Bio - ANIMAL RERODUCTION • Intro 1 Asexual Reproduction...

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Unformatted text preview: ANIMAL RERODUCTION • Intro 1. Asexual Reproduction : No fusion of sex cells(gametes) Budding – part of the parent body separates or fragmentation (parent body breaks apart and the different parts regenerate) Mitotic divisions give rise to clones Have the same genetic constitution of the parent Parthenogenesis – “Virgin Birth” • Females produce eggs (usually by meiosis) which develop w/o fertilization by the male • Some fish or reptiles are parthenogenetic • Evidence that parthenogenetic vertebrates arise as Inter- specific hybrids- Reproduction in Honey Bees • Queens(2n) produce eggs by meiosis • Workers (females, 2n) develop from fertilized eggs(can’t reproduce) • Drones (males, n) develop from unfertilized eggs and produce sperm by mitosis 2. Sexual Reproduction : Union or fusion of gametes Real sponges are Hermaphrodites • Produced both eggs and sperms “Hermes and Aphrodite” Nudibranchs (sea slugs) are cross fertilizing hermaphrodites Hermaphrodites have sexual reproduction Evolution and Sexual Reproduction • Most common form in animals • Some organism can reproduce both ways o Good Conditions – Asexual o Poor or Changing Conditions – Sexual Co-Evolution • Sometimes evolutionary “arms race” between • Mammalian Reproduction 1. Development Indifferent Gonads – can’t tell at early stage • Testes – produce androgens and testosterone o Determining genes on Y • Ovaries Development of Internal Gonads • 2 Complete sets of paired ducts – male and female o One degenerates in the female and the other degenerates in the male Development of External Genitalia • Genital Tubercle o High Level of Testosterone – Penis o Very Low Level of Testosterone – Clitoris o Penis and Clitoris – homologous structures How to define Gender? • Chromosomal Sex – XX an XY • Genetic Sex – can override chromosomal sex • Phenotypic Sex – internal genitalia and external genitalia • Psychological Identification 2. Female Internal Anatomy • Ovaries o Produce steroid sex hormones – estradiol and progestrone o Produce gametes(eggs) – released into the pelvic cavity and then picked up by the oviduct Fertilization occurs in the 1 st 1/3 of the oviduct o Size of an almond • Endometrium o Inner most layer of the uterus. Shed during a period o Where the egg will embed itself into • Uterus o Size of an inverted pear o Two layers Smooth Muscle Endometrium • Vagina o Extends from the uterus to the opening of the exterior of the body o Receives sperm and part of the birth canal • Cervix o Has a cervical opening – very small o Btwn. the Vagina and the endometirum, extends into the vagina, narrow, plugged by mucus Oogenesis – egg production • Ovary has many capsules – Follicles o Oogonia – cells developed when female is a fetus through mitosis o One cell is a potential egg cell • When puberty period begins at each menstrual cycle atleast one...
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Bio - ANIMAL RERODUCTION • Intro 1 Asexual Reproduction...

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