Spermiogenesis (not a typo)

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Spermiogenesis (not a typo)

• Changes that transform spermatids into
  spermatozoa
• discarding excess cytoplasm and growing tails

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Spermatozoon

• Head is pear-shaped front end
• 4 to 5 microns long structure containing the
  nucleus, acrosome and basal body of the tail
  flagella
• nucleus contains haploid set of chromosomes
• acrosome contains enzymes that penetrate the egg
• basal body

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Spermatozoon

• Tail is divided into 3 regions
• midpiece contains mitochondria around axoneme of
  the flagella (produce ATP for flagellar movement)
• principal piece is axoneme surrounded by fibers
• endpiece is very narrow tip of flagella

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Female repro
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Female Reproductive System

• Produce and deliver gametes
• Provide nutrition and room for fetal development
• Give birth
• Nourish infant

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Sex Differentiation

• Male and female are indistinguishable for first 8
  to 10 weeks of development
• Female develops
• Without testosterone or müllerian-inhibiting
  factor
• The (male) mesonephric duct degenerates
• paramesonephric duct
• develops into uterine tubes, uterus and vagina
• genital tubercle becomes clitoris
• urogenital folds develop into labia minora
• labioscrotal folds into labia majora

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Hormones and Sex Differentiation

• Gonads begin to develop at 6 weeks
• The male and female reproductive systems have
  different embryological origins
• mesonephric ducts develop into male reproductive
  system
• paramesonephric ducts (müllerian ducts) develop
  into female reproductive tract

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Ovary

• Produces eggs and hormones
• almond-shaped, 3 cm x 1.5 cm x 1 cm
• tunica albuginea capsule like on testes
• cortex produces gametes medulla holds vessels
• Each egg develops in its own fluid-filled
  follicle and is released by ovulation
• Ligaments
• attached to uterus by ovarian ligament
• attached to pelvic wall by suspensory ligament
• contains ovarian artery, vein and nerves
• anchored to broad ligament by mesovarium

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Ovary
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Anatomy of Ovary
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Uterine (Fallopian) Tubes

• 10 cm long, muscular tube lined with ciliated
  cells
• Major portions
• narrow isthmus near uterus
• body (ampulla) middle portion
• flares distally into infundibulum with fimbriae
• Enclosed in superior margin of broad ligament
  (mesosalpinx)

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Figure 28.16
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Uterus

• Thick-walled, pear-shaped muscular chamber that
  opens into vagina and tilts forward over urinary
  bladder
• internal and external os of cervical canal
• openings into uterine tubes in two upper corners

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Vagina

• Outer adventitia, middle muscularis and inner
  mucosa
• Epithelium
• child - simple cuboidal
• puberty - estrogens transform to stratified
  squamous
• bacteria ferment glycogen rich cells producing
  acidic pH

• 8-10 cm distensible muscular tube
• allows for discharge of menstrual fluid, receipt
  of penis, semen and birth of baby
• Tilted posteriorly between rectum and urethra
• urethra embedded in its anterior wall

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Secondary Sex Organs

• Internal genitalia
• duct system of uterine tubes, uterus, vagina
• External genitalia
• clitoris, labia minora, and labia majora
• occupy perineum
• accessory glands beneath skin provide lubrication

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Vulva (Pudendum)

• Mons pubis - mound of fat over pubic symphysis
  covered by pubic hair
• Labia majora - thick folds of skin
• Labia minora - medial, thin hairless folds
• form vestibule contains urethral and vaginal
  openings
• form hoodlike prepuce over clitoris
• Clitoris - erectile, sensory organ
• Vestibular bulbs - erectile tissue around vagina
• Greater and lesser vestibular and paraurethral
  glands open into vestibule for lubrication

Lab topic
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Puberty

• Begins at age 9-10 (US)
• Triggered by rising levels of GnRH
• stimulates anterior lobe of pituitary to produce
• follicle-stimulating hormone (FSH)
• luteinizing hormone (LH)
• Follicles develop and begin to secrete estrogen
  and progesterone

