Main references (data with "?" refer to a reasonable guess; with "??" to a total guess):
Morphology: Claiborne et al., 1990; Van Pelt et al., 1997.
Number and connectivity: Amaral et al., 1990; Patton and McNaughton, 1995.
Biochemistry and physiology: Patton and McNaughton, 1995, and references therein.

Type: Principal cells, excitatory (glutamate).
Number: 1,000,000.
Location (Dentate Gyrus): Soma in granule cell layer, dendrites in molecular layer, axons (mossy fibres) in hilus.

Explicit morphological data: Not available (yet).

Notes: Patton and McNaughton (1995) report that 400 synapses (~7% of excitatory input) need to be activated on the dendrites in order to trigger an action potential on the soma.
 

Connectivity:

Axonal output (number of cells contacted, with one synapse unless specified; in parenthesis: number of cells of that type):
8 DG bc (10,000)
8? DG mopp (10,000)
135 DG gpc (15,000)
24 DG mc (30,000)
0.8 DG cc (1000)
?? CA3 pc (200,000)
?? CA3 ri (4000)
?? CA3 oi (4000)
?? CA3 cc (1000)

Axo-somatic input:
GABA 140 DG bc x2 (10,000) on soma
GABA 6 DG cc x8 (1000) on axon

Dendritic input:
Glu 1080 mc (30,000) on spines?
GABA 600 gpc (15,000) on shafts?
AcCh ?? SHP on spines and shaft (50%-50%?)
Glu 3400 EC (200,000) on spines
GABA 140x2? mopp (10,000) on shafts??
 

Biochemistry:
 
Spines: AMPA, NMDA, mGlu, GABA-A, mAcCh, ER.
Dendrites: GABA-B, mAcCh, C_Ca, E_sp, E_C, E_P.
Soma: GABA-A, GABA-B, C_Na, C_K?, E_D.
Axon: GABA-A, GABA-B, C_Na, C_K?, E_P,E_C.
 

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