Control of the Sex Characters in the English Sparrow, Passer domesticus (Linnaeus)

Keck, Warren N.

doi:10.3181/00379727-30-6403

Cited by 7 publications

(1 citation statement)

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“…The black pigmentation of the beak of the House Sparrow has long been regarded as an androgen-dependent secondary sexual characteristic, and has even been quoted as a reliable bio-assay technique for the estimation of androgenic hormones (Keck 1932, 1933, 1934, Witschi 1955. However, purified testosterone propionate injected into House Sparrows during the post-refractory period in November failed to cause changes in beak pigmentation.…”

Section: Secondary Sexual Characteristicsmentioning

confidence: 99%

An Investigation of Photo‐refractoriness in the House Sparrow by Artificial Photoperiods

Murton

Westwood

1974

Ibis

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Summary The natural testis cycle and associated changes in bill colour of the House Sparrow Passer domesticus are described. Subjects were wild‐caught at three different times in the breeding cycles:in February when the testes were small and contained only spermatogonia, in May when they were fully recrudesced and contained bunches of spermatozoa and in late July at a time when spontaneous gonad regression was occurring as the birds entered their photo‐refractory phase. Each sample was divided into eight separate groups which were given a range of artificial asymmetric skeleton photo‐periods generalized as LD 6 +1/2:131/2; the 1/2‐h light pulse was given at a different point in the dark period in each group. The birds entrained to skeleton schedules simulating complete photoperiods of up to 12 h duration as if the start of the long light pulse was dawn. However, with long‐day simulations (e.g. 6L 111/2 D 1/2 L 6D which simulates an 18 h photoperiod) the birds entrained to the start of the short light pulse to give an effective photoperiod of 121/2 h (that is, 1/2L 6D 6L 111/2D). The skeleton schedules simulating 14 h and 16 h were interpreted as such in February and were not effective in causing testicular induction, but they were apparently read as days of 161/2 h and 141/2 h in May, and as such maintained active spermatogenesis. The differences are discussed in terms of the changed frequency of a circadian oscillator. When birds captured in July were held on the various skeleton light schedules refractoriness was ended for most the subjects, as was proved by subsequently exposing them to a complete 16‐h photoperiod. Exceptions were the birds in the group given the 14‐h simulation, for these entrained as they had in May and so were effectively receiving a long 161/2‐h day. The discussion presents evidence to show that photoperiods in excess of 14 h cause the light sensitive phase of a circadian oscillator responsible for luteinizing hormone secretion to be phased into the non‐inductive period of darkness. Rehabilitation of the interstitial components of the testis is apparently inhibited in such circumstances.

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Section: Secondary Sexual Characteristicsmentioning

confidence: 99%