The early morphogenesis of the vomeronasal organ of Jacobson is documented in the human embryo and early fetus using light and electron micrographs. Differences between its structure and that of the olfactory epithelium are discussed.

Previous studies have indicated that asexual reproduction (fissioning) in the planarian Dugesia dorotocephala is socially controlled through a cephalic mechanism: Isolation releases fissioning; grouping inhibits it; decapitation, at the level of the auricles, releases it even in grouped subjects. The brain is not necessary for programming the actual events of fissioning; these are orchestrated by the segmental plexus fissioning (SPF) system. Various surgical cuts were made to ablate selected portions of the central nervous system of isolated and grouped planarians in order to ascertain the inhibitory or facilitatory effects of these in the physiological mediation of such control on the SPF system. These results were synthesized into a model of this control system; the anterior lobes and optic regions of the brain inhibit the SPF system, and the anterior and caudal segmental plexuses facilitate it. These influences are partially tonic and partially contingent upon social stimulation.

No abstract

Forty consecutive probable neck abscesses were evaluated prospectively with ultrasonography to determine the necessity and timing of surgical drainage, and the results were correlated with the physical and operative findings. Ultrasonography was found to be superior to physical examination in predicting the presence (or absence) of pus in these cases. Diagnostic ultrasonography has gained wide acceptance in the evaluation of thyroid and recently has been applied to the study of extrathyroidal neck masses. The definition of the quality, extent, and location of a cervical lesion by ultrasonography has, in many cases, supplied the clinician with invaluable data on which to base therapeutic decisions.The evaluation of inflammatory neck masses has always proved to be difficult for the head and neck surgeon. The vital decision of whether to manage these lesions medically or surgically often rests on insensitive and nonspecific roentgenographic studies and on findings from the physical examination. The physical finding of "fluctuance" (the quality of a wavelike motion produced by palpation of a body cavity when it contains fluid) is a relatively specific yet insensitive and often misleading property of the tissue under examination. It is not uncommon to discover pus in an inflammatory cervical mass thought preoperatively to be nonfluctuant.

No abstract