Wang R A, Nakane P K, Koji T
Department of Histology and Cell Biology, Nagasaki University School of Medicine, Japan.
Biol Reprod. 1998 May;58(5):1250-6. doi: 10.1095/biolreprod58.5.1250.
Germ cell degeneration is common in mammalian testes during the developmental as well as the adult period. To investigate the extent and mechanisms of male germ cell death during fetal and neonatal life, the testes of mice at various fetal and postnatal ages extending from 13 days of gestation to 7 wk after birth were examined by electron microscopy and/or terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling (TUNEL). Electron microscopy revealed that the number of cells with typical features of spermatogenic cell apoptosis was highest at 13 days of gestation, coinciding with the time of immigration of primordial germ cells into gonads. A second peak was observed around 10-13 days after birth when the first wave of spermatogenesis had started and active spermatogonial proliferation was present. Surprisingly, we found a significant number of dying cells around birth, which exhibited morphological features of necrotic death. In agreement with the results of electron microscopy, TUNEL staining revealed that the dying germ cells present around birth were TUNEL negative, while positive nuclei were abundant in the lumen of seminiferous tubules of testes of 10- to 13-day-old mice. To investigate the mechanisms of induction of germ cell death, we examined the expression of Fas antigen immunohistochemically using rabbit antiserum raised against synthetic peptides for part of mouse Fas antigen. We found that among various developmental stages investigated, positive immunostaining for Fas antigen was present between 17 days of gestation and 1 day after birth, with the most intensive staining occurring on 17 days of gestation. Therefore, Fas-induced pathways may be implicated in embryonic male germ cell death, not prepubertal spermatogenic cell death.
生殖细胞退化在哺乳动物睾丸的发育阶段以及成年期都很常见。为了研究胎儿期和新生儿期雄性生殖细胞死亡的程度及机制，我们通过电子显微镜和/或末端脱氧核苷酸转移酶介导的dUTP缺口末端标记法（TUNEL），对从妊娠13天到出生后7周不同胎儿期和出生后年龄段的小鼠睾丸进行了检查。电子显微镜显示，具有生精细胞凋亡典型特征的细胞数量在妊娠13天时最高，这与原始生殖细胞迁移到性腺的时间一致。在出生后约10 - 13天观察到第二个峰值，此时第一波精子发生开始且存在活跃的精原细胞增殖。令人惊讶的是，我们发现在出生前后有大量死亡细胞，它们呈现出坏死性死亡的形态特征。与电子显微镜结果一致，TUNEL染色显示出生前后存在的死亡生殖细胞TUNEL阴性，而在10至13日龄小鼠睾丸的生精小管管腔中阳性细胞核丰富。为了研究生殖细胞死亡诱导的机制，我们使用针对小鼠Fas抗原部分合成肽产生的兔抗血清，通过免疫组织化学方法检测了Fas抗原的表达。我们发现在所研究的各个发育阶段中，Fas抗原的阳性免疫染色出现在妊娠17天至出生后1天之间，最强染色出现在妊娠17天。因此，Fas诱导的途径可能与胚胎期雄性生殖细胞死亡有关，而非青春期前的生精细胞死亡。
