Table 1.

Cellular composition of the adult rat brain and its subregions

	Cortex		Cerebellum		Olfactory bulb		Remaining areas		Total
	Estimates	CV	Estimates	CV	Estimates	CV	Estimates	CV	Estimates	CV
Weight (mg)	770 ± 113	0.15	272 ± 38	0.14	77 ± 23	0.30	683 ± 153	0.22	1802 ± 313	0.17
n cells (×10⁶)	76.71 ± 3.02	0.04	168.18 ± 12.57	0.07	20.87 ± 5.80	0.28	65.90 ± 9.64	0.15	331.65 ± 8.84	0.03
Cells (×10³)/mg	101.52 ± 17.40	0.17	631.24 ± 128.58	0.20	272.43 ± 33.89	0.12	99.57 ± 23.97	0.24	188.79 ± 36.65	0.19
Percentage of NeuN⁺ nuclei	40.58 ± 5.34	0.13	82.78 ± 3.24	0.04	53.60 ± 4.28	0.08	28.12 ± 3.14	0.11	60.31 ± 2.35	0.04
n neurons (×10⁶)	31.02 ± 3.03	0.10	139.17 ± 11.19	0.10	11.26 ± 3.68	0.10	18.68 ± 4.24	0.10	200.13 ± 12.17	0.06
Neurons (×10³)/mg	41.09 ± 8.00	0.19	522.69 ± 108.85	0.21	146.92 ± 27.50	0.19	27.81 ± 6.17	0.22	113.98 ± 23.16	0.20
n non-neuronal cells (×10⁶)	45.69 ± 5.68	0.12	29.01 ± 6.28	0.08	9.61 ± 2.42	0.33	47.22 ± 5.98	0.23	131.52 ± 6.11	0.05
Percentage of brain weight	42.86 ± 1.74	0.04	15.17 ± 1.00	0.06	4.24 ± 0.77	0.18	37.72 ± 2.55	0.07
Percentage of all cells	23.15 ± 1.23	0.05	50.69 ± 3.16	0.06	6.31 ± 1.83	0.29	19.86 ± 2.74	0.14
Percentage of all neurons	15.48 ± 0.94	0.06	69.57 ± 4.37	0.06	5.64 ± 1.90	0.34	9.31 ± 1.96	0.21

Values are mean ± SD. CV = SD/mean. n cells, total number of cells (in millions); Cells (×10³)/mg, cell density per milligram of tissue (in thousands); n neurons, total number of neurons (in millions); Neurons (×10³)/mg, neuronal density per milligram of tissue (in thousands); n non-neuronal cells, total number of non-neuronal cells (in millions, defined as n cells - n neurons). Large SD and CV values for olfactory bulb weight can be partly explained by the difficulty of dissecting this structure undamaged.