Fetal mammary gland differentiation in vitro in response to hormones: I. Morphological findings☆

[摘要] Tostudythemorphogeneticdevelopmentofthefetalratmammaryanlagen17daysafterconception,rudimentswereexplantedasorganculturesinWaymouth's-agarmediumfor3,6,and9days.Thecultureswerethenexaminedhistologically,andtheextentofmorphogeneticdevelopmentinducedbythehormoneswhichareknowntoinducedifferentiationinthemammaryglandoftheadultrat,wasratedbyagradingsystemdesignedforthispurpose.Survivaloftheexplantswasgoodthroughtheentirecultureperiod.Insulinimprovedmaintenanceandgrowthintheanlagenoverthehormone-freegroup.Insulinalsoprovedtobearequirementfortheexpressionofthegrowth-promotingactionofprolactin.Insulinplusprolactinsignificantlystimulatedgrowthandsustainedcellmultiplicationafter4daysofculture,resultinginthickductswithterminalcellaccumulations.Aldosteronealoneinducedductuleformationandramification,althoughwiththeadditionofinsulinplusprolactintheabilityofaldosteronetoinducedifferentiationwasfullyexpressed.Thelatterhormonecombinationgavethebestresultswiththeformationofductulescontainingmucinoussecretion.Progesteroneaddedtoinsulinplusprolactinplusaldosteroneincreasedgrowthfurtherandinducedtheappearanceofaprofuse,granularsecretion.Estrogenprovedtohavenopositiveeffectandwastoxicathigherconcentrations.Somatotropinfailedtoreplaceprolactininitsgrowth-promotingaction.Theeffectsofthesehormonesonthemammaryanlagenwereinhibitedbytestosterone.Onthebasisoftheseresultsthefollowingschemeforthedevelopmentofmammaryanlageninvitroisproposed:Insulininducesgrowthandpenetrationoftheanlagenintothemesenchyme.Prolactinstimulatesthisproliferationfurther.Aldosteronecausestheformationofductsandtheirprofuseramification,togetherwithsecretion.Progesteroneenhancesfurthercellmultiplicationandsecretoryactivity.

[学科分类] 生物科学（综合）