The teaching of human Anatomy in Spain at the beginning of the twenty-first century

This work, which merely aims to reflect theauthors’ opinions, begins by pointing out a seriesof problems involved in the teaching of HumanAnatomy in Spanish Universities over the pastquarter century. Emphasis is placed on both thecauses that can be attributed to anatomists themselvesand on those deriving from Universitylegislation, especially after the University ReformLaw. We also refer to the small body of literaturepublished by Spanish anatomists with respectto the teaching of Anatomy, cadaver dissection orthe use of new technologies in such teaching. Wethen offer an overview of the current circumstancesand future possibilities not only of teachingand methodology but also as regards instructorsand departments. We offer a reference tothe Spanish Anatomical Society and we end byproposing a series of guidelines for the immediatefuture with a view to optimising the teachingof Human Anatomy and Embryology andthe professionalisation of future anatomists

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Magnetic resonance microscopy versus light microscopy in human embryology teaching.

A study was carried out on the application of magnetic resonance microscopy (MRM) in teaching prenatal human development. Human embryos measuring 8 mm, 15 mm, 18.5 mm, and 22 mm were fixed in a 4% paraformaldehyde solution and sections obtained with magnetic resonance imaging (MRI) were compared to those prepared for light microscopy (LM), using the same embryos. The MRM and LM slices were of a similar quality. In the MRM sections, embryonic organs and systems were clearly visible, particularly the peripheral and central nervous systems, and the cardiovascular and digestive systems. The digitalization and clarity of the MRM images make them an ideal teaching aid that is suitable for students during the first years of a health-science degree, particularly medicine. As well as providing students with their first experience of MRM, these images allow students to access, at any time, all embryos used, to assess changes in the positions of different organs throughout their stages of development, and to acquire spatial vision, an absolute requirement in the study of human anatomy. We recommend that this technique be incorporated into the wealth of standard embryonic teaching methods already in use.

The human embryo development through MMR.

This study evaluates the use of the Microscopic Magnetic Resonance (MMR) in the human prenatal development. Human embryos (8mm, 15mm, 18mm and 22mm in length) fixed in 4% paraformaldehyde were used. Results were compared with light microscopy (LM) images. The internal configuration of the embryos can be clearly observed as well as many organs such as liver, lungs, heart, including their spatial relationships. In general MMR sections are less clear and show minor details than those by LM. Neverthless, many advantages are provided by using this technique. For example it is possible: a) to make three-dimensional (3-D) surface and internal full or partial reconstructions; b) to evaluate the presence of developmental anomalies; c) to evaluate the tissular preservation degree of the specimens; and d) to apply morphometric techniques to unfixed specimens. In our opinion the advantages derived by using MMR are many and overcome the disadvantages. This study demonstrates that MMR can be incorporated into ordinary laboratory techniques in human development studies, being also an initial election technique opposite to others more aggressive.

Immunocytochemical study on the triple origin of the sphincter iris in the chick embryo.

The ontogenic development of the sphincter iris has been studied by immunocytochemistry and standard staining on chick embryos from stage 25 HH to the time of hatching. We have used the monoclonal antibody 13F4, a highly specific marker of muscular cells. We have observed three different regions in the iris. In the pupillary region, immunoreactive cells are in continuous contact with the inner epithelium of the pupillary margin. In the intermediate region, the outer epithelium forms buds of pigmented cells that emigrate toward the stroma. In this epithelium cells that are totally or partially unpigmented exist, and they are 13F4 positive. In the sphincter we have observed 13F4 positive cells with melanin granules. In the ciliary region, the immunoreactivity appears in dispersed mesenchymal cells. The present findings are consistent with a triple origin of the sphincter iris in the chick embryo. This muscle is derived from the inner epithelium of the pupillary margin, the intermediate region of the outer epithelium, and from the mesenchymal cells. The cells of the inner epithelium of the pupillary margin are differentiated into smooth muscle cells, and the remaining cells form striated muscle cells.

Anomalias cardíacas producidas por disminución de flujo sanguíneo en embriones de pollo / Cardiac produced by disminution of the blood flow in chicken embryos

En un intento por conocer experimentalmente la importancia de los factores hemodinámicos en la morfogénesis cardíaca, diseñamos una investigación para determinar las consencuencias que ejerce la disminución del flujo sanguíneo en el desarrollo del corazón en embriones de pollo. A tal objeto, los embriones fueron intervenidos durante el estadío 16, mediante la ligadura de la vena vitelina derecha en unos casos, e izquierda en otros, observando sus efectos en embriones de los estadíos 36 y 37 mediante técnicas ultraestructurales de barrido. Nuestros resultados indican que la disminución del volumen sanguíneo causa alteraciones en la morfogénesis cardíaca

Lectin-binding patterns in the development of the cerebellum.

We studied the binding distribution of several lectins, Con A, DBA, UEA and WGA, in the embryonic development of the chick cerebellum between stages 18 to 45 of Hamburger and Hamilton. We observed a differential labeling (in intensity and distribution) in the migratory and cortical layers of the cerebellum anlage with these different lectins. The different distributions and modifications in the labeling pattern suggest intense variations of the glycoproteins and glycosaminoglycans in the extracellular matrix during development. These variations coincide with cellular and organizational phenomena in the migratory and cortical layers, and suggest compartmentalization of the Purkinje cell labeling.

