Human reproduction

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  • Seminiferous tubules to rete testes to vasa efferentia to epididymis( head, body tail) to vas deferens
  • Human reproduction

    1. 1. Human Reproduction
    2. 2. REPRODUCTIVE EVENTS Humans sexual reproduction, viviparous, unisexual. Each sex has pair of gonads, reproductive duct and accessory structures. Sex organs – Testis( paired) male , ovaries (paired) Gamete formation, hormones Puberty, difference male, female reproductive events 1. Gametogenesis - formation of gametes (sperms/ ova) 2. 3. 4. 5. 6. Insemination -- transfer of sperms into the female genital tract Fertilisation -- fusion of male and female gametes leading to formation of zygote Implantation -- development of blastocyst and its attachment to the uterine wall Gestation -- embryonic development ( from conception to birth ) Parturition-- delivery of the baby ( child birth )
    3. 3. Male reproductive system
    4. 4.  a pair of testes ( in scrotum)  accessory ducts, glands (rete testis, vasa efferentia epididymis, vas deferens external genitalia. (Penis) 
    5. 5. Testi s Paired male gonads- sperm harmones production , oval in shape, length- 4 to 5 cm, a width 2 to 3 cm, 3 cm thick  situated outside the abdominal cavity within a pouch called scrotum.  Scrotum - low temp. of the testes (2–2.5o C lower than the normal internal body temperature) – spermatogenesis  testis is covered by a dense covering capsule tunica albuginea – inside as septae  In each testis -250 compartments called testicular lobules Each lobule -1-3 convoluted seminiferous tubule 
    6. 6. Seminiferous tubule - sperm production lined on its inside by two types of cells  male germ cells (spermatogonia) - meiotic divisions - sperm formation  Sertoli cells (supporting cells) -- provide nutrition to the germ cell -- harmone Inhibin and ABP –Androgen Binding Protein  Interstitial spaces - The regions outside the seminiferous tubules called  interstitial spaces, contain small blood vessels & interstitial cells Leydig cells - male hormone secretion Androgen ( testosterone) 
    7. 7. Accessory ducts, glands (rete testis vasa efferentia epididymis, vas deferens
    8. 8. Vas deferens in abdomen over urinary bladder join seminal vesicle from both sidesejaculatory duct Ejaculatory duct ejaculatory ducts pass prostate gland open into urethra – common passage urethra opens urethral meatus
    9. 9. Penis      External copulatory organ – external genitalia 3 cylindrical masses2 dorsolateral 1 mid ventral Erectile, blood tissue present Enlarge distal end glans penis Loose fitting skin prepuce or foreskin
    10. 10. Accessory Glands Seminal vesicles Between urinary bladder and rectum Alkaline mucoid fluid rich in fructose , ascorbic acid Prostate glands Largest male gland, milky fluid 1/3 volume of semen Helps in sperm motility, maintains pH – survival of sperms Cowper’s glands/ Bulbourethral glands Fluid lubricating passage for sperms Seminal plasma- secretion of all the accessory glands. Rich in fructose, calciu and certain enzymes. Semen – mixture of spermatozoa and seminal plasma. Single ejaculation 200-300 million sperms, slightly alkaline, neutralize acidity in vagina, sperms are protected.
    11. 11. Female reproductive system Sectional view through pelvis
    12. 12.  a pair of ovaries  a pair of oviducts, uterus, cervix, vagina and the external genitalia  oviducts, uterus, vagina - accessory ducts  a pair of the mammary glands ( nourishment of offspring)  All parts are integrated structurally and functionally to support the processes of ovulation, fertilisation, pregnancy, birth and child care.
    13. 13. Here is the gross appearance of a normal uterus with fundus, lower uterine segment, cervix, vaginal cuff, right fallopian tube, left fallopian tube, right ovary, and left ovary from a young woman.
    14. 14. Ovarie s       They are pearl-colored, oblong, walnut-size , on either side of vertebral column. Length of 2 to 4 cm They are attached to the uterus ( double fold mesovarium) and abdominal wall by ligaments. produce female sex hormones (estrogen and progesterone) and male sex hormones, the ovaries produce and release eggs. Each ovary is covered by a thin germinal epithelium which encloses the ovarian stroma. The stroma is divided into two zones – a peripheral cortex and an inner medulla. The developing egg cells (oocytes) are contained in fluid-filled cavities (follicles) in the wall of the ovaries. Each follicle contains one oocyte.
