Table 1.

Selected milestones in hippocampal development of human, rat and primate^a

Event	Human	Rat	Primate	Refs
General
Maximal growth velocity	2–3 Postnatal months	8–12 Postnatal days	105–120 Prenatal days	[62–65]
Hippocampal volume approximates that of adult	10 Postnatal months	11–30 Postnatal day	Birth	[62,65–67]
Hippocampal-dependent learning and memory established	4–5 Postnatal years	15–16 Postnatal days	1 Postnatal month	[68–71]
Neuronal formation
Birth of pyramidal cells	First half of gestation	Second half of gestation	First half of gestation	[71–74]
Onset:	Before 15 prenatal weeks	~15 Prenatal days	38 Prenatal days
End:	24 Prenatal weeks	~19 Prenatal days	~80 Prenatal days
Birth of granule cells of dentate gyrus	~70% Prenatal (majority by 34 weeks)	~85% Postnatal (majority by 1 postnatal month)	~85% Prenatal (majority by end of 1 postnatal month)	[71–74]
Onset	13–14 Prenatal weeks	~18 Prenatal days	~38 Prenatal days
End	Throughout life	Throughout life	Throughout life
Differentiation and synaptogenesis
‘Thorny excrescences’ on proximal CA3 pyramidal cell dendrites	Postnatal years	1 Postnatal month	1 Postnatal year	[75–78]
Onset	3–7 Postnatal month	~9 Postnatal days	Birth
Maturation	3–5 Postnatal years	21 Postnatal day	3 Postnatal months
Pedunculate spines on distal CA3 pyramidal-cell dendrites	Postnatal years	1 Postnatal month	1 Postnatal year	[75–78]
Onset	Birth	7 Postnatal days	Birth
Maturation	3–5 Years	21 Postnatal days	9–12 Postnatal months
Peak synapse overshoot in dentate gyrus	1–2 Postnatal years	9–14 Postnatal days	4–5 Postnatal months	[67,77–79]
Synapse density reaches adult levels in molecular layer	7–10 Postnatal months	21 Postnatal days	Birth	[65,67,71,78]
Period of maximal mossy-cell differentiation in dentate gryus	7–30 Postnatal months (adult-like by 5 years)	7–14 Postnatal days (adult-like by 14 days)	Late prenatal to 1 postnatal month (adult-like by 9–10 months)	[75,76,78]
Afferent input
Entorhinal cortex to dentate gyrus	19–20 Prenatal weeks	17 Prenatal days	47–56 Postnatal days	[80–82]
Supramammillary afferents reach juxtagranular and CA2 pyramidal-cell layers	~20 Prenatal weeks	Presumed first postnatal week	~109–165 Prenatal days	[83,84]

^aGestation lasts 270–280, 21 and 165 days in human, rat and rhesus monkey, respectively.