Achromatic synesthesias - a functional magnetic resonance imaging study.

Grapheme-color synesthetes experience consistent, automatic and idiosyncratic colors associated with specific letters and numbers. Frequently, these specific associations exhibit achromatic synesthetic qualities (e.g. white, black or gray). In this study, we have investigated for the first time the neural basis of achromatic synesthesias, their relationship to chromatic synesthesias and the achromatic congruency effect in order to understand not only synesthetic color but also other components of the synesthetic experience. To achieve this aim, functional magnetic resonance imaging experiments were performed in a group of associator grapheme-color synesthetes and matched controls who were stimulated with real chromatic and achromatic stimuli (Mondrians), and with letters and numbers that elicited different types of grapheme-color synesthesias (i.e. chromatic and achromatic inducers which elicited chromatic but also achromatic synesthesias, as well as congruent and incongruent ones). The information derived from the analysis of Mondrians and chromatic/achromatic synesthesias suggests that real and synesthetic colors/achromaticity do not fully share neural mechanisms. The whole-brain analysis of BOLD signals in response to the complete set of synesthetic inducers revealed that the functional peculiarities of the synesthetic brain are distributed, and reflect different components of the synesthetic experience: a perceptual component, an (attentional) feature binding component, and an emotional component. Additionally, the inclusion of achromatic experiences has provided new evidence in favor of the emotional binding theory, a line of interpretation which constitutes a bridge between grapheme-color synesthesia and other developmental modalities of the phenomenon.

Expression of TGF-betas in the embryonic nervous system: analysis of interbalance between isoforms.

Transforming growth factor-beta (TGF-beta) is a family of growth factors with essential and multiple roles during embryonic development. In mammals, three isoforms (TGF-beta1, TGF-beta2, TGF-beta3) have been described. In the nervous system, the presence of TGF-beta1 has remained undetectable in other structures than meninges and choroids plexus, while TGF-beta2 and TGF-beta3 were considered as the neural members of the family. In the present study, we have analysed the expression pattern of the three isoforms in the neural tube, brain, and spinal cord during development in both mouse and chicken. The data reveal specific patterns for each isoform. This work also shows that both TGF-beta1 and TGF-beta3 are expressed in neural crest cells. In addition, we demonstrate the existence of interbalance between TGF-beta1 and TGF-beta3 with possible functional implications, which, together with the expression of TGF-beta1 in the CNS, represents one of the most important contributions of this work.

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.

Dynamic restricted expression of the chaperone Hsc70 in early chick development.

The non-inducible chaperone heat shock cognate 70 kDa (Hsc70) is regulated during development. We now characterize its dynamic expression pattern from gastrulation to early organogenesis. Throughout this developmental period, hsc70 transcripts were largely restricted to neuroectoderm- and mesoderm-derived structures. In stage 10 embryos, Hsc70 protein was expressed in the neural tube with increasing rostrocaudal and decreasing dorsoventral gradients, and in some somite cells. This highly regulated expression of Hsc70 is likely to reflect specific developmental functions, besides its well-characterized role in protein folding.

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.

A monoclonal antibody specific for avian early myogenic cells and differentiated muscle.

A monoclonal antibody raised in mouse in response to homogenates of Remark ganglia and dorsal mesentery of chicken embryos was found to exhibit a unique reactivity towards myogenic cells, heart, striated muscles, and smooth muscles in chicken and quail. Indirect immunofluorescence assays were performed at different stages of chicken and quail embryonic development and, after hatching, on tissue sections and cultured cells. They revealed that the cytoplasmic marker recognized by 13F4 is expressed in early embryonic heart, in somitic myotome (from stage 14 onward), in the skeletal muscles in limbs and trunk, in all muscles in the head and the branchial arches, in the smooth muscles of the digestive tract and blood vessels. In myofibrils of striated muscles, the antigen is localized in the Z lines. The antigenicity of the molecule recognized by 13F4 is not associated with a glycolipid or a glycoprotein. It is of peptidic nature and its molecular weight is 54 kDa. We stress the value of this cell-type-specific marker in studies on ontogenesis and differentiation of all muscular structures, namely, of myocardium and striated muscles, which express 13F4 antigenicity from an early developmental stage.

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.