A NEW MORPHOMETRIC METHOD TO ESTIMATE THE TOTAL NUMBER OF GLOMERULI IN THE OLFACTORY-BULB

A simple morphometnc method for accurate estimation of total number of glomeruli in the olfactory bulb (OB), based on determination of areas of individual glomeruli in representative serial histologic sections from the entire OB, is described. The procedure is best utilized with the help of a computerized program for morphometry, although manual morphometric procedures may also be used. The total volume of all the glomeruli in the OB is determined from the sum of the areas of the individual glomeruli per representative section. This total volume is then divided by the volume of a single glomerulus to obtain the total number of glomeruli in the OB. The method also describes procedures for determining measured mean, corrected mean and maximal diameters and volumes of glomeruli and their distribution in the OB. It also describes two different estimates for the total number of glomeruli, based on whether the mean or maximal glomerular size are utilized. The estimation of total glomerular number by this method does not require the use of correction coefficients such as the Abercrombie's and is independent of tissue shrinkage. Application of the method is illustrated by determining the mean total number of glomeruli in the OB of a 25-day-old rat, which was found to be about 2400. The method can also be used for enumeration of total number of glomeruli in a part of OB or for other relatively large spheroid microanatomical bodies like the taste buds within tongue papillae, follicles in the ovary, etc. The general validity of the method is confirmed by using it to estimate a known total number of spheroid objects placed in a block of agar. © 1990 Oxford University Press.