In this experiment, the PAP was used as a specific marker to label the follicular dendritic cells (FDC) and their possible precursors in the spleens of postnatal rats at 21, 27, 34, 41 and 48 days respectively, and the changes of the labeled cells were studied under TEM. In 21-day-old rats the labeled cells were of the histological feature resembling fibroblastic reticulum cells(FRC). As the rats getting elder, the shape and structure of the labeled cells changed. The shape of t he cells and nuclei changed from ellipse to irregular. The heterochromatin decreased and so did the microfilaments in the cytoplasm. The cytoplasmic processes increased in number, length and complexity. The relatively smooth cell surface became folding and invaginating. By the 48 days after birth the labeled cells possessed the features of the FDC. The result implys that the FDC might originate from FRC.

HRP-anti-HRP complex was injected into BALB/c mice through the tail vein. 24 hours later, the spleens of mice were removed, fixed and cut into slices. After incubation in DAB/H_2O_2 the follicular dendritic cell (FDC) distribution area could be defined at a certain part of lymph nodule. Light microscopic and stereologic analysis study on the lymphocytes at intra- and extra- FDC distribution area were carried out. The results revealed that lymphocytes at intra- and extra- FDC distribution area were composed of various lymphocytes populations of different sizes. The cell populations at intra-FDC distribution area were mainly composed of large and medium sized lymphocytes, while the populations at extra-FDC distribution area were mainly medium sized and small lymphocytes. As a result, FDC always exists on the location where lymphoblastic phenomenon appears. This indicates that FDC has certain relation with the lymphoblastic phenomenon.

This paper reports some histochemical,scanning and transmission electron mic-roscopical features of thymic nurse cell(TNC)of human fetuses.The results showedthat TNCs were all negative for ANAE,AcP,AlP,ATPase,5'-Nase and PAS.TNCcontained various numbers of lymphocytes.Some intracytoplasmic lymphocytes werepositive for ANAE,AcP,AlP and ATPase.Their ANAE positive percentage deter-mined were 26.8%.However,ANAE positive percentage of extracytoplasmic lym-phocytes of TNC were 51.3%.Our data demonstrated that there was significant dif-ference between these two ANAE positive percentages,P

Objective:To evaluate the safety and efficacy of a dedicated neonatal-infant brain 0.35 T MRI system.Methods:A dual-center controlled clinical trial was conducted with single-arm objective performance criteria. From June to July 2020, sixty-six infants aged 0-12 (6.3±3.4) months were recruited from Children′s Hospital of Soochow University and the First People′s Hospital of Lianyungang prospectively. All infants underwent brain MRI with a dedicated neonatal-infant 0.35 T brain MRI system, using the dedicated two-channel transceiver head coil. MRI protocol included spin echo T 1WI, fast spin echo T 2WI, fluid attenuated inversion recovery, diffusion weighted imaging and 3D gradient echo sequence. MRI sequences were set with three orientations (axial, sagittal and coronal). Each case received at least two scanning planes and two scanning sequences. Five-point Likert scoring system was used to evaluate the image quality of acquired images, and the target value was set as at least 3 points per image. The temperature, heart rate and breathe of the infants were recorded before and after MRI; the acoustic noise of the MRI system was measured during the scanning process; and the adverse reactions were recorded if presented. Results:Five infants successfully completed their examination during non-sedated sleep in a single attempt, and 61 infants after sedation with chloral hydrate. Based on MRI-based five-point Likert scoring system, 41 cases achieved a score of 5, 21 cases with a score of 4 and 4 cases with a score of 3. Cases with score of 3 was due to movement of the infants during the scan, which resulted in motion related artifacts. The vital signs of all infants showed stable before and after imaging, with heart rate of (126.8±12.9) beats per minute, breathe of (38.2±6.8) times per minute. It was found that 47 cases showed no sign of temperature raise after brain MRI, 15 cases had less than 0.3 ℃ raise and 4 cases had 0.3 ℃ to 0.5 ℃ raise. The noise recorded during the scanning process was (57.5±1.8) dB(A). One case had mild diarrhea on the day of MR scan, and the symptoms disappeared on the second day without treatment; no adverse reactions were found for the rest subjects.Conclusion:Dedicated neonatal-infant 0.35 T brain MRI system allows data acquisition with high safety and excellent image quality, which has potentials in the clinical applications.