Crivellato E, Nico B, Battistig M, Beltrami C A, Ribatti D
Department of Medical and Morphological Researches, Anatomy Section, University of Udine Medical School, Piazzale Kolbe no. 3, 33100 Udine, Italy.
Anat Embryol (Berl). 2005 Feb;209(3):243-9. doi: 10.1007/s00429-004-0439-5. Epub 2004 Nov 16.
Thymic mast cells were studied by light and transmission electron microscopy in chicken embryos during organogenesis. Mast cells made their first appearance at day 15. At days 16 and 17, there was a burst of mast cell development with a peak of 278 +/- 54 cells/mm(2) at day 16. Then, mast cell density decreased until hatching. During the whole embryonic period, about 80% of mast cells localized to the thymic medulla. In the cortex, they were less numerous, and some rare mast cells could be identified in the capsule and septa. Thymic mast cells could be recognized in association with hematopoietic foci, but frequently they grew independently from areas of hematopoiesis and appeared as single cells interspersed among thymocytes, thymic epithelial cells, and interdigitating cells. They were often recognized in close relationship with the scanty and delicate extracellular matrix of the developing gland. Viewed by electron microscopy, mast cells were relatively small cells, with a few secretory granules. Exocytosis was never seen, but, notably, granules emptied in a piecemeal degranulation fashion. This study demonstrates that the chicken thymus is a site of mast cell development during embryogenesis. The high mast cell density we found suggests a possible role for these cells during thymus organogenesis.
在器官发生期，利用光学显微镜和透射电子显微镜对鸡胚中的胸腺肥大细胞进行了研究。肥大细胞在第15天首次出现。在第16天和第17天，肥大细胞发育迅速，第16天达到峰值，为278±54个细胞/mm²。然后，肥大细胞密度下降直至孵化。在整个胚胎期，约80%的肥大细胞定位于胸腺髓质。在皮质中，它们数量较少，在被膜和间隔中可识别出一些罕见的肥大细胞。胸腺肥大细胞可与造血灶相关联，但它们常独立于造血区域生长，表现为散在于胸腺细胞、胸腺上皮细胞和交错突细胞之间的单个细胞。它们常与发育中腺体稀少且精细的细胞外基质密切相关。通过电子显微镜观察，肥大细胞是相对较小的细胞，含有少量分泌颗粒。从未观察到胞吐作用，但值得注意的是，颗粒以逐片脱颗粒的方式排空。本研究表明，鸡胚胸腺是胚胎发育过程中肥大细胞发育的场所。我们发现的高肥大细胞密度提示这些细胞在胸腺器官发生过程中可能发挥作用。
