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The differentiation of the gallbladder mucous membrane in chick embryos has been studied from the 11th day of incubation until hatching (stages 37-46 of Hamburger an Hamilton 1951) with scanning electron microscope. The surface of the mucous membrane, at the 11th day of incubation, appears regularly smooth. From the 12th day onwards, longitudinal folds appear on the surface of the mucous membrane, becoming more and more numerous and complicated in the following days. During the last days of incubation, branching and anastomosing folds are present. At the 11th day of incubation, the epithelial cells lining the gallbladder surface have flattened apices, with short microvilli. From the 12th day onwards, the epithelial cells show dome shaped apices, with long numerous microvilli. From the 15th day of incubation onwards, some particular secretory cells can be detected. The appearance of these cells is probably related to the water-absorbing function of the gallbladder which in the last days of incubation completes its functional development, because of precise digestive requirements of the chick embryo.

The morphology of the retinal photoreceptors of the butterfly fish Pantodon buchholzi has been studied by electron microscopy in both light- and dark-adaptation. The photoreceptors in this species are readily divisible into rods and cones based on morphological criteria. No double or twin cones are present. The rod photoreceptors show marked retinomotor movements. In light-adaptation they are extremely elongate cells while in the dark-adapted state they are much shorter. Cones seem to respond but minimally to the circadian cycle. Rod outer segments are composed of membranous discs of uniform diameter displaying several incisures. The inner segment has a small distal ellipsoid and a thin myoid region which is lost in dark-adaptation. The nuclei of rods are condensed and always located vitread to the external limiting membrane. The rod synaptic spherule displays 2 or 3 invaginated sites. The single cones display a tapering outer segment. The wider inner segment contains a large electron-dense ellipsoid with small glycogen deposits located peripherally. The cone nuclei are large and vesicular and usually located sclerad to the external limiting membrane. The synaptic pedicle of cones is larger and more electron-lucent and contains more synaptic sites than do the rods. No mosaic pattern of arrangement of the photoreceptors is apparent. Except for the obvious lengthening or shortening of the rods, the morphology of the photoreceptors changes but little during the circadian cycle.

Muscle biopsies of the mandible adductors of the Wistar rat (Rattus norvegicus Berkenhout) have been analyzed enzyme-histochemically for the investigation of the postnatal development (42.-126. d post partum) of their muscle fibers with special regards to the fiber types. The following methods have been used in this investigation: myofibrillar adenosine triphosphatase (ATP-ase) with different pre-incubations, Sudan black B (triglycerides), periodic acid-Schiff reagent (PAS) (glycogen), Gomori modified Trichrome staining. Quantitative analysis of muscle fibre-type composition and muscle fibre size was done from different regions of muscle sections. Estimation of the fiber size was carried out by measuring the minimum diameter of each type of muscle fibre.

The ultrastructural study of macrophages of germinal centers in the secondary lymphoid follicles of the rat spleen and mesenteric lymph nodes was performed. It was demonstrated that besides macrophages containing necrotic lymphocytes and plasma cells in various stages of degradation (which are already well described in the literature) the germinal centers are also populated with macrophages displaying specific ultrastructural features which enable their precise identification. These cells contain numerous vacuolar inclusions of different size, filled with electron lucent, flocculent material. The dense bodies and membrane profiles are also present in varying amount within the vacuolar content. The dense bodies contain polysaccharides which are detected by the thiocarbohydrazide-silver proteinate method. Very rarely, these cells contain the phagocytosed cellular debris, which is readily distinguished from the cytoplasmic inclusions.

The need for closer and personal scientific exchange among anatomists, histologists, embryologists, morphologists, anthropologists, veterinarians, dentists, biologists, and zoologists, and professionals of allied health sciences, and their interest in the uniformity of the technological language they all used in teaching and research, led a group of leaders in the field of Anatomy to found the International Federation of Associations of Anatomists (IFAA).

Development of the rabbit spinal cord leptomeninges was examined in embryos and fetuses aged 12 to 30 d post-conception. In the early stages of development all mesenchymal cells surrounding the neural tube were structurally similar, resembling immature fibroblasts. At 16 d post-conception cells adjacent to the glia limitans showed little structural change, apart from an increase in the amount of rough endoplasmic reticulum, but cells in the presumptive arachnoid became packed with glycogen. By E22 glycogen was present in pial cells but never in the amounts found in the arachnoid. As development proceeded the amount of glycogen in the leptomeninges declined. Pial collagen increased both in amount and in fibre diameter with age.

The prenatal development of the human Brunner's glands has been investigated in 23 fetuses from the 10th week of gestation to full-term. At 12 weeks, a few cords of epithelial cells were seen budding from the duodenal mucosa immediately beyond the pyloric sphincter. They represent the initial stage of the development of Brunner's glands. At 16 weeks, Brunner's glands originated as simple tubular downgrowths from the bottoms of the most proximal crypts of the duodenum. The secretory products of the component cells of these primitive tubules contained periodic acid schiff (PAS) positive material which was largely supranuclear in position and resisted digestion by diastase. From 20 weeks to full term, the Brunner's glands developed in a progressive fashion starting in the proximal part of the duodenum near the pyloroduodenal junction. Further tubular downgrowths were added distally, leading to an increase in length of the glandular tissue. The gland showed an increase in size proximally due to elongation and branching of the tubules. At birth, the glandular cells of Brunner's glands resembled those of normal adult in structure and staining reactions. The PAS staining of the cells of the early developed glands (at 12 weeks) was as intense as those of the full-term. The secretory materials of the developed Brunner's glands showed negative reaction with Alcian blue (AB) at pH 2.5 at any stage of development. These results suggest that the mucin secreted by the developed Brunner's glands of human is neutral mucopolysaccharide in nature.

The length and termination of the circumflex branch of the left coronary artery were studied in 81 hearts, after injection of the coloured substance containing a radiopaque medium. The hearts were radiographed, dissected, drawn and photographed. The short type of circumflex branch, defined as a branch that did not reach the crux cordis, was found to be much more frequent (86.4%) than the long type and terminated in the majority of the cases (76.5%) as one of the posterior branches of the left ventricle.

The current understanding of the kidney development in the pelvis and then a subsequent migration to the lumbar region is disputed. A total of 96 embryos were examined after they were obtained from 24 pregnant rats. A group of 4 pregnant rats were sacrificed at each day over the period from 12 to 17 successive days of pregnancy. An almost equal number of embryos were histologically investigated at each day using the paraffin technique. This was fulfilled by taking serial sections throughout the entire length of the trunk. The 13 days old embryo presented the appearance of the definitive kidney as indicated by the microscopical display of the ureteric bud invading the nephrogenic cord. This microscopic event took place at the lower lumbar region of all examined embryos. Therefore, the present work gives a microscopic evidence that the definitive kidney develops in the lumbar region.

The possibilities of extraction and transplantation of bone with microsurgical vascular anastomosis for reconstruction of mandibular defects were to be examined in animal experiments. On the basis of the arterial vascularization of the ossa coxae of the Göttingen minipig which has been demonstrated, the cranioventral region of the os ilium is especially suitable as transplant. The separate vascularization of this bone area allows the extraction of a bone block with a sufficiently long afferent vascular stump. The experimental operations performed in the meantime display an excellent rate of healing of the microsurgically anastomosed bone transplants in the mandible.