    15. 15. T.S of Ovaries Developing follicles in different Stages  Primary follicle develops into Graafian follicle with mature ovum,  One matures around 14th day of menstrual cycle and ruptures to release the oocyte – Ovulation  After release – follicle filled with blood clot and then yellow cells – called corpus leuteum ( progesteron) 
    16. 16. Accessory ducts - Oviduct, Uterus, Vagina  Oviduct / Fallopian tube- 10-12 cm length, from periphery of each ovary to uterus  Twds ovary funnel shaped infundibulum – edge finger like projections Fimbriae. ( collectin of ovule after ovulation), wider ampulla.  Isthemuss has narrow lumen and joins uterus
    17. 17. Uterus /Womb      The uterus - thick-walled, muscular, pear-shaped organ located in the middle of the pelvis, behind the bladder, and in front of the rectum. anchored in position by several ligaments to pelvic walls . ( narrow cervix --Cavity cervical canal) and the main body (corpus). Birth canal = cervical canal + vagina perimetrium Extenal, thin Layers – myometrium Smooth muscular - strong contraction during bith endometrium Inner glandular, cyclic changes- menstrual cycle, The stratum functional of the endometrium sloughs off during menstruation. The deeper stratum basal provides the foundation for rebuilding the stratum funct
    18. 18. External genitalia - mons pubis, labia majora, labia minora, hymen and clitoris Together called vulva. Mons pubis a pad of fatty tissue over the pubic bone, covered with hair during puberty, protects the internal sexual and Reproductive organs  Clitoris- erectile, hooded organ at the upper joining of the labia, a lot of nerve endings, providing sexual pleasure  labia majora - fleshy folds of tissue, surround the vaginal opening.  labia minora – innner folds  Haymen - just inside the opening of the vagina, a mucous membrane. General protection often torn during the first coitus (intercourse) , or it may be so soft and pliable that no tearing occurs.  torn during exercise / sports or insertion of a tampon or diaphragm  the presence or absence of hymen is not a reliable indicator of virginity or sexual experience. 
    19. 19. Mammary glands      Paired, Glandular, variable fats Glandular tissue – mammary lobes cluster of cells – alveoli Alveoli secrete milkstored in lumen Alveoli- mammary tubules – mammary duct Many ducts join to form ampulla- lactiferous duct
    20. 20. GAMETOGENESIS The process of formation of haploid gametes from diploid germ cells in the gonad is called gametogenesis. Sperrmatogenesis : - The process of formation of haploid sperms from diploid spermatogonia by meiosis called gametogenesis.  begins at puberty- increase in the secretion of gonadotropin releasing hormone (GnRH) – Hypothalamus secretes 
    21. 21. Spermatogenesis and harmones (GnRH) gonadotropin releasing hormone Hypothalamic harmone anterior pituitary gland luteinising hormone (LH) Follicle stimulating hormone (FSH) Leydig cells Stimulates synthesis and secretion of androgens Sertoli cells Androgen stimulates spermatogenesis Secretion of factors for spermatogenesis
    22. 22. FSH Gametokinetic factor  Testesteron secondary sexual characters.  Testersteron also reduces (GnRH) gonadotropin releasing hormone  Inhibin- reduces rate of spermatogenesis  Negative feedback 
    23. 23. Spermatogenes is Spermatogoni a (2n) = 46 • inside wall of Seminiferous tubules • Mitotic division , increase in number • Few are called primary spermatocytes • Meiosis , periodically • After first meiotic/ reduction division • Recombination, crossing over • Haploid , genetically similar secondary spermatocytes n = 23 • 2 equal cells • Second meiotic division Spermatids n =23 4 equal cells Spermatids are transformed to sperrmatozoa/ sperm by Spermeiogenesis. Sperm heads embeded in sertoli cells. Released from tubules by spermiation
    24. 24. Structure of Sperm
    25. 25. Structure of Human sperm Plasma membrane envelops entire boby. Part of sperm Details Head • Elongated haploid nucleus • Anterior cap like acrosome • Acrosome has enzymes. It is derived from Golgi complex during division – fertilization of ovum Neck Connecting head and middle piece Middle part • 2 centrioles – proximal ( after fertilization aster and spindle )and distal ( give rise to axoneme – central axis of tail) • Many mitochondria (produce energy for the movement of tail – motility) Tail • Long slender • Vibration 200-300 sperms – one ejaculation 60% mus have mormal shape , size and 4
