Photoperiodic variation of Leydig cell numbers in the testis of the golden hamster: A possible mechanism for their renewal during recrudescence

Matthew P. Hardy, S. M.L.C. Mendis‐Handagama, Barry R. Zirkin, Larry L. Ewing

Research output: Contribution to journalArticlepeer-review

Abstract

Golden hamster testes regress after short day exposure. The present study asks: 1) are Leydig cell numbers depleted during short days, and 2) if so, how are they replenished during recrudescence. Control hamsters were shown 14 h of light and 10 h of dark (LD 14:10) for 10 weeks (n = 12). Testicular regression was induced by LD 6:18 for 10 weeks (n = 4), and recrudescence by switching regressed hamsters to LD 14:10 for 3 and 5 weeks (n = 8 for each group). All hamsters were injected with [3H]thymidine [3 μCi/gm body wt., intraperitoneally (i.p.)] 1 h or 2 weeks before sacrifice. Leydig cell number per testis was determined by stereological analysis of sections of perfusion‐fixed testes, and labeling indices were determined by autoradiography. Leydig cell numbers were reduced significantly from 18.2 × 106 in control to 9.0 × 106 in regressed testes (p < 0.05); then increased to 14.0 × 106 and 17.9 × 106 in 3‐ and 5‐week recrudesced hamsters. The labeling index was nondetectable (n.d.) for regressed hamsters. In control and recrudescing hamsters the labeling index was measured at two times (t1 = 1 h vs. t2 = 2 weeks post‐injection): in controls, t1 = 0.22 ± 0.15% (mean ± SEM) vs. t2 = 0.28 ± 0.22%; in 1 week recrudesced, n.d. vs. 1.92 ± 0.77% (p < 0.05); at 3 wk, n.d. vs. 4.58 ± 1.74% (p < 0.05); at 5 weeks, 1.92 ± 0.61% vs. 2.25 ± 0.59%. These results are indicative of the existence of interstitial precursor cells that divide, then differentiate, and thus replenish the Leydig cell population during testicular recrudescence.

Original languageEnglish (US)
Pages (from-to)269-276
Number of pages8
JournalJournal of Experimental Zoology
Volume244
Issue number2
DOIs
StatePublished - Nov 1987

ASJC Scopus subject areas

  • Animal Science and Zoology

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