No abstract

For about 20 months the development of hand preferences in 21 experimentally naive common marmosets (Callithrix jacchus ) was examined in 15 different tests. Test preferences were compared with their spontaneous behavior preferences in such contexts as feeding, grooming, play, and others. In the spontaneous use of the hands, only eight animals showed a significant lateral preference ( 2 left-handed, 6 right-handed). During the test period, however, the number of handed marmosets increased to 19 ( 5 left-handed, 14 righthanded). Most of the animals fluctuated considerably in their preference levels, a situation which led to a remarkable test response inconsistency of handedness. When the test situation was changed, complete reversals of handedness were more frequent than weakening or strengthening of a particular preference. The animals' emotions during the test session and environmental variables affected handedness significantly. None of the tested marmosets showed an increase of hand preference from the first to the last test. Our results indicate that Callithrix is ambidextrous rather than handed

The primary visual cortex of Callithrix jacchus occupies a large portion of the occipital neocortex and can be safely delineated from fetal stages onwards. In 20 animals ranging in age from fetal to adult age the morphological development of area 17 was evaluated and compared with the growth of whole brain, skull, and head size. Cortical thickness, surface area, and volume of the area were determined in addition to predominant growth directions. The volume of area 17 approximately doubles between birth (241 mm3) and three months of age (506 mm3). This maximum value marks an overshoot in growth (volume: 180%, surface area: 150%, thickness: 122%), which is followed by a considerable reduction before adult values (100%) are reached. Although these values seem to indicate that the overall reduction in size is fairly isometric, growth and regression are locally anisometric. For example, layers II-IVc contribute disproportionately to the overshoot; thickening is less pronounced than tangential growth and follows a slightly different time course. These data suggest that the developing visual cortex represents a highly dynamic distribution space for the developing synaptic junctions which should be taken into account in studies on synaptogenesis. By comparison it is suggested that this growth dynamic is not restricted to area 17 but also occurs in some other parts of the cerebral cortex. In contrast, most subcortical brain regions apparently do not undergo overshoot growth. Structural changes of the skull compensate the overshoot in cortex growth, so that head size increases steadily.

Purpose Preoperative chemoradiotherapy (CRT) is supposed not only to reduce lymph node metastases but also lymph node recovery in rectal cancer specimens. The objective of this prospective study was to determine the effects of chemoradiation on mesorectal lymph node retrieval under terms of a meticulous histopathological evaluation. Methods Specimens from 64 consecutive patients with stage II/III rectal cancer receiving preoperative 5-FU-based CRT were investigated. All patients were treated within the German Rectal Cancer Trial CAO/ARO/AIO-04. After surgery (including quality assessed total mesorectal excision), extensive pathological diagnostics was performed with embedding and microscopic evaluation of the whole mesorectal soft tissue compartment. Results A total number of 2,021 lymph nodes were recovered (31.6 per specimen) within pathological work-up. There was no significant correlation between the number of retrieved nodes and patient-as well as tumor-dependent parameters. Lymph node size constantly amounted for less than 0.5 cm. Twenty patients (31.3%) had persistent nodal metastases. A considerable incidence of residual micrometastatic involvement in lymph nodes <0.3 cm (in 9.4% of all patients) was detected by extensive pathologic work-up. Conclusion Reliable nodal staging with high numbers of detected nodes was feasible after neoadjuvant CRT. Micrometastases frequently occur in small lymph nodes detected by microscopic evaluation.

SummaryIn a retrospective study sex ratio and mortality were analysed in a captive colony of common marmosets (Callithrix jacchus). Seven hundred and thirty-five infants in 294 litters (20 singletons, 119 twins, 140 triplets, 14 quadruplets) out of 57 breeding females were evaluated. The sex ratio at birth was O· 95 males: 1· 0 females. The frequency of males and females, as well as the sex composition of twins and triplets confirm the assumption of dizygotic twinning in the common marmoset. According to age at death, 9 categories were differentiated, with perinatal mortality being the highest. Once early infancy had passed the probability of a common marmoset infant of our colony reaching childhood is nearly 95070. Sixty per cent of all liveborn infants survived beyond 18 months. Morta1ity of infants at birth from primiparous mothers did not differ from that of pluriparous females, nor did the survival rate of infants with the filial generation the respective female had reached (F1 to F 6 ). Females with a high ratio of triplets and quadruplets had a lower reproductive success than females with a majority of singleton or twin deliveries. Differential mortality between males and females was not observed. The frequency of stillbirths was not strongly related to parity, but was to litter-size. Most stillborn babies were seen· in sets of quadruplets, most abortions in singletons. A normal socialization in a stable social environment, as well as not pairing the animals before they are fully adult, are considered important factors in good breeding success and infant survival.