    26. 26. Ovulation video
    27. 27. OOGENESIS The process of formation of haploid ovum from diploid oogonia cells in the ovary is called oogenesis. This begins at begins at embryonic development. • At birth many million in fetal ovary Oogonia Primary oocyte Primary follicle Secondary follicles • Propahse –I of meiotic division. • Temporary arrested in this stage • Primary oocyte+ granulosa cells • May follicles degenerate before puberty • 60,000 to 80,000 in each ovary • Primary follicles surrounded by granulosa cells
    28. 28. Contnd. Tertiary follicles Secondary oocyte • Secondary follicles – fluid filled cavity – antrum • Theca layer – internal theca and extermnal theca • Primary Oocyte (2n) size increases and first meiotic division – unequal large haploid secondary oocyte+ 1st polar body • Nutrient rich cytoplasm • Polar body divides???? • Tertiary follicles into Graffian follicle • Membrane Zona pellucida Secondary oocyte
    29. 29.  HW difference Spermatogenesis  0ogenesis Gonads when  Where? Seminiferous / follicles???  Yolk/nutrition accumulation  1st 2nd meiotic division – 2nd after ovulation  Sizes of cells formed / end products  No of cells ( sperms / ova formed)  Polar bodies  Transformation??? As in spermiogenesis 
    30. 30. HW Difference between ovum and sperm           Size Shape Covering membranes Cytoplasm Golgi bodies Mitochondria Centrioles Reserved food Movement Life span
    31. 31.  Menstruation is the term given to the periodic discharge of blood, tissue, fluid and mucus from the reproductive organs of sexually mature females. The flow usually lasts from 3 - 6 days each month and is caused by a sudden reduction in the hormones estrogen and progesterone.
    32. 32. MENSTRUATION CHARACTERISTICS Length of menstrual cycle- first day of the last menstrual bleeding to the first day of the next menstruation.  Average Menstrual cycle – 28 days  Average Flow -4-7 days  Dysmenorrhea-abdominal and lower back pain 
    33. 33. Menstrual cycle
    34. 34. Hormones start to do their thing at the onset of puberty, and various types of hormones are involved  These hormones are: Estrogen 1) Promotes the development and maintenance of female reproductive structures (especially the endometrial lining of the uterus), 2) Assists in the control of fluid and electrolyte balance within the body. 3) Prepares the follicle for the release of an egg. Estrogen also has many other functions.
    35. 35. Progesterone:  Secreted at ovulation, helps to prepare the endometrium (womb lining) for the implantation of an egg, prepares mammary galnds for milk production. Primarily concerned with the procreation and survival of the fetus.
    36. 36. FSH Follicle Stimulating Hormone:  Stimulates the follicles (a follicle is a balloon shaped structure which is filled with fluid and contains an egg, follicles are found in the ovaries) to ripen several eggs. At the same time the ovaries release oestrogen.
    37. 37. LH Lutenising hormone:  Further develops the follicles, triggers ovualtion and stimulates production of other hormones necessary for the post ovulatory stage of the menstrual cycle. The secretion of hormones is a complex affair.Various parts of the body become involved in a myriad of chemical transactions.
    38. 38. It is the balance and interplay between these hormones which regulate the specific events that make up the menstrual cycle.  Factors like nutrition, stress, exercise, and belief systems can all influence how the hormones work and what we experience during our cycles. 
    39. 39. Oogenesis and harmones (GnRH) gonadotropin releasing hormone Hypothalamic harmone anterior pituitary gland luteinising hormone (LH) Follicle stimulating hormone (FSH) Ovary , Ovulation Graffian follicle Copus luteum Estrogen, progesterron secretion Negative feedback Growth of follicle Estrogen secretion Negative
    40. 40. Fertilization and implantation Coitus , insemination The motile sperms swim rapidly, pass through the cervix, enter into the uterus and finally reach the junction of the isthmus and ampulla (ampullary-isthmic junction) of the fallopian tube  Ovum after release at this point  Fertilisation - if the ovum and sperms are transported simultaneously to the ampullaryisthmic junction.  The process of fusion of a sperm with an ovum is called fertilisation.  
