The majority of studies as to whether gastric and nongastric factors are involved in the ' rotation ' of the human embryonic stomach around its longitudinal axis have been morphological. The aim of this study was to analyse, with morphometric support, the influence on the angular modifications during gastric rotation of the simultaneous changes of the gastric walls and mesenteric growth, and the volumes of organs adjacent to the stomach (right, left and posterior groups). Computer imaging techniques were applied on cross sections of a graded series of 10 human embryos (from Carnegie stage (CS) 11) and 2 fetuses. A clockwise gastric rotation occurred during the embryonic period. The most rapid angular modifications took place from CS 11 to 16, after the rotation became oscillatory with angular changes in clockwise and anticlockwise directions, reaching the highest value at CS 18 (at the supraomental part of the stomach : 54.37m ; at the omental part : 68.03m) ; after this period the angular values tended to stabilise. The predominant growth of the left gastric wall over the right and the changes in the width of the gastric mesentery were the most persistent factors involved in the modifications of the transverse gastric angle during the embryonic period although without relationship to their direction. During the increasing angular phases, clockwise rotation was promoted by the decrease of the volume of any group of organs adjacent to the stomach. When the volume of the left and posterior groups increased simultaneously, clockwise or anticlockwise angular directional change was related to the respective decrease or increase adjacent organ volume to the right. We conclude that the stomach of the human embryo undergoes heterogeneous and multifactorial rotation as a consequence of the overall increase in gastric wall growth to the left and the increase of gastric mobility produced by the previous mesenteric enlargement, and that the rotational direction results from the forces exerted on the stomach and the gastric mesenteries by the adjacent organs.

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Introduction:In general, the evaluation of the university students is carried out some days after the lessons were taught. The aim of our study was to establish how much influence the way of transmitting information and other environmental factors (the number of students and the time) have on the immediate learning.Material and Methods: 66 students on the "Developmental Biology and Teratogeny" course took part in the study. At the end of a theory-practice activity an exam was given based on the matter taught during the session. We were looking for differences in performance based on differences in the teaching method, the type of questions asked, the number of students per session, and the time at which the session was held.Results: Bett er results were obtained for the content that had been taught without audiovisual suppor t; for the questions for which the students had to define concepts and for the questions that they had to answer with words less complex and with less difficult phonetically. Better results were also obtained by the students who did the session in the first afternoon time slot, in comparison with those who did the session later in the afternoon.Conclusions: The methodology that enabled the students to perceive the non-verbal communication

The influence of the teaching methodology on the immediate learning. Introduction: In general, the evaluation of the university students is carried out some days after the lessons were taught. The aim of our study was to establish how much influence the way of transmitting information and other environmental factors (the number of students and the time) have on the immediate learning. Material and Methods: 66 students on the "Developmental Biology and Teratogeny" course took part in the study. At the end of a theory-practice activity an exam was given based on the matter taught during the session. We were looking for differences in performance based on differences in the teaching method, the type of questions asked, the number of students per session, and the time at which the session was held. Results: Bett er results were obtained for the content that had been taught without audiovisual suppor t; for the questions for which the students had to define concepts and for the questions that they had to answer with words less complex and with less difficult phonetically. Better results were also obtained by the students who did the session in the first afternoon time slot, in comparison with those who did the session later in the afternoon. Conclusions: The methodology that enabled the students to perceive the non-verbal communication

In order to analyse the patterns of cellular proliferation both in the mesenchyme of the urorectal septum (URS) and in the adjacent territories (posterior urogenital mesenchyme, anterior intestinal mesenchyme and cloacal folds mesenchyme), as well as their contribution to the process of cloacal division, a computer-assisted method was used to obtain the nuclear area of 3874 mesenchymal cells from camera lucida drawings of nuclear contours of selected sections of human embryos [Carnegie stages (CSs) 13-18]. Based on changes in the size of the nucleus during the cellular cycle, we considered proliferating cells in each territory to be those with a nuclear area over the 75th percentile. The URS showed increasing cell proliferation, with proliferation patterns that coincided closely with cloacal folds mesenchyme, and with less overall proliferation than urogenital and intestinal mesenchymes. Furthermore, at CS 18, we observed the beginning of the rupture in the cloacal membrane; however, no fusion has been demonstrated either between the URS and the cloacal membrane or between the cloacal folds. The results suggest that cloacal division depends on a morphogenetic complex where the URS adjacent territories could determine septal displacement at the time that their mesenchymes could be partially incorporated within the proliferating URS.