Morphology and Quantification of Juxtaglomerular Cells of the Chicken Kidney

Abstract

Morphology and distribution of the juxtaglomerular (JG) cells of chicken kidneys were ontogenetically studied by light and electron microscopy. JG cells contained fine secretory granules having a diameter of about 350 nm and myofibrils in their cytoplasm. Following three types of JG cells were classified tentatively by their positions for the convenience of description: 1) A type: located at the walls of the glomerular arterioles; 2) V type: located at the paravascular poles; 3) M type: located in the mesangial regions. There were no morphological differences among the granular characteristics of the three types of JG cells; however, it was noted that some JG cells of M type showed obscure association with neighboring basement membranes of glomerular capillaries and contained almost no myofibrils in their cytoplasm. Ontogenetically, JG cells were initially detected in embryos of 19 days of incubation, and their histoplanimetrical frequency was increased until the first day of posthatching life. However, a prominent decrease in the frequency was characteristically estimated at the second posthatching day. Thereafter, their relative histoplanimetrical values were observed to tend to increase constantly. Concerning the frequencies estimated among the three types of JG cells for the period of 1 to 15 posthatching weeks, the relative frequency of the glomeruli containing A type of JG cells was clearly decreased in contrast with that of M type. However, there was no conspicuous changes of relative histoplanimetrical values in the glomeruli containing V type of JG cells throughtout the investigated period.