Time after first
ejaculation (months) Average volume
(milliliter) Liquefaction Average sperm concentration
(million sperm/milliliter)
0 0.5 Noa 0
6 1.0 Noa 20
12 2.5 No/Yesb 50
18 3.0 Yesc 70
24 3.5 Yesc 300

^a Ejaculate is jellylike and fails to liquify.
^b Most samples liquify. Some remain jellylike.
^c Ejaculate liquifies within an hour.

Control from the central nervous system
To map the neuronal activation of the brain during the ejaculatory response, researchers have studied the expression of c-fos, a proto-oncogene expressed in neurons in response to stimulation by hormones and neurotransmitters.[17] Expression of c-fos in the following areas has been observed:[18][19]

medial preoptic area (MPOA)
lateral septum, bed nucleus of the stria terminalis
paraventricular nucleus of the hypothalamus (PVN)
ventromedial hypothalamus, medial amygdala
ventral premammillary nuclei
ventral tegmentum
central tegmental field
mesencephalic central gray
peripeduncular nuclei
parvocellular subparafascicular nucleus (SPF) within the posterior thalamus