To examine the possible role of microtubule-based transport in testicular function, we used immunofluorescent techniques to study the presence and localization of the microtubule mechanoenzymes cytoplasmic dynein (a slow-growing end-directed motor) and kinesin (a fast-growing end-directed motor) within rat testis. Cytoplasmic dynein immunofluorescence was observed in Sertoli cells during all stages of spermatogenesis, with a peak in apical cytoplasm during stages IX-XIV. Cytoplasmic dynein immunofluorescence was also localized within Sertoli cells to steps 9-14 (stages IX-XIV) germ cell-associated ectoplasmic specializations. In germ cells, cytoplasmic dynein immunofluorescence was observed in manchettes of steps 15-17 (stages I-IV) spermatids, and small, hollow circular structures were seen in the cytoplasm of step 17 and step 18 spermatids during stages V and VI. Kinesin immunofluorescence was observed in manchettes of steps 10-18 spermatids (stages X-VI). The stage-dependent apical Sertoli cell cytoplasmic dynein immunofluorescence, in conjunction with the previously reported orientation of Sertoli cell microtubules (slow-growing ends toward the lumen) and peak secretion of androgen-binding protein and transferrin, is consistent with the hypothesis that cytoplasmic dynein is involved in Sertoli cell protein transport and secretion. Further, the localization of cytoplasmic dynein and kinesin to manchettes is consistent with current hypotheses concerning manchette function.
. Effect of mechanical deformation on structure and function of polymorphonuclear leukocytes. J. Appl. Physiol. 82(5): 1397-1405, 1997.-The present studies were designed to test the hypothesis that mechanical deformation of polymorphonuclear leukocytes (PMN) leads to functional changes that might influence their transit in the pulmonary capillaries. Human leukocytes were passed through 5-or 3-µm-pore polycarbonate filters under controlled conditions. Morphometric analysis showed that the majority of PMN were deformed and that this deformation persisted longer after filtration through 3-µm filters than through 5-µm filters (P , 0.05) but did not result in the cytoskeletal polarization characteristic of migrating cells. Flow cytometric studies of the filtered PMN showed that there was a transient increase in the cytosolic free Ca 21 concentration after both 3-and 5-µm filtration (P , 0.01) with an increase in F-actin content after 3-µm filtration (P , 0.05). Although L-selectin expression on PMN was not changed by either 5-or 3-µm filtration, CD18 and CD11b were increased by 3-µm filtration (P , 0.05). Priming of the PMN with N-formyl-methionyl-leucyl-phenylalanine (0.5 nM) before filtration resulted in an increase of CD11b by both 5 (P , 0.05)-and 3-µm (P , 0.01) filtration. Neither 5-nor 3-µm filtration induced hydrogen peroxide production. We conclude that mechanical deformation of PMN, similar to what occurs in the pulmonary microvessels, induces both structural and functional changes in the cells, which might influence their passage through the pulmonary capillary bed. neutrophils; deformability; F-actin; adhesion molecules THE PULMONARY MICROVESSELS restrict the passage of polymorphonuclear leukocytes (PMN) because of the discrepancy between the size of the PMN and the size of the lung capillary segments (5, 14, 15). Although erythrocytes [red blood cells (RBC)] have similar maximum dimensions to PMN, their greater deformability allows them to negotiate these restrictions more quickly (14). This results in pulmonary capillary transit times that are 60-100 times longer for PMN than for RBC, and this concentrates PMN with respect to RBC in pulmonary capillaries (14,15).Stimuli such as peptide chemoattractants, endotoxin, and smoking are known to decrease PMN deformability and further increase the concentration of PMN in pulmonary capillaries (6,18,27,30). Several in vitro filtration studies have measured the biophysical properties of PMN, particularly their size and deformability, and have shown that these factors determine the magnitude of PMN sequestration in the pulmonary microvessels (6, 18, 27, 30). The importance of the discrepancy between PMN and pulmonary capillary dimensions in causing PMN sequestration in the lung has also been demonstrated during forced expiratory maneuvers in which raised intra-alveolar pressure compresses alveolar microvessels and delays PMN (21). Studies in humans undergoing cardiac catheterization show that alveolar compression results in an immediate arteriovenous difference o...
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.