The bonds shall bear the manual or facsimile signatures of such officers of the issuing city or county as may be designated in the resolution authorizing the bonds and such signatures shall be the valid and binding signatures of the officers of the city or county, notwithstanding that before the delivery thereof and payment therefor any or all of the persons whose signatures appear thereon have ceased to be officers of the city or county. The validity of the bonds shall not be dependent on, nor affected by, the validity or regularity of any proceedings relating to the home mortgages for which the bonds are issued. The resolution authorizing the bonds may provide that the bonds shall contain a recital that they are issued pursuant to this part, and the recital shall be conclusive evidence of their validity and of the regularity of their issuance.