Scanning Electron Microscopic Study on the Saccus Vasculosus of the Rainbow Trout

Ultrastructural Study of the Evolution of Globules in Coronet Cells of the Saccus Vasculosus of an Elasmobranch (Scyliorhinus canicula L.), with some Observations on Cerebrospinal Fluid‐Contacting Neurons

“…6, some cells with dilated globules have lost a num-ber of them and 'stumps' of shed globules are clearly visible on the apical protrusion of the cell. None of these stages corresponds with those described by Shimada (1976). 1, 7).…”

“…The globule size varies somewhat between cells but is very uniform in the same cell. We have identified this morphology as the 'mature' stage of globules of coronet cells, which corresponds to cells of type I or 'Botryoid' cells described by Shimada (1976). These cells are exclusively located at the saccus vasculosus surface and a small transitional zone towards the median eminence.…”

“…CSF-contacting neurons of the dogfish have long cilia, such as those described in Actinopterygians, but their small intraventricular protrusions are very different from the larger ones described in bony fishes (Jansen and Flight 1969, Shimada 1976, Kotrschal et ul. 1985a.…”

“…Also, Shimada (1976) suggests that 'flowerlike' coronet cells with globules of various shapes are developmental stages in adult trout. Interestingly, unlike Shimada (1976), we have not found different globule morphologies in the same cell and we think their images do not agree with those of the dogfish. Interestingly, unlike Shimada (1976), we have not found different globule morphologies in the same cell and we think their images do not agree with those of the dogfish.…”

“…Scanning electron microscopy (SEM) studies in adult trout showed two coronet cell types, one of which was considered a developmental stage (Emanuelsson andvon Mecklenburg 1974, Shimada 1976). 1972, Shimada 1976, Kotrschal et al 1985a. 1970, Zimmer-mann and Altner 1970, Vigh et af.…”