20reproA

Chapter 20: 

Chapter 20 Reproduction

Lecture map: 

Lecture map Genetics Development of sex organs Endocrine regulation Female reproductive structures Male reproductive structures

Lecture map: 

Lecture map Lecture two: Cycles Sexual responses Contraception Fertilization Pregnancy Development Parturition Lactation

Slide4: 

Genetics

Genetics: 

Genetics Gregor Mendel Worked with sweet pea Figured all this out without knowing about cells, DNA, chromosomes, evolution! Was unappreciated by peers: too much math! Darwin ALMOST saw his paper…!

Genetics: 

Genetics Alleles—Different versions of a gene “Flower color” is a gene; “Purple” is one flower-color allele “White” is another flower-color allele A trait coded by one gene can have many alleles.

Genetics: 

Genetics Homozygous—both alleles same Heterozygous— two different alleles

Genetics: 

Genetics Dominant— allele that is seen in phenotype of heterozygote. Recessive—allele that is masked in heterozygote. Incomplete dominance—heterozygote displays intermediate trait

Genetics: 

Genetics Often use initial letter of dominant allele Capital letter represents dominant Lower case of same letter represents recessive If “purple” flower is dominant to “white” “P” represents allele for purple “p” represents allele for white

Genetics: 

Genetics Phenotype: what one can observe. Purple flowers White flowers Genotype: what the genes are. White flowers / White flowers White flowers / Purple flowers Purple flowers / Purple flowers

Genetics: 

Genetics Genotypes PP = homozygous Pp or pP = heterozygous pp = homozygous Phenotype which results from genotype: PP = purple flower Pp = purple flower pP = purple flower pp = white flower

Genetics: 

Genetics If you know the phenotype, do you know the genotype? If you know the genotype, do you know the phenotype?

Genetics: 

Genetics Geneticist Reginald Punnett Punnett squares list only genes of interest List sperm genotypes across top List egg genotypes down side Fill in boxes with zygote genotypes

Slide14: 

P p Genetics Eggs of Heterozygous Plant Pollen of Heterozygous Plant P p p P P p P P p p

Slide15: 

P p Genetics Eggs of Heterozygous Plant Pollen of Heterozygous Plant P p p P P p P P p p

Genetics: 

Genetics P p Eggs of Heterozygous Plant Pollen of Heterozygous Plant P p p P P p P P p p

Slide17: 

Dihybrid Cross: SsYy X SsYy SY Sy sY sy SsYy Parent Self-fertilizes 1 4 1 4 1 4 1 4 SY Sy sY sy 1 4 1 4 1 4 1 4 Eggs Sperm 1 16 1 16 1 16 1 16 1 16 1 16 1 16 1 16 1 16 1 16 1 16 1 16 1 16 1 16 1 16 1 16 SSYY SSYy SsYY SsYy SSyY SSyy SsyY Ssyy sSYY sSYy ssYY ssYy sSyY sSyy ssyY ssyy

Slide18: 

AB Ab aB ab AB Ab aB ab Eye Color EGGS SPERM Mother AaBb Father AaBb AABB AABb AaBB AaBb black dark brown dark brown light brown

Slide19: 

LINKAGE If two genes are located close to each other on a chromosome, it is likely that they will sort together during meiosis and their traits will appear linked. If the locus of two genes is far apart, they have a greater chance of sorting independantly during recombination in meiosis. This is a powerful genetic tool. It helps “find” genes, such as one of the breast cancer genes. Genetics

Slide20: 

How to Read Pedigrees = male = female = parents or = individual who shows the trait or = heterozygous carrier of trait = offspring 1 2 3 I, II, III, IV, or V = generation

Slide21: 

A Recessive (inbred!) Pedigree

Genetics: 

Genetics Hybrid vigor

Gender: 

Gender Each human: 22 autosomes 2 sex chromosomes gender of zygote determined by fertilizing sperm.

Gender: 

Gender

Slide25: 

Gender

Slide26: 

Gender Sex-linked traits: men have only one X even a recessive trait on X will be expressed more often shows up in men, transmitted through mother e.g.: baldness, color-blindness

Slide27: 

Imprinting- which parent donated the chromosome affects expression of a gene! sheep with “golden rear end” Epigenetics- chromosome shape http://www.sciencemag.org/feature/plus/sfg/resources/res_epigenetics.shtml Genetics

Slide28: 

Development

Development : 

Development Gonads Testis-determining factor (TDF) from SRY gene on Y chromosome A) “default” -> ovaries B) if TDF -> testes Testes earlier in dev.; ovaries later Note: estrogen filled environment!

