Insulin-like growth factors (IGFs) are among the primary compounds regulating placental development. In bitches, relative abundance of IGF1, IGF2 and IGFR1 mRNA transcripts have been studied in the pre-implantation uterus and early endotheliochorial placentas. The IGF2 and IGFR1 distribution has also been previously described in the uterus before embryo implantation. The aim of this study was to detect, characterize, and localize the presence of IGF1, IGF2, and IGFR1 in early-developing and mature placentas of dogs. Placentas of 15 bitches were analyzed using immunohistochemistry. The IGFs were located in endometrial epithelium and glands, with the staining pattern and intensity being less in mature placentas. Cytotrophoblast cells (CTB) and syncytiotrophoblast (STB) cells contained both IGFs; the labeling was greater in CTB of the early-developing than mature placentas. The maternal endothelium was positively stained for both IGFs, while the vascular endothelium of the chorioallantoic membrane were only stained for IGF2. The IGFR1 was detected in all cell populations evaluated. Results regarding trophoblastic IGF are quite consistent with those reported in human placentas. Spatiotemporal IGFs/IGFR1 pattern might reflect the occurrence of autocrine and paracrine signaling during placentation in bitches, and the involvement in early placental developmental processes. Furthermore, it is hypothesized that, besides hemotrophic actions of plasma IGFs, endometrial secreted IGFs may promote early placental development through histotrophic signaling.

胰岛素样生长因子 (IGF) 是调节胎盘发育的主要化合物之一。在母犬中，已在植入前子宫和早期内皮层胎盘中研究了 IGF1、IGF2 和 IGFR1 mRNA 转录物的相对丰度。IGF2 和 IGFR1 分布在胚胎植入前的子宫中也已有描述。本研究的目的是检测、表征和定位狗的早期发育和成熟胎盘中 IGF1、IGF2 和 IGFR1 的存在。使用免疫组织化学分析了 15 只母犬的胎盘。IGFs位于子宫内膜上皮和腺体中，成熟胎盘的染色模式和强度较小。细胞滋养层细胞 (CTB) 和合体滋养层 (STB) 细胞均含有 IGF；早期发育的胎盘CTB比成熟胎盘的标记更多。母体内皮对两种 IGF 均呈阳性染色，而绒毛膜尿囊膜的血管内皮仅对 IGF2 染色。在所有评估的细胞群中检测到 IGFR1。关于滋养层 IGF 的结果与人类胎盘中报道的结果非常一致。时空 IGFs/IGFR1 模式可能反映了母犬胎盘发育过程中自分泌和旁分泌信号的发生，以及早期胎盘发育过程的参与。此外，假设除了血浆 IGF 的血液营养作用外，子宫内膜分泌的 IGF 可能通过组织营养信号促进早期胎盘发育。而绒毛膜尿囊膜的血管内皮仅被 IGF2 染色。在所有评估的细胞群中检测到 IGFR1。关于滋养层 IGF 的结果与人类胎盘中报道的结果非常一致。时空 IGFs/IGFR1 模式可能反映了母犬胎盘发育过程中自分泌和旁分泌信号的发生，以及早期胎盘发育过程的参与。此外，假设除了血浆 IGF 的血液营养作用外，子宫内膜分泌的 IGF 可能通过组织营养信号促进早期胎盘发育。而绒毛膜尿囊膜的血管内皮仅被 IGF2 染色。在所有评估的细胞群中检测到 IGFR1。关于滋养层 IGF 的结果与人类胎盘中报道的结果非常一致。时空 IGFs/IGFR1 模式可能反映了母犬胎盘发育过程中自分泌和旁分泌信号的发生，以及早期胎盘发育过程的参与。此外，假设除了血浆 IGF 的血液营养作用外，子宫内膜分泌的 IGF 可能通过组织营养信号促进早期胎盘发育。时空 IGFs/IGFR1 模式可能反映了母犬胎盘发育过程中自分泌和旁分泌信号的发生，以及早期胎盘发育过程的参与。此外，假设除了血浆 IGF 的血液营养作用外，子宫内膜分泌的 IGF 可能通过组织营养信号促进早期胎盘发育。时空 IGFs/IGFR1 模式可能反映了母犬胎盘发育过程中自分泌和旁分泌信号的发生，以及早期胎盘发育过程的参与。此外，假设除了血浆 IGF 的血液营养作用外，子宫内膜分泌的 IGF 可能通过组织营养信号促进早期胎盘发育。