Some Observations on the Ultrastructure of the Adenohypophysis of the Rabbit

Abstract

SUMMARY The ultrastructure of the adenohypophysis of the rabbit is described preliminary to reporting changes after experimental procedures. Fixation by perfusing with gluteraldehyde enabled selected regions of the gland to be removed with accuracy. Separate descriptions of the pars distalis proper, zona tuberalis, pars tuberalis and pars intermedia are therefore included. In the pars distalis proper four types of granular cell were recognized although their function cannot be accurately determined. For convenience, therefore, they have been designated 1, 2, 3 and 4. In addition a fifth type of cell (type 5) is described which is also present in the other areas. This cell, as well as having possible phagocytic functions, appears to be concerned in the formation of a perivascular channel. Two types of cell are recognized in the zona tuberalis, which are similar in appearance to the 3 and 4 cells of the pars distalis, although not necessarily identical in function. The characteristic cells of the pars tuberalis are rich in cytoplasmic RNA and contain large numbers of intracellular fibrils. It is suggested that the ribosomes are concerned in the synthesis of a sedentary protein which may take the form of the microfibrils. The pars intermedia contains a predominant cell type with large granules of varying density. The relationship of these granules to the specific hormone is discussed.

Ultrastructural Changes in the Adenohypophysis of Metyrapone-Treated Rabbits

“…The granules, about 200 of which were counted, were substantially larger than those of the cells described above, having a mean diameter of 210 nm (180-290 nm). Neither of these cell types were positively identified in control animals used in this and previous investigations (Young, Foster & Cameron, 1965).…”

“…These were the cells containing granules with a mean diameter of 150 nm. Although the mean diameter of the granules of these cells and of the gonadotrophs (type 3 cells) are virtually identical, the distribution of the granular endoplasmic reticulum and of the mitochondria is significantly different (see Young et al 1965). Hymer & McShan (1963 and McShan (1971), in their studies of the secretion granules isolated by density gradient ultracentrifugation from the rat adenohypophysis, concluded that the ACTH activity resided in the fraction containing granules less than 140 nm in diameter.…”

The Fine Structure of the Human Pituitary Chromophobe Adenoma with Special Reference to the Classification of this Tumor

“…16) (CARDELL and KNIGHTON, 1966;FUKUMITSU, 1964;GUSEK, 1962;LUSE, 1962;SCHELIN, 1962;WECHSLER and HOSSMANN, 1965 RINEHART, 1954 a, b, 1955;HYMER, MCSHAN and CHRISTIANSEN, 1961;LUNDIN and SCHELIN, 1962;rat, BARNSE, 1962;SANG, 1962;UCHIDA, 1967;YAMADA and SANO, 1960;mouse, SALAZAR, 1963;YOUNG, FOSTER andCAMERON, 1965, 1966;rabbit, CARDELL, 1964 a, b;salamander, OZTAN, 1966;fish MCSHAN and RIS, 1960;HYMER and MCSHAN, 1963;MCSHAN, 1964;PERDUE and MCSHAN, 1962).…”

Some Light- And Electron-Microscopical Observations on the Pars Intermedia of the Pituitary Gland of the Rabbit

“…A few earlier studies of this region have also been carried out in reptiles and fishes, but so far as mammals are concerned the major emphasis has been on the rat (Kurosumi, Matsuzawa & Shibasaki, 1961;Ziegler, 1963;Kobayashi, 1964Kobayashi, , 1965Howe & Maxwell, 1968;Howe & Thody, 1970) and the ferret (Holmes, 1961(Holmes, , 1962Vincent & Kumar Anand, 1968;Vincent, 1969). In the rabbit we briefly referred to this somewhat uncharted region of the adeno¬ hypophysis in an earlier paper (Young, Foster & Cameron, 1965). Since then further work has been carried out both at the light and electron microscopical levels and the results are set down below.…”