Development of the male reproductive system and sexual transformation in the nematode Caenorhabditis elegans☆

[摘要] Thesmallfree-livingnematodeCaenorhabditiselegansisusuallyfoundasahermaphrodite,butoccasionallytruemalesappearinthepopulation.Thisstudyprovidesanaccountofgonadogenesisinthenormalmaleandinamutantthatisatemperature-sensitivesextransformer.Maleandhermaphroditegonadsdevelopfrommorphologicallyidenticalprimordia.Thesmallprimordialgonadliesontheventralsideoftheworminthecoelomiccavity.Thegonadialprimordiumcontainsfournucleiatparturition.Asthisprimordiumdevelopsinahermaphrodite,itproducesadouble-armed,mirrorsymmetricalgonadthatproducesfirstspermandtheneggs.Inthemale,however,thisprimordiumdevelopsintoanasymmetricalstructurecomposedofaventrallylocatedtestis,aloopregion,aseminalvesicle,andavasdeferens.Themalegonadpresentsalinearsequenceofnucleiinsuccessivestagesofspermatogenesisbeginningwithamitoticregioninthetestis,followedbyclearlydistinguishablestagesofmeiosisthroughouttheloopregiontotheseminalvesicle.Atemperature-sensitivesextransformermutant,tsB202,hasbeenisolated.tsB202carriesanautosomalrecessivemutationinlinkagegroupIIthatatrestrictivetemperaturetransformsanXXhermaphroditeintoaphenotypicmale,completewithanormalmalegonadandvestigialexternalgenitalia.Thesetransformedmalesareclassifiedaspseudomalesbecausetheydonotexhibitmatingbehavior.Temperatureshiftexperimentshavedeterminedthespecifictemporalsequencesofgonadogenesis,oogenesis,andspermatogenesis.Propermanipulationofthetemperatureregimencausestheproductionofintersexes.Inoneintersex,amalegonadcompletewithsperm,seminalvesicle,andvasdeferensalsocontainsoocytes.Inanotherintersexproducedbythecomplementarytemperatureshift,ahermaphrodite-shapedgonaddevelopsthatproducesonlyspermandnooocytes.

[学科分类] 生物科学（综合）