• Thelarche - development of breasts
• Pubarche - growth of pubic and axillary hair
  apocrine and sebaceous glands
• Menarche - first menstrual period
• requires at least 17 body fat in teenager, 22
  in adult
• leptin stimulates gonadotropin secretion
• improved nutrition (? body fat) has lowered avg.
  age of onset to 12
• Female hormones secreted cyclically and in
  sequence

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Oogensis and Sexual Cycle

• Reproductive cycle - events occurring between
  fertilization and birth
• Sexual cycle - events recurring every month when
  pregnancy does not occur
• ovarian cycle events in ovaries
• menstrual cycle parallel changes in uterus

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Oogenesis

• Monthly event produces haploid egg by meiosis
• Embryonic development of ovary
• female germ cells arise from yolk sac
• differentiate into oogonia, multiply
• transform into primary oocytes - early meiosis I
• most degenerate (atresia) by childhood
• by puberty 400,000 oocytes remain
• FSH stimulates completion of meiosis I, produces
  secondary oocyte and 1st polar body
• proceeds to meiosis II and ceases until
  fertilization
• after fertilization , releases 2nd polar body

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Sexual Cycle

• Averages 28 days, ranges from 20 to 45
• Hormone cycle hierarchy of control
• hypothalamus? pituitary ? ovaries ? uterus
• Follicular phase (2 weeks)
• menstruation occurs during first 3 to 5 days of
  cycle
• uterus replaces lost endometrium and follicles
  grow
• Luteal phase (2 weeks)
• corpus luteum stimulates endometrial thickening
• endometrium lost without pregnancy

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• The female reproductive cycle is actually two
  cycles in one
• The ovarian cycle controls the growth and release
  of an egg.
• The menstrual cycle prepares the uterus for
  possible implantation of an embryo.

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Ovarian Cycle - Follicular Phase

• Menstruation (day 1) to ovulation(14) (variable)
• Difficult to predict date of ovulation
• Contains menstrual and preovulatory phases

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Ovarian Cycle - Preantral Phase

• Discharge of menstrual fluid (days 1-5)
• Before follicle develops antrum
• primordial and primary follicles

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Ovarian Cycle - Antral Phase

• Day 6 to 14, one dominant follicle advances to
  mature (graafian) follicle secretes estrogen

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Ovarian Cycle - Ovulation

• Mature follicle ruptures, releases oocyte
  influenced by LH
• Egg has only 24 hours to be fertilized or it dies

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Histology of Ovarian Follicles
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Pituitary-Ovarian Axis
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Ovarian Cycle - Luteal Phase

• The second half of the menstrual cycle is
  dominated by the corpus luteum
• Corpus luteum - forms from ruptured follicle,
  under influence of LH secretes progesterone
• Progesterone inhibits FSH and LH secretion

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Menstrual Cycle - Proliferative Phase

• Day 6-14 rebuild endometrial tissue
• mitosis occurs in stratum basalis
• result of estrogen from developing follicles

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Menstrual Cycle - Secretory Phase

• Further thickening of endometrium due to
  secretion and fluid accumulation -- not mitosis
• Due to progesterone stimulation of glands

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Menstrual Cycle Premenstrual Phase

• Involution of corpus luteum, progesterone falls
• spiral arteries constrict causes endometrial
  ischemia
• stratum functionalis sloughs

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Menstrual Cycle - Menstrual Phase

• Blood, serous fluid and endometrial tissue are
  discharged

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Pregnancy and Childbirth

• Gestation (pregnancy)
• lasts an average of 266 days from conception to
  childbirth
• implantation occurs about one week after
  ovulation
• gestational calendar measured from first day of
  the womans last menstrual period (LMP)
• Parturition is the medical term for giving birth
• Birth predicted 280 days from LMP
• 3 three month intervals called trimesters

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Oogenesis - from oocyte to ovum

• Eggs are giant cells
• Egg coat
• Mammals Zona pellucida AND cumulus cells

Polar body