Laboratory of Cellular Biology, Department of Morphology, Institute of Biological Sciences, Federal University of Minas Gerais, Belo Horizonte, MG, Brazil.
Theriogenology. 2010 Jul 1;74(1):11-23. doi: 10.1016/j.theriogenology.2009.12.014. Epub 2010 Feb 26.
Although seminiferous tubule maturation in horses begins in the central area of the testis, this process is thought to occur randomly throughout the testis in most mammals. Studies in our laboratory revealed that the establishment of spermatogenesis may not be a synchronous event in the testicular parenchyma of pigs. The objectives of the present study were to evaluate the pattern of seminiferous cord/tubule maturation and the morphological and functional characteristics of testicular somatic cells during postnatal development in three regions of the pig testis: a) near the tunica albuginea (TA); b) in the transitional area between the seminiferous tubules and mediastinum (TR); and c) in the intermediate area (ID) between the TA and TR. Based on the diameter of seminiferous cords/tubules, nucleus size of Sertoli cells and fluid secretion, mainly at 90 and 120 d of age, seminiferous tubule maturation was more advanced in the ID and TR. The mitotic activity of Sertoli cells was higher (P<0.05) in the TR than the ID and TA at 7 and 120 d. Except for the mitotic index of the Leydig cells, which was lower (P<0.05) in the ID at 7, 30, and 180 d than in the TA and TR, other Leydig cell ebd points, e.g., individual cell size, nuclear volume, and cytoplasmic volume, were consistently higher (P<0.05) in the ID, suggesting that steroidogenesis was more active in this region during the period investigated. Overall, we inferred that Leydig cells in the ID may play a pivotal role in postnatal testis development in pigs and this type of cell is likely related to asynchronous testicular parenchyma development, with the transitional area providing the primary zone for growth of seminiferous tubules.
虽然马的生精小管成熟始于睾丸的中央区域，但在大多数哺乳动物中，这一过程被认为是随机发生在整个睾丸中的。我们实验室的研究表明，精子发生的建立可能不是猪睾丸实质中同步发生的事件。本研究的目的是评估生精索/小管成熟的模式以及在三个猪睾丸区域（a）靠近白膜（TA）；b）在生精小管和纵隔之间的过渡区（TR）；c）在 TA 和 TR 之间的中间区（ID））在出生后发育过程中睾丸体细胞的形态和功能特征。基于生精索/小管的直径、支持细胞的核大小和液体分泌，主要在 90 和 120 天龄时，ID 和 TR 中的生精小管成熟度更高。支持细胞的有丝分裂活性在 TR 中高于 ID（P<0.05），在 7 和 120 天龄时。除了 Leydig 细胞的有丝分裂指数在 7、30 和 180 天龄时低于 ID（P<0.05）外，其他 Leydig 细胞的各点，例如单个细胞大小、核体积和细胞质体积，在 ID 中一直较高（P<0.05），表明在研究期间该区域的类固醇生成更为活跃。总体而言，我们推断 ID 中的 Leydig 细胞可能在猪出生后睾丸发育中发挥关键作用，这种细胞可能与睾丸实质的不同步发育有关，过渡区是生精小管生长的主要区域。
