Russo M A, Giustizieri M L, Farini D, Siracusa G
Department of Public Health and Cell Biology, University of Rome Tor Vergata, Italy.
Ital J Anat Embryol. 1995;100 Suppl 1:543-51.
Nerve growth factor (NGF) and the other members of the family of neurotrophic factors (the neurotrophin) are essential for neuronal development and differentiation. Neurotrophins interact with two types of cell surface receptors: a low-affinity receptor (p75 NGF-R) and a high-affinity tyrosine kinase receptor belonging to the trk proto-oncogene family, both expressed in the nervous system and in certain non-neuronal tissues. Recently, NGF immunoreactivity and mRNA have been detected in the testis of the adult mouse, rat and human. In the present report we demonstrate the expression of p75 NGF-R during early gonadal development, by mesenchymal cells of the embryonic mouse and rat testis. In the embryonic testis p75 NGF-R-positive cells are spread through the interstitial compartment; during postnatal development they become organized in a cellular layer that surrounds differentiating myoid cells of the seminiferous tubule. Our results also show the expression in the peripuberal and adult mouse and rat testis, of an abundant and shorter transcript of 3.2 kb that cross-hybridizes to the receptor mRNA (3.7 kb). This new mRNA species, which appears at the beginning of spermatogenesis, is expressed by pachytene spermatocytes and round spermatids.
神经生长因子（NGF）和神经营养因子家族的其他成员（神经营养蛋白）对于神经元的发育和分化至关重要。神经营养蛋白与两种类型的细胞表面受体相互作用：一种低亲和力受体（p75 NGF-R）和一种属于trk原癌基因家族的高亲和力酪氨酸激酶受体，二者均在神经系统和某些非神经元组织中表达。最近，在成年小鼠、大鼠和人类的睾丸中检测到了NGF免疫反应性和mRNA。在本报告中，我们证明了p75 NGF-R在胚胎小鼠和大鼠睾丸的间充质细胞早期性腺发育过程中的表达。在胚胎睾丸中，p75 NGF-R阳性细胞分布于间质区；在出生后发育过程中，它们形成围绕生精小管中分化的肌样细胞的细胞层。我们的结果还显示，在青春期前和成年小鼠及大鼠睾丸中，存在一种丰富的3.2 kb较短转录本，它与受体mRNA（3.7 kb）交叉杂交。这种新的mRNA种类在精子发生开始时出现，由粗线期精母细胞和圆形精子细胞表达。
