Charles W. Bodemer

Localization of newly synthesized proteins in regenerating newt limbs as determined by radioautographic localization of injected methionine-S35

Abstract Sites of amino acid incorporation within the regenerating forelimb of adult Triturus viridescens were determined by the radioautographic localization of injected methionine-S 35 . The limb regenerates studied ranged in age from 24 hours to 27 days. During the first few days after amputation the epidermis only produces an intense radioautographic reaction. The intensity of the reaction of the mesodermal tissues increases by the fifth day, when the periosteum of the transected humerus and the terminal portions of the cut muscles and nerves display a concentration of radioactivity. Fragments of sarcoplasm detached from the damaged muscles produce a strong reaction, suggesting that they are not moribund fragments. Those osteocytes apparently being released from the degenerating bone are highly radioactive. The intensity of the radioautographic reaction is generally even throughout the blastema during the growth phase. The radioautographs suggest that during the growth phase the peripheral nerve may exert an influence on protein synthesis within the undifferentiated blastemal cell. In later stages the more intense reduction of emulsion is produced by those cells undergoing differentation. The observations thus suggest that increased incorporation of amino acid is characteristic of the regenerate generally, and comprises a significant feature of dedifferentiating as well as differentiating cells.

Cortical localization patterns in the somatic sensory cortex of the opossum

Abstract Primary evoked responses and single neuron activity were recorded from the cerebral cortex of the virginian opossum following stimulation of the appendages, particularly a contralateral forepaw and its digits. The electrical activity and discharge patterns of single neurons were comparable to those in higher mammals; both inhibitory and occlusive interactions were observed. Primary evoked responses also resembled those in higher mammals. The areas of the cerebral cortex which responded to stimulation of the palm and the five digits were coextensive, comprising about one-third of the dorsal surface of the cerebral hemisphere. Topographic maps for the contralateral palm and digits constructed on the bases of peak-to-peak voltage and latency of primary evoked response differed in both location and arrangement. Latency-based maps were more medially displaced than amplitude-based maps obtained from the same data although these were usually a mirror image of the amplitude maps. Two possible explanations of this differing topographic arrangement are tendered, and it is suggested that the cortical map based upon minimal latency of the primary evoked response is the primary representation of the periphery at the cerebral cortex.

The microscope in early embryological investigation.

The microscope became an instrument of scientific investigation during the 17th century, its application leading to the discovery of the spermatozoa and profound changes in embryological thought. The

Concepts of reproduction and its regulation in the history of western civilization

Abstract Concepts of reproduction and its limitation have varied considerably in western history. Ancient ideas and practices progressed from a magico-religious form to one of more rational and empirical nature, but they remained relatively crude and incomplete. The dominant attitudes of the medieval period discouraged progress in the understanding of reproduction and attempts at its control. As the secularization of western society and scientific inquiry gained momentum during the modern period, knowledge of reproduction increased, and by the end of the nineteenth century investigators had arrived at an understanding of the first processes of embryonic development. This knowledge was not, however, soon applied to the control of reproduction. The latter, expressed in contemporary attitudes and practices, required more adequate understanding of female reproductive physiology and the acceptance of the principle of conception control at the societal level.

France, the fundament, and the rise of surgery

This article describes events in 17th and 18th century France that resulted in the elevation of surgery from a lowly status to one of parity with medicine. Changes in the education and organization of surgeons are described, and the nature and significance of the successful operation for fistula-in-ano on Louis XIV is considered in some detail.