The ontogeny of the cerebellar fissures in the chick embryo.

We have studied the chronology of appearance and the cortical changes which precede the fissures appearing between stages 34 to 40. In this paper we demonstrate the structural modifications of the cerebellar cortex defined as the anlagen of the fissures. The anlage of a fissure begins in a well-determined place of the cerebellar cortex. It begins with a thickening of the internal cortical cell layer, which finally folds. These modifications precede other similar ones which occur in the overlying external granular layer. On the other hand, these cortical structural modifications precede the transversal projection of the fissures. Chronological order of appearance of the anlagen of the fissures, related to the appearance of fissures on the surface of the cerebellum is also given.

[Morphogenesis of the tubo-uterine junction in the human fetus]. / Morphogenèse de la jonction tubo-utérine chez le foetus humain.

The utero-tubal junction morphology has been analysed by means of the uterus and tubes study of 37 human foetuses and new-born infants between the 15th gestational week and the 3rd life week. Being difficult to identify it before the 20th gestational week, it is possible to recognize the uterotubal junction by the muscular fibers traject, as well as by the arrangement of the reticuline fibers and mesenchymal cells of the submucosa. During the previously reported period we haven't observed any sphincterian structure at the utero-tubal junction level; thus, we believe that the closure mechanism is purely functional one.

The formation, septation and fate of the truncus arteriosus in man.

The results of our studies enable us to draw the following conclusions. The truncus appears in the human embryo, between Stages XII and XIII, as a portion of the aortic sac which invaginates into the interior of the pericardial cavity. Therefore it is an arterial portion which is added to the heart. It lengthens progressively. The sigmoid valves form in the angle between the bulbus cordis and the truncus. Septation of the truncus begins when the sixth arterial arches appear in embryos of 6 to 8 mm. The process is very rapid; commencing in embryos of 6 to 7 mm, it is complete in embryos of 10 to 11 mm, that is to say, during only five days. The septation mechanism is extrinsic. The peribranchial mesenchyma which accompanies the aortic sac in its invagination advances principally on the right inferior part and insinuates itself between the fourth and sixth arterial arches, separating the truncus pulmonalis from a portion of the ascending aorta. An aorticopulmonary communication exists for a certain period prior to fusion of the two blocks of mesenchyma; there is a mesenchymal island. On the contrary, in the bulbus cordis septation is effected by the bulbar ridges. Septation of the truncus, which does not exist in the primitive cardiac tube, occurs prior to that of the bulbus cordis. While septation of the truncus has been already completed in embryos of 10 mm, septation of the bulbus cordis is completed only in embryos of 14 to 16 mm. Therefore the bulbus and the truncus are two portions, different in respect of both structure and septation. There is no continuity between the bulbar ridges and the septation of the truncus. They are separated by the sigmoid valves. This makes it possible to observe independent malformations in the bulbus and in the truncus. In the truncus the mesenchyma passes between the two vessels. They do not have a common septum, and it is for this reason that the surgeon can separate them in the mature heart.

Malformation of the venous sinus in human embryos.

2 human embryos of stages XV and XVII are studied, in which the persistence of the left vitelline vein opening into the venous sinus (sinus venosi cordis) is described.

The morphogenesis of the ventricular flow pathways in man.

This work which is based on the study of eight human embryos of 4,5 to 13,6 mm from the Madrid collection, and also on six plastic reconstructions made by the BORN method, and on experiments on chick embryos (ligature of the left vitelline vein in embryos, 3 days of incubation) enables us to reach the following conclusions: no true rotatiorial movements take place during normogensis. Only ventromedial rotation of the right ventricle is observed in stages 12 to 14. This rotation will place the right ventricle, and therefore the vestibulum pulmonalis in front of the aortic infundibulum. We consider that the initiation of cardiac septation is to a great extent due to hemodynamic. causes. During normogenesis in all cases, from the earliest stages of development the presumptive pulmonary outflow tract is always anterior and to the right of the presumptive aortic tract. We do not agree with the statement of GOOR and EDWARDS and VAN PRAAGH R. and VAN PRAAGH S. (1965), that in some stages the presumptive coni of the aorta and pulmonalis are arranged inversely to the way in which they will arranged later.

Innervation of the sinu-atrial node and neighbouring regions in two human embryos.

In human embryos of 20 to 23 mm (36 to 40 days) it is possible to identify on the right side a nerve that we may call the sinusal, which originates by several roots from the nervus vagus dexter (Figs. 1A, B, D), descending through the right ventrolateral face of the primary trachea and right bronchus (Fig. 2, arrows). Beaded in appearance, it gives a fine anastomotic branch which, passing in front of the arteria pulmonalis dextra, passes to the left side (Figs. 2B, C, D; AN). At this level it gives the large branch for the nodus sinoatrialis which, penetrating through the wall of the superior vena cava, provides a rich innervation for the nodus sinoatrialis which is already in an advanced stage of differentiation (Fig. 3, 2; Cy, D, AN). Afterwards it gives fine branches which, following the atrial fold, are distributed throughout the posterior face of the atrium dextrum (Fig. 3). It increases in diameter and, passing through the angle formed by the right pulmonary veins with the atrium dextrum, reaches the intrapericardial portion of the inferior vena cava in the vicinity of its outlet from the atrium (Fig. 3, arrows). The whole innervation is parasympathetic at the stages studied.