Differentiation and positioning of nuclei in eggs of the cecidomyid Heteropeza pygmaea

During the first three cleavage divisions of the egg nuclei a precise sequence of spindle orientation and elongation parallel to the longitudinal axis of the egg is apparently involved in positioning one nucleus among the polar granules at the posterior pole of the egg. The size of this nucleus, and the position at which the egg cleaves when pole cell formation occurs, appear to constitute part of the mechanism which ensures that only one nucleus is included in the first pole cell. Blastoderm formation occurs without a well-defined migration of nuclei to the egg surface. Nuclei are so large in relation to the size of the egg that uniform spacing and distribution of nuclei ensures that a large proportion are situated near the egg surface. Those nuclei which are near the egg surface divide synchronously to form a layer of blastoderm nuclei, while membranous cleavage furrows invaginate from the egg surface between them. Nuclei in the central region of the egg chamber condense to form yolk nuclei before blastoderm nuclei have been separated from the rest of the egg by the completion of the cleavage membranes. Polar granules provide the only evidence of fine-structural differences in different regions of the egg chamber cytoplasm. They are found near the posterior pole of the egg from an early stage of oogenesis. They undergo a specific sequence of structural changes and increase in size as the egg grows. No microtubular or microfibrillar arrays have been found in the egg chamber which might form a cytoskeletal basis for spindle orientation or for the spatial differences which develop during differentiation of the uncleaved egg cytoplasm.     

The ultrastructure of paraganglia associated with the inferior mesenteric ganglia in the guinea-pig

The paraganglia of the inferior mesenteric ganglia in the guinea-pig are composed of small chromaffin cells containing an abundance of granule-containing vesicles. The chromaffin cells are almost completely surrounded by satellite cells. In areas in which satellite cell processes do not intervene, the membranes of adjacent chromaffin cells are closely apposed and often form specialized attachment zones. The paraganglia contain a dense capillary network, the endothelial cells of which are often extremely attenuated and show areas of fenestration. The processes of chromaffin cells approach close to the capillary walls and are often bare of satellite cells covering on the side facing the capillary. Evidence has been obtained for the exocytotic release of the contents of chromaffin cell vesicles into pericapillary spaces. Synapses of cholinergic and noradrenergic axons are seen on the chromaffin cells. The cholinergic axons degenerate when the praganglia are decentralized, but the noradrenergic axons, which appear to arise from the local inferior mesenteric ganglia, remain intact. The results suggest that the paraganglia have an endocrine function.     

Advanced renal cell carcinoma: treatment with xenogeneic immune ribonucleic acid and appropriate surgical resection

Herein we describe the first clinical treatment of renal cell carcinoma in humans with xenogeneic immune ribonucleic acid. Twelve patients with advanced renal cell carcinoma have been treated by appropriate operations to remove tumor bulk followed by specific passive immunotherapy. Xenogeneic specific immune ribonucleic acid was prepared from the spleen of normal sheep that had received 4 weekly injections of a homogenate of renal cell carcinoma. Results indicate that 1) xenogeneic specific immune ribonucleic acid can safely be given to humans without local or systemic toxicity, 2) there is a suggestion of clinical benefit, since only 2 patients have had progression of known metastases during treatment with immune ribonucleic acid and 3) xenogeneic immune ribonucleic acid can enhance the immune response to renal cell carcinoma, as demonstrated by in vitro lymphocytoxicity tests.     

Yersinia enterocolitica infection in a 4-month-old infant associated with infection in household dogs

Colon atresia is a rare cause of intestinal obstruction in the neonate and requires early diagnosis and prompt surgical treatment. It is impossible in the neonate to differentiate colon atresia from other forms of obstruction at the time of initial presentation. The diagnosis is confirmed roentgenographically, including views of the abdomen and contrast barium enema series. Lesions proximal to the splenic flexure are treated with initial resection of the atretic segment and a primary anastomosis. Those lesions distal to the splentic flexure are managed initally with a diverting loop colostomy with subsequent staged resection and anastomosis.     

Influence of high temperature stress of 16-day embryos on subsequent hatchability

Two experiments were conducted to determine the effect of acute heat stress on late-stage chicken embryos. Embryos were incubated at a normal control temperature (37.5 degrees C.) for 16 days and were then subjected to 40.6, 43.3, 46.1 or 48.9 degrees C. for various periods of time in another incubator of the same type. At the end of the stress period all embryos were placed back into the control incubator for the remainder of the incubation period. Exposure of embryos for 24 hours to a temperature of 40.6 degrees C, caused no major detrimental effects on hatchability. Exposure for 6 hours to the temperature of 43.3 degrees C, caused a decrease in hatchability with a severe decline in hatchability occurring after 9 hours of exposure. Exposure to 46.1 degrees C. for 3 hours or 48.9 degrees C for 1 hour killed all embryos. Chicks which hatched following a severe heat stress had a high incidence of clubbed, wiry down and exhibited an unsteady gait.