Russo M A, Odorisio T, Fradeani A, Rienzi L, De Felici M, Cattaneo A, Siracusa G
Department of Public Health and Cell Biology, University of Rome Tor Vergata, Italy.
Mol Reprod Dev. 1994 Feb;37(2):157-66. doi: 10.1002/mrd.1080370206.
Nerve growth factor (NGF) is essential for neuronal development and differentiation. Recent reports have shown that its low-affinity receptor (LNGFR) is expressed and developmentally regulated in a broad range of embryonic and adult tissues outside the nervous system, although the functions of the receptor in such tissues remain unknown. Recently, NGF and LNGFR have been detected in adult mouse, rat, and human testis. The results of the present work demonstrate that LNGFR is expressed much before the onset of spermatogenesis in both mouse and rat testis. In situ hybridization shows that the mRNA for LNGFR is expressed in the peritubular cells of the embryonic mouse testis. Immunohistochemical analysis of the rat testis shows LNGFR-expressing cells to be scattered in the intertubular compartment in the embryonic testis, and to become organized in a cellular layer that surrounds myoid cells of the seminiferous tubules during postnatal development. Furthermore, in peripuberal and adult mouse and rat testis we have identified the expression of an abundant and shorter mRNA of 3.2 kb that cross hybridizes to the low-affinity NGF receptor transcript (3.7 kb). This shorter mRNA species, which appears at the beginning of spermatogenesis in the adult, has been identified by in situ hybridization and by Northern blot with RNA isolated from homogeneous populations of meiotic germ cells to be expressed by pachytene spermatocytes and round spermatids. Our results suggest a complex developmental role for LNGFR during testicular morphogenesis and identify the expression, at specific stages of spermatogenesis, of a new germ cell-specific transcript homologous to the receptor RNA.
神经生长因子（NGF）对神经元的发育和分化至关重要。最近的报道表明，其低亲和力受体（LNGFR）在神经系统以外的广泛胚胎和成年组织中表达并受发育调控，尽管该受体在此类组织中的功能尚不清楚。最近，在成年小鼠、大鼠和人类睾丸中检测到了NGF和LNGFR。本研究结果表明，在小鼠和大鼠睾丸中，LNGFR在精子发生开始之前就有表达。原位杂交显示，LNGFR的mRNA在胚胎小鼠睾丸的管周细胞中表达。对大鼠睾丸的免疫组织化学分析表明，表达LNGFR的细胞在胚胎睾丸的小管间区域呈散在分布，在出生后的发育过程中，这些细胞会在围绕生精小管肌样细胞的细胞层中有序排列。此外，在青春期前和成年小鼠及大鼠睾丸中，我们鉴定出一种丰富的3.2 kb短mRNA的表达，它与低亲和力NGF受体转录本（3.7 kb）交叉杂交。这种较短的mRNA种类在成年精子发生开始时出现，通过原位杂交和用从减数分裂生殖细胞同质群体中分离的RNA进行Northern印迹分析，已确定其由粗线期精母细胞和圆形精子细胞表达。我们的结果表明，LNGFR在睾丸形态发生过程中具有复杂的发育作用，并确定了在精子发生的特定阶段，一种与受体RNA同源的新的生殖细胞特异性转录本的表达。
