In the present study, we cloned full-length cDNAs for epidermal growth factor (EGF), EGF receptor (EGFR), and three truncated forms of EGFR (EGFR15, 12, and 8) from the zebrafish ovary. Zebrafish EGF was predominantly expressed in the ovary and testis, while EGFR and its truncated forms were highly expressed in all tissues examined except the liver. In the ovary, the expression of EGF seemed to be more abundant in the follicles of early stages, while EGFR had much higher expression levels at later stages. Interestingly, although EGF was expressed in both the follicle cells and oocytes, its expression level was significantly higher in the oocytes. However, the expression of EGFR was mainly restricted to the follicle cells with little expression in the oocytes. The unique spatial patterns of EGF and EGFR expression within the follicle suggest that EGF may serve as a messenger from the oocyte to signal the follicle cells. EGF strongly stimulated the expression of both activin βA and βB, while it suppressed basal and hCG-induced follistatin expression in cultured follicle cells. These results, together with the evidence that EGF was predominantly expressed in the oocytes whereas EGFR was expressed in the follicle cells, strongly suggest that EGF is likely a potential paracrine/juxtacrine factor from the oocytes to regulate the function of the follicle cells.
You have requested a machine translation of selected content from our databases. This functionality is provided solely for your convenience and is in no way intended to replace human translation. Neither BioOne nor the owners and publishers of the content make, and they explicitly disclaim, any express or implied representations or warranties of any kind, including, without limitation, representations and warranties as to the functionality of the translation feature or the accuracy or completeness of the translations.
Translations are not retained in our system. Your use of this feature and the translations is subject to all use restrictions contained in the Terms and Conditions of Use of the BioOne website.