James A. Freeman

Intestinal fat and iron transport, goblet cell mucus secretion, and cellular changes in protein deficiency observed with the electron microscope.

M UCH of the surge of in te res t in cytology t ha t has occur red in the last 2 decades can be a t t r i b u t e d to s tudies w i th the e lec t ron microscope . T h i s i n s t r u m e n t no t on ly has p r o v i d e d for d i r ec t obse rva t ion of organel les in a cell, b u t also in some cases has p e r m i t t e d v i sua l i za t ion of m o l e c u l a r s t ruc tu re of organel les . As a resul t , the concep t of ce l lu l a r s t ruc tu re has been a l t e red grea t ly in the pas t few years. T h i s p a p e r wi l l rev iew the cu r r en t concept of fine s t ruc tu re of the n o r m a l j e j u n a l ep i thel ia l ceil, d e m o n s t r a t e o rgane l les of the cell t ha t f u n c t i o n in fat a n d i r o n t r a n s p o r t a n d mucus secret ion, a n d descr ibe changes in o rgane l les seen wi th p r o t e i n deficiency in an e x p e r i m e n t a l an ima l .

A fine structural study of renal glycosuria

Abstract Five patients with a clinical diagnosis of renal glycosuria were subjected to renal function tests and percutaneous needle biopsies of the kidney; the biopsy specimens were studied by light and electron microscopy. Basement membrane thickening was demonstrated in the proximal tubules of one patient who was felt to be in a pre-diabetic stage of orthoglycemic glycosuria. The other patients were felt to represent renal glycosurics with a decrease in the tubular maximum reabsorption of glucose. In the patients representing idiopathic renal glycosuria, no fine structural abnormality could be detected in any segment of the proximal convoluted tubule. The inability to demonstrate fine structural abnormality suggests the glucose reabsorptive defect to be either a biochemical deficit or, as Oliver has postulated, a decrease in the number of physiologically active units created by a “shortening” of the proximal convoluted tubule.