striosomes and extrastriosomal matrix identified by their low or high content, respectively, of the enzyme acetylcholinesterase. A discrete innervation of dorsolateral striosomes by a caudal densocellular subdivision of the substantia nigra pars compacta was found. This densocellular zone of the pars compacta was readily identifiable in sections stained for tyrosine hydroxylase-like immunoreactivity and corresponded to the uniquely acetylcholinesterase-poor zone detected in the substantia nigra pars compacta in serially adjacent sections stained for this enzyme. Selective anterograde labeling of the extrastriosomal matrix occurred in cases with injection sites centered in cell group A8. Tracer deposits in cell group A10 also elicited a preferential labeling of the extrastriosomal matrix, but this innervation was sparse compared to the prominent labeling of fibers in the ventral striatum. An almost exclusive innervation of caudal and ventral striosomes of the head of the caudate nucleus occurred after a deposit of tracer in the pars lateralis of the substantia nigra. Mixed labeling of striosomes and matrix occurred with injection sites centered in the rostral, cell-sparse part of the pars compacta of the substantia nigra. Clusters of tyrosine hydroxylase-immunoreactive neurons within this zone, most likely representing finger-like extensions of the caudal densocellular zone of the pars compacta, might have accounted for part of the striosomal labeling in these cases. We conclude that different subdivisions of the A8-A9-A10 dopamine-containing cell complex of the cat's mesencephalon project preferentially to striosomes or to extrastriosomal matrix. On this basis we suggest that there may be different functional channels in the mesostriatal projection, including, from cell group A8, a channel providing dopaminergic modulation of sensorimotor processing in the striatal matrix, and, from the densocellular zone of the substantia nigra pars compacta, a channel leading to limbic-related mechanisms represented in the striosomal system.

Topographical organization of the afferent connections of the principal ventromedial thalamic nucleus in the cat.

The afferent connections to the principal division of the ventromedial thalamic nucleus (VMP) were studied in the cat by means of the HRP retrograde transport technique. The large (40 nl) and small (20 nl) injections of this enzyme were delivered into the VMP using different stereotaxic approaches. The main afferents to VMP emanated bilaterally from the prefrontal, premotor, and rostral agranular insular cortices. Another important group of afferents to the VMP were those originating in the rostral third of the reticular thalamic nucleus, the entopeduncular nucleus, the substantia nigra pars reticulata, and the deep cerebellar nuclei. From the cerebellar nuclei, the contralateral lateral nucleus and the caudal third of both (ipsi and contralateral) medial cerebellar nuclei were the origin of afferents to the VMP. Other cortical areas projecting (in a lower density) to the VMP were the motor cortex, the cortex along the anterior ectosylvian sulcus, the granular insular cortex, the posterior agranular insular area, the prelimbic area, and the cortex along the posterior rhinal sulcus (SRP). Among other subcortical prosencephalic structures projecting to the VMP are the dorsal claustrum, substantia innominata, hypothalamic formations, and the zona incerta. Projections originated from the brainstem in the lateral part of the intermediate and deep layers of the superior colliculus, the central gray matter, the locus coeruleus, and the reticular formation. The nucleus tegmenti pedunculopontinus pars compacta, parabrachial nuclei, the vestibular complex, and the spinal trigeminal nucleus were also origins of projections to the VMP. We conclude by emphasizing the important bilateral cortical modulation of the different functions attributed to the VMP: recruiting-response mediation, reticular-activating system participation, and extrapyramidal motor integration. In light of the connections just described, the VMP may be considered as a point for impulses coming from complex association cortical areas and limbic formations to converge with those emanating from cortical and subcortical motor structures.