Development: 

Development Accessory sex organs A) mullerian ducts -> uterus, fallopian tubes B) leydig cells of testis -> testosterone (first trimester) -> wolffian ducts -> accessory sex organs (epididymis, vas deferens, seminal vesicles, ejaculatory duct) sertoli cells of testis -> MIF (müllerian inhibition factor) -> degenerate mullerian ducts

Development: 

Development External genitalia Various (urethral fold, labioscrotal swelling) -> A) -> vagina, labia, clitoris B) if testosterone -> penis, prostate, scrotum

Development: 

Development

Rare, unusual development: 

Rare, unusual development Hermaphroditism: Both ovarian and testicular tissue is present in the body. Pseudohermaphrodite: Individual with either testes or ovaries and mixed sex characteristics (from a little later in development)

Continued development: 

Continued development Puberty: more GnRH from hypothalamus less sensitivity to negative feedback of testosterone and estradiol -> more FSH and LH during sleep -> more testosterone or estradiol -> secondary sex characteristics (menarche, growth then sealing of bones, etc.)

Continued development: 

Continued development Onset of puberty: exercise, body fat Leptin from adipocytes? (also a satiety factor!) females: generally earlier melatonin from pineal gland?

Further development: 

Further development Menopause: cessation of menses Only estrogen is estrone from adipose tissue (from DHEA, etc. from adrenal cortex) osteoporosis, cardiovascular, hot flashes, vaginal lubrication HRT (hormone replacement therapy)?!

Further development: 

Further development Andropause? Gradual decrease of testosterone, but not GnRH. Note: males have ~ constant levels of LH and FSH as adults.

Slide38: 

Endocrine regulation

Endocrine Regulation: 

Endocrine Regulation GnRH (gonadotropin releasing hormone) from hypothalamus Gonadotropins: LH (luteinizing hormone). FSH (follicle-stimulating hormone). from anterior pituitary Secreted in pulsatile fashion to prevent desensitization and down regulation of receptors.

Endocrine Regulation: 

Endocrine Regulation In womyn: Menstrual cycle! In men: FSH -> Sertoli cells -> spermatogenesis LH -> Leydig cells -> testosterone Maintenance of gonadal structure.

Endocrine Regulation: 

Endocrine Regulation Negative feedback: -l secretion of GnRH. -l secretion of FSH, LH. Female: Estrogen and progesterone. Male: Testosterone. Also: inhibin from both genders -l FSH

Slide42: 

Female Reproductive Structures

Female Reproductive Structures: 

Female Reproductive Structures VULVA!!! Labia majora Labia minora Clitoris

Female Reproductive Structures: 

Female Reproductive Structures Vagina: Cervix Uterus: Perimetrium: Outer layer of connective tissue. Myometrium: Smooth muscle layer. Endometrium: Inner layer of (stratified, squamous, nonkeratinized) epithelium. Shed during menstruation.

Female Reproductive Structures: 

Female Reproductive Structures Fallopian (uterine) tubes: Ova drawn into the tubes by cilia and possible movement of fallopian tubes. Ovaries: large number of follicles which enclose ova.

Female Reproductive Structures: 

Female Reproductive Structures

Female Reproductive Structures: 

Female Reproductive Structures

Womyn’s health: 

Womyn’s health Pap smears (cervical cancer) Endometriosis Cysts Menopause, HRT

Slide49: 

Male Reproductive System

Testosterone: 

Testosterone Testosterone: 5a reductase -> DHT (dihydrotestosterone) DHT is active form in most cells Testosterone may directly affect wolffian duct derivatives (epididymis, vas deferense, ejactulatory duct, seminal vesicles) DHT -> 3a diol, 3b diol

Slide51: 

Testosterone Insert fig. 20.14

Testosterone: 

Testosterone DHT: aromatase in brain-> estradiol 17b -l LH Sertoli and Leydig cells also secrete estradiol. Possible roles: negative feedback in brain. sealing of bones. spermatogenesis. Note: no aromatase -> infertility

Testes: 

Testes Leydig cells also secrete b-endorphin, ACTH, MSH…?! Also paracrine growth factors.

Testes: 

Testes Testes: Seminiferous tubules: Sertoli cells. spermatogenesis Leydig cells: testosterone. Insert fig. 20.12

Testes: 

Testes Seminiferous tubules of testes: Spermatogenesis in concentric circles!

Testes: 

Testes Insert 20.16

Testes: 

Testes Spermatogenesis: Spermatogonia (mitosis) -> primary spermatocytes -> meiosis -> secondary spermatocytes -> spermatids (n, arrested) Note: arrested at primary spermatocyte stage until puberty.

Testes: 

Testes Spermiogenesis: Sertoli cells phagocytose the cytoplasm of spermatids -> spermatozoa (n, still arrested)

Testes: 

Testes Sertoli cells: - Form blood-testes barrier: Prevents autoimmune destruction of sperm which may have new MHC, due to recombination during meiosis! Produce FAS ligand -> binds to the FAS receptor on T cells -> apoptosis - Surround, nourish spermatogonia, etc. - FSH -> Sertoli -> spermatogenesis - spermiogenesis

Men’s health: 

Men’s health Prostate cancer: PSA test Circumcision Fertility lower sperm counts (environmental causes? Frogs in florida?) Sperm motility