Parathyroid autotransplantation was first described in 1907 by Halsted. However, this simple and effective method of preserving parathyroid function has been used with increasing frequency only during the past 25 years. Beginning in the late 1960s, our group has transplanted normal parathyroid tissue into the ipsilateral sternocleidomastoid muscle whenever these glands could not be preserved in situ with adequate blood supply. In addition, if the blood supply of all four parathyroid glands appeared compromised, cryopreservation of parathyroid tissue was performed in case the autotransplanted tissue did not function after surgery. Since 1970, 393 patients underwent a total thyroidectomy. Parathyroid glands that could not be saved in situ were biopsied to confirm their identity by frozen section and then autotransplanted. Of the 393 patients who underwent a total thyroidectomy, 261 patients required transplantation of one or more glands. Among those 261 patients who underwent selective parathyroid autotransplantation, 33 (13%) required temporary calcium and vitamin D supplementation. Of these 33 patients, 2 (less than 1%) had permanent hypoparathyroidism and are receiving long-term vitamin D therapy.

(SURGERY 7989; From the

The purpose of the work was to develop an in vitro model for the study of lymphatic endothelium and to determine, using this model, whether or not a cytoplasmic process may be involved in transendothelial transport . Segments of canine renal hilar lymphatics were dissected clean, cannulated at both ends, and transferred to a perfusion chamber for measurement of transendothelial protein transport and for ultrastructural tracer studies . The segments were subsequently processed for light and electron microscopy. By both structural and functional criteria the lymphatics were judged to have retained their integrity. At 37°C, 36 lymphatics showed a mean rate of protein transport of 3 .51 ± 0 .45 (SEM) ug/min per cm' of lymphatic endothelium . The rate was influenced by the temperature of the system, being significantly reduced by 49% ± 4.8, 31% ± 5.3, and 29% ± 3 .9 when the temperature was lowered to 4°, 24°, and 30°C, respectively . When the temperature was raised to 40°C, the rate was significantly increased by 48% ± 12.2. The vesicular system and the intercellular regions in vessels with increased or reduced rates of transport were analyzed quantitatively to ascertain whether the rate changes could be correlated with ultrastructurally demonstrable changes in either of these postulated pathways . No significant changes in junctional or vesicular parameters were found between the control lymphatics and those perfused at 24°, 30°, and 40°C . At 4°C, the temperature at which the rate of protein transport was maximally reduced, vesicular size decreased, and the number of free cytoplasmic vesicles increased, whereas the number associated with the abluminal and luminal surfaces decreased . We concluded that isolated perfused lymphatic segments transport protein at a relatively constant rate under control conditions, and that this transendothelial transport comprises both temperaturedependent and temperature-independent mechanisms . The findings were considered in terms of the different theories of lymph formation and were interpreted as providing support for the vesicular theory .Lymph, by definition, is formed from that component of the interstitial fluid that moves across the endothelium of lymphatic vessels. However, the pathways taken and the forces that control this fluid movement are poorly understood and therefore have become the subjects of considerable controversy. According to one theory the major pathway lies between adjacent endothelial cells (11,20,21), and hydrostatic (16) or osmotic pressure (11, 12) provides the necessary force for fluid transport. Integral to this theory are the cyclic changes that occur because lymphatic vessels are alternately compressed and then relaxed within the tissues. For instance, if hydrostatic pressure is the major force, intraluminal pressure THE JOURNAL OF CELL BIOLOGY -VOLUME 98 FEBRUARY 1984 629-640 0 The Rockefeller University Press -0021-9525/84/02/0629/12 $1 .00 must be greater than atmospheric attimes, thus causing lymph to flow downstream, and less than atmo...

No abstract

Rat, hamster, and rabbit renal cortical lymphatics were examined by light and electron microscopy. Rat and hamster kidneys possessed both intra- and interlobular lymphatics that were structurally similar at the light microscopic level. Ultrastructural examination of the hamster lymphatic endothelium, however, revealed an unusual arrangement of cytoplasmic extensions not seen in the other two species. The intralobular lymphatics were related primarily to tubules, afferent arterioles, and renal corpuscles and were consistent with lymph formation from both plasma filtrate and tubular reabsorbate. Interlobular lymphatics were seen in connective tissue associated with the interlobular blood vessels. Rabbit cortex contained only interlobular lymphatics. Cross-sectional area, maximum diameter, volume density, and profile density were determined by stereological measurements using a computer-based image analyzer. The morphological data from the rat were used, in combination with published values for lymph flow, to calculate the rate of lymph formation per unit area of endothelium in lymphatics of the renal cortex. Among kidneys fixed by retrograde perfusion, the cortical lymphatic system was most extensive in maximum diameter, volume density, and profile density. It was smallest in the rabbit and intermediate in the rat. Lower volume and profile density were found for rat kidneys fixed by the dripping technique. It was concluded that: tubular reabsorbate probably contributes to renal lymph in the rat and hamster, but not in the rabbit; significant differences exist in the extent of the renal lymphatic systems among the three species, with the hamster kidney having the richest network and the rabbit the poorest; the method of fixation influences the measured size and density of renal cortical lymphatics; and the estimated rate of lymph formation in the kidney of the rat is roughly comparable to that in the dog.