02432naa a2200469 a 450000100080000000500110000800800410001902400270006010000160008724500750010326000090017852011940018765000180138165000090139965000180140865000220142665000200144865000280146865000170149665000170151365000100153065000160154065000190155665000140157565000180158965000110160765000100161865000170162865000170164565300260166265300160168865300250170465300260172965300110175565300200176665300100178665300280179665300210182470000190184570000190186477300790188315201322023-05-11       1978    bl uuuu     u00u1 u    #d7 a10.1071/bi97802672DOI1 aTASSELL, R.  aGonadotrophin levels and ovarian development in the neonatal ewe lamb.  c1978  aAbstract: Ovarian weight has been shown to increase markedly in the newborn ewe lamb, and factors which might contribute to this growth were examined. Follicle development was studied in the ovaries of 28 lambs aged 0, 2, 4, 6, 8 and 10 weeks. Plasma samples, pituitaries and one ovary were assayed for gonadotrophin or steroid hormone content. No significant differences between age groups were found in pituitary LH concentration or mean plasma LH. Pituitary FSH concentration increased with age, except for a small decrease at 8 weeks, but no significant changes were seen in plasma FSH. Ovarian progesterone and oestradiol concentrations did not appear to be associated with follicular development. Growing follicles were most numerous at 2 weeks whilst total vesicular follicles reached a peak at 4 weeks. Most vesicular follicles were less than 1.4 mm in diameter. Advanced atresia in vesicular follicles became apparent by 4 weeks although early signs were present in younger lambs. Fluctuations in gonadotrophin levels do not appear to be responsible for variations in number and size of vesicular and growing follicles in the lamb ovary. Other possible explanations are discussed.  aEndocrinology  aEwes  aGonadotropins  aOvarian follicles  aPituitary gland  aPituitary gonadotropins  aProgesterone  aReproduction  aSheep  aCrescimento  aEndocrinologia  aEstradiol  aGonadotrofina  aOvelha  aOvino  aProgesterona  aReprodução  aAnalysis progesterone  aFisiiologia  aFolículos ovarianos  aGlândula pituitária  aGrowth  aNewborn animals  aOvary  aOvary culture (animals)  aOvino Reproducao1 aCHAMLEY, W. A.1 aKENNEDY, J. P.  tAustralian Journal of Biology Sciencegv. 31, n. 3, p. 267-273, Jun. 1978.