    41. 41. Fertilization
    42. 42. Fertilization Meiotic division of secondary oocyte after sperm enters plasma membrane of the ovum.  Second meiotic division – second polar body and ovum / ootid  Ovum + Sperm = Zygote  Explain sex determination of a child 
    43. 43. Significance of fertilization Restoration of diploidy  Recombination of genes  Ovum does not have centriole – sperm centriole is introduced  Ovum activation completes division  Gives polarity, development – organ forming areas 
    44. 44. Cleavage, Morula Zygote from oviduct to uterus– mitotic division, first cleavage in first 36 hrs 2,4,8,16 blastomere  Embryo with 8 – 16 cells – Morula  Morula – division continues – hollow ball called Blastocyst.  Fluid filled cavity Inner cell mass/ embryoblast Trophoblast – gets attached with endometrium After attachement, endometrium grows and covers blastocyst, Embeded -Implantation ( in 2-3 days), then pregnancy
    45. 45. MATERNAL ADAPTATION TO PREGNANCY       Terms used to denote Fetal Growth Ovum - From ovulation to fertilization Zygote - From fertilization to implantation Embryo - From implantation to 5-8 weeks Fetus - From 5-8 weeks until term Conceptus - Developing embryo or fetus and placental structures throughout pregnancy.
    46. 46. Pregnanacy chorionic villi – finger like porjections on trophoplast  Villi surrounded by maternal blood, uterine tissues  They develop eventually into placenta  Inner cell mass – ectoderm, mesoderm, endoderm - different organs  Inner mass also have stem cells 
    47. 47. Role of placenta Organic connection between developing foetus and uterine wall of mother- phisiological exchange of substances 1. Transportation of nutrients (aa, monosugars, vitamins etc) 2. Diffusion of gases O2 and CO2 3. Nitrogenous substances transport from foetus to mother 4. Stoarage of glycogen acts as liver before its development.  Support fetal growth -Acts as endocrine gland to secrete harmones like human chorionic gonadotropin (hCG), human placental lactogen (hPL), estrogens, progestogen Relaxin by ovary dialation of uterus during birth.
    48. 48. Parturition foetal ejection reflex.  Oxytocin role 
    49. 49. Lactation
    50. 50. Sexually transmitted diseases(STD) venereal diseases (VD) or reproductive tract infections (RTI) Diseases / infections – transmitted through sexual intercourse  Gonorrhoea, syphilis, genital herpes*, chlamydiasis, genital warts, trichomoniasis, hepatitis-B*, AIDS* (HIV infection)  transmitted by sharing of injection needles, surgical instruments, etc., with infected persons, transfusion of blood, or from an infected mother to the foetus too.  * not curable, others are 
    51. 51. Symptoms Absence or less significant symptoms in the early stages of infection  minor symptoms include itching, fluid discharge, slight pain, swellings, etc., in the genital region  Infected females - asymptomatic hence, may remain undetected for long.  Complications-- pelvic inflammatory diseases  (PID), abortions, still births, ectopic pregnancies, infertility or even cancer  of the reproductive tract. 
    52. 52. Prevention Avoid sex with unknown partners/multiple partners. (ii) Always use condoms during coitus. (iii) In case of doubt, go to a qualified doctor for early detection and get complete treatment if diagnosed with disease. Social – High risk 15-24
    53. 53. Infertility unable to produce children inspite of unprotected sexual co-habitation. – After after 2 years  Reasons for infertility - physical, congenital, diseases, drugs, immunological or even psychological.  Blaming female  Role of infertility clinics  assisted reproductive technologies (ART) 
    54. 54. 1. Test tube baby programme In vitro fertilisationand sperms from ova from the wife/donor (female) the husband/donor (male) are collected. 2. induced to form zygote under simulated conditions in the laboratory. 3. The zygote or early embryos (with upto 8 blastomeres) could then be transferred into the fallopian tube -- ZIFT–zygote intra fallopian transfer OR Embryos with more than 8 blastomeres, into the uterus (IUT – intra uterine transfer) Further development in the uterus Embryos formed by in-vivo fertilisation could be used for such transfer to assist
    55. 55.  Women no ova formed- Transfer of an ovum collected from a donor into the fallopian tube (GIFT – gamete intra fallopian transfer) ,Fertilisation internal  Intra cytoplasmic sperm injection (ICSI) – sperm injected into ovum
    56. 56. Less sperm count / unhealthy sperms artificial insemination (AI) technique  semen collected - from the husband or a healthy donor is artificially introduced either into the vagina or into the uterus (IUI – intra-uterine insemination) of the female. 
    57. 57. Difficulties Requires high precision  specialised professionals  Expensive instrumentation  Facilities in few centre  Affordability   Adoption

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