IV-3. Gonads secrete Sex SteroidsSpecies HomeostasisProduction of gametes, Egg + Sperm Fertilization: zygote Development: sex differentiation Birth and development of a childPubertal changesSexually active adulthoodAgingPrimary reproductive organs (gonads: ovaries in female and testes in male): site of gametogenesisand steroid hormone productionAccessory reproductive organs(duct systems and related secretory glands): gamete transport or storage.Secondary sex characteristics: external differences between males and females: hair distribution, body-shape, etcMeiosis produces haploid gametes. Non-disjunction (uneven separation of chromosomes) generates a gamete with abnormal chromosome numbers.FEMALEMITOSISSTAGE OF CELL DIVISIONGerm cell proliferation46 chromosomesper cell (only twoshown here)OögoniumryoMALEEmbryoSpermatogoniumP bertctive adult46 (diploid)SisterchromatidsMEIOSISDNA replicates but no cell division occurs. 2 sets of 46chromosomesFirst meiotic divisionPrimary gamete divides into two secondary gametes. 23 chromosomes duplicatedEmbrPrimaryoocyteSecondary oocyte(egg)FirstPolar bodySisterchromatidsReproductive adultSecondaryspermatocytePrimaryspermatocytePubertyPubertyDisintegratesSecond meiotic divisionSecondary gamete divides.23 chromosomes (haploid)Second polar body disintegrates.ZygoteReproducEgg released from ovary at ovulation.One primary oocyteyields 1 egg.FERTILIZATIONUnfertilized egg passesout of body.SpermatidsSpermOne primary spermatocyteyields 4 sperm.develop intoSperm binding to the egg membrane causes meiotic completion and formation of zygote nn2x n2n
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