Filtrate passes from the glomus to the coelom.
If it extends over one segment or less, it is referred to as a glomerulus. I would prefer to refer to integrated vascular structures as glomeruli, and external vascularized structures as glomera. This pocket is vascularized by a blood vessel from the dorsal aorta. The enlargements of the figures below are very nice, and worth the download time. The development of the pronephros and segmental duct in amphibia.