412g Dr. Park-Sarge lecture notes-3 2009

412g Dr. Park-Sarge lecture notes-3 2009 - IV-3 Gonads...

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IV-3. Gonads secrete Sex Steroids Species Homeostasis Production of gametes, Egg + Sperm Fertilization: zygote Development: sex differentiation Birth and development of a child Pubertal changes Sexually active adulthood Aging Primary reproductive organs ( gonads : ovaries in female and testes in male) : site of gametogenesis and steroid hormone production Accessory 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, etc Meiosis produces haploid gametes. Non-disjunction (uneven separation of chromosomes) generates a gamete with abnormal chromosome numbers. FEMALE MITOSIS STAGE OF CELL DIVISION Germ cell proliferation 46 chromosomes per cell (only two shown here) Oögonium ryo MALE Embryo Spermatogonium P bert ctive adult 46 (diploid) Sister chromatids MEIOSIS DNA replicates but no cell division occurs. 2 sets of 46 chromosomes First meiotic division Primary gamete divides into two secondary gametes. 23 chromosomes duplicated Embr Primary oocyte Secondary oocyte (egg) First Polar body Sister chromatids Reproductive adult Secondary spermatocyte Primary spermatocyte Puberty Puberty Disintegrates Second meiotic division Secondary gamete divides. 23 chromosomes (haploid) Second polar body disintegrates. Zygote Reproduc Egg released from ovary at ovulation. One primary oocyte yields 1 egg. FERTILIZATION Unfertilized egg passes out of body. Spermatids Sperm One primary spermatocyte yields 4 sperm. develop into Sperm binding to the egg membrane causes meiotic completion and formation of zygote n n 2x n 2n
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