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The number of Granule cells in the human cerebellar cortex and its quantitative variation with respect to age was studied in seventy human cerebellums using light microscopy. The study revealed a progressive decrease in number of granule cells with increase in the fibre components. The number of granule cells showed statistically significant negative correlation with age. This study provides more information regarding the quantitative histological structure of human cerebellar cortex.

ABSTRACT:The human cerebellum is associated with smooth control of movements and memory. As age advances deterioration is noticed in the cerebellum. The Purkinje cells act as the pivot in the neuronal circuitry of the cerebellum, which initiates and maintains complex, but smooth pursuit movements and it can be identified as one of the factors which cause the decline in movement and memory in humans as age progresses. In the present study a quantitative analysis of the Purkinje cells of the human cerebellum was done using light microscopy in seventy human cerebellums. The tissue collected from post mortem specimen was subject to routine histological processing and the slides studied under light microscopy to assess the diameter and linear density of Purkinje cells. The results of the study showed that the Purkinje cells are seen as a linear interface at the junction of the molecular and granular layer. The number of Purkinje cells was observed to be more at the crests than at the troughs of each folia. The Purkinje cells showed a statistically significant decrease in number after the third decade with ballooning observed around the sixth decade. The study aims to provide information regarding quantitative changes of the Purkinje cells of the human cerebellar cortex so as to enable clinical correlation with age related cerebellar dysfunction. The Purkinje cell bodies are arranged in a sheet, one cell thick at the interface of the molecular and granular layers. Heterotopic Purkinje cells were described in the granular layer by Julio (1971). Purkinje cells are among the largest neurons, in the central nervous system. Palkovits (1971) in his study of the cat cerebellum observed the Purkinje cell diameter to be 29 m. In the rat, according to Smolyaninov (1971), the Purkinje cell bodies are 21 m in diameter and 25 m in length. Inukai (1928) estimated Purkinje cell number in the rat as 5.5 X10 5 in each cerebellum. Hall et al (1975) observed the total number of Purkinje cells in male to be 6-8% higher than that of females. Braitenberg and Atwood (1958) gave the number of Purkinje cells in man as 15X10 6 per cerebellar hemisphere. Bell and Dow (1967) gave the number of Purkinje cells as 5X10 5 , which when compared to other studies were very low. Armstrong and Schild (1970) estimated cell counts in rat as 3.5X10 5 , which was very similar to the findings of Smolyaninov (1971) i.e. 4.5 X 10 5 cells. Palkovits et al (1971) stated the Purkinje cell count in man to be 1.2-1.3X10 6 . Hillmann and Chen (1983) estimated Purkinje cell count to be 2.78X10 5 in rats. The number of Purkinje cell in rat was estimated by Harvey et al (1988) as 3.38X10 5 .

A histological and morphological study of human thymus obtained from autopsy was done. A steady increase in weight of thymus till puberty and thereafter a steady decline was noted. Involution was by fatty infiltration after puberty. Hassall's corpuscles were seen in all the specimens and its size or shape had no relation to the age or involution of the gland. There was an increase in the number of Hassall's corpuscles till puberty after which a progressive decrease was observed.