Department of Morphology, Institute of Biological Sciences, Federal University of Minas Gerais, Belo Horizonte, MG, Brazil.
Reproduction. 2011 Jul;142(1):145-55. doi: 10.1530/REP-10-0431. Epub 2011 Apr 26.
Despite the knowledge of spermatogonial biology in adult mice, spermatogonial development in immature animals has not been fully characterized. Thus, the aim of this study was to evaluate the ontogeny of the morphological development of the spermatogonial lineage in C57BL/6 mouse testis, using high-resolution light microscopy. Spermatogonial morphology, chronology, and absolute number were determined for different ages postpartum (pp). The morphology of spermatogonia in immature mice was similar to that of adult spermatogonia, although their nuclear diameter was slightly smaller. The A(1) spermatogonia were first observed on day 2 pp, and only 24 h later, differentiating type A(3) and A(4) spermatogonia were observed in the seminiferous cords. This result indicated a shortening of the spermatogonial phase for immature mice of about ∼2.5 days when compared with adult mice and suggests that gonocytes and/or A(1) spermatogonia could directly become A(4) spermatogonia, skipping the developmental sequence of type A spermatogonia. These A(4) spermatogonia are functional as they develop into type B spermatogonia by day 5 pp. At day 8 pp, while differentiation to spermatocytes begins, the A(und) spermatogonia reach their maximal numbers, which are maintained through adulthood. The various details of the spermatogonial behavior in immature normal mice described in this study can be used as a baseline for further studies under experimental or pathological conditions.
尽管人们对成年小鼠精原细胞生物学有了一定的了解，但未成熟动物精原细胞的发育尚未得到充分描述。因此，本研究旨在使用高分辨率显微镜评估 C57BL/6 小鼠睾丸精原细胞谱系的形态发育的个体发生。针对不同产后天数（pp）确定精原细胞的形态、发生顺序和绝对数量。未成熟小鼠的精原细胞形态与成年精原细胞相似，尽管其核直径略小。A(1)精原细胞最早在第 2 天 pp 时观察到，仅 24 小时后，在生精小管中观察到分化的 A(3)和 A(4)精原细胞。这一结果表明，与成年小鼠相比，未成熟小鼠的精原细胞阶段缩短了约 2.5 天，表明卵原细胞和/或 A(1)精原细胞可以直接成为 A(4)精原细胞，跳过 A 型精原细胞的发育序列。这些 A(4)精原细胞是有功能的，因为它们在第 5 天 pp 时发育成 B 型精原细胞。在第 8 天 pp 时，当开始向精母细胞分化时，A(und)精原细胞达到其最大数量，并在成年期保持不变。本研究中描述的未成熟正常小鼠精原细胞行为的各种细节可作为在实验或病理条件下进一步研究的基础。
