title: Interference of sex-related factors in the response of liver cells to experimental mitotic stimuli.
abstract: Stimulation of liver cell multiplication was obtained under two different experimental conditions. (1) A single injection of casein solution resulted in (a) an identical synchronized mitotic wave response in 10-day old male and female rats and (b) a significantly lower response in adult male rats compared to females, a difference which was reduced by castration of males at birth but essentially maintained if animals were operated when 10 days old. (2) Partial hepatectomy shortly after puberty resulted in active hepatocyte multiplication occurring 3 hr earlier in females were ovariectomized at birth and significantly reduced when they were spayed at a later age. Hepatocytes of castrated females entered actively into S phase 2 hr later than the sham-operated controls. Unilateral ovariectomy on the other hand indicated that during compensatory and/or hypercompensatory activity of the single ovary there was a maximum difference between the male and female rate of [3H]thymidine uptake in liver nuclei 20 hr after hepatectomy. A further kinetic study (t = 25, 30,40, 65, 90 hr) indicated no significant sex-related difference in the number of S phases per 10,000 cells. The DNA content of regenerating versus control livers was comparable in both sexes at t = 22 and 90 hr but higher in females at t = 40 and 65 hr. A possible early postnatal interference of certain hormonal mechanisms in the receptivity to mitotic stimuli is postulated and discussed.
mesh_terms: D000818:Animals; D002364:Caseins / Q000494:pharmacology; D002369:Castration; D004247:DNA / Q000378:metabolism; D005260:Female; D006498:Hepatectomy; D007399:Interphase; D007700:Kinetics; D008099:Liver / Q000166:cytology*; D008297:Male; D008938:Mitosis; D010053:Ovary / Q000502:physiology*; D051381:Rats; D012737:Sex Factors; D013737:Testis / Q000502:physiology*
chemical_list: D002364:Caseins; D004247:DNA