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Phase 1 Histology COPY COPY > SUGER > Flashcards

SUGER Flashcards

1
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KIDNEY

  • pale cortex / dark medulla / 10-15 meduallary pyramids
  • cortex contains glomeruli and coils of proximal/distal tubules
  • medulla contains pyramids with straight parts proximaal/distal tubule, loop of Henle, collecting duct

Blood

  1. 5/6 branches renal artery
  2. arcuate arteries at medullary/cortical border (give off vasa recta - deep to medulla)
  3. then interlobular arteries penetrate cortex at regular intervals
  4. affertent to glomerulus
  5. efferent from glomerulus (filtered blood) - thin walled and between tubules
  6. acquire fluid and ions -> drain to arcuate veins -> systemic
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2
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GLOMERULUS

  • blood to glomerulus for filtration
  • passes primary filtrate to nephron for selected reabsorption
  • parallel array of fenestrated capillaries ensheathed by podocytes
  • between loops = mesangiel cells (matrix forming)
  • afferent arteriole wall produces renin
  • next to glomerulus = segment of distal tubule with macula densa
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3
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GLOMERULAR TUFT (PAS)

  • arise from vascular pole of glomerulus = entrance afferent and exit efferent
  • in this angle lies a distal loop of nephron with palisade of macula densa
  • capillary loop surrounded by podocyte
  • surrounded by urinary space - separates glomerulus from bowman’s capsule
  • arrow to distal tubule
  • MACULA DENSA - around blood vessels regulate blood flow, provides framework for glomerulus.
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4
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FILTRATION BARRIER

  • basement membrane
  • synthesised and maintaiend by endothelial capillary cells and epithelial cells (podocytes) that ensheath them
  • endothelial = fenestrated
  • podocytes stand off membrane with foot processes
  • creates physical pores
  • pores guarded by filtration membrane
  • membrane is charged and resists passage of some molecules
  • water and solutes may pass to urinary space = primary filtrate
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5
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PROXIMAL TUBULES (PAS)

  • highly coiled (sometimes with straight projection to medulla)
  • prominent brush border and complex invaginations @ basolateral membrane dark pink
  • extensive reabsorption here
  • Na+ active transport with glucose (cotransporter - GLUT)
  • take up protein and polypeptide by endocytosis
  • cells contain lyzosomes which break down proteins before returning to circulation
  • any small negatively charged protein can enter primary filtrate
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6
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PROXIMAL TUBULES 2 (PAS)

  • this slide - straight portion of proximal tubule
  • leads to loop of Henle
  • if glomeruli present = cortex
  • some project to medulla
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7
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LOOP OF HENLE (PAS)

  • mostly @ medulla
  • thick/straight descending, thin loop, thick ascending
  • thick descend = similar to proximal tubule
  • thick ascend = similar to distal tubule
  • longest thin loop penetrate deepest to medulla when glomerulus = cortico-medulla junction
  • thin descending portion = low permeability to ions and urea, high permeability to water
  • thin ascending portion retains water, reabsorption Na+ and Cl-
  • this produces dilute/hypotonic filtrate but a hypertonic interstitium
  • vasa recta (straight capillaries) run alongside tubules

this slide - thick and thin limbs and vasa recta

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8
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DISTAL TUBULE (PAS)

  • from medulla to cortex then to vascular pole of glomerulus
  • macula densa here monitors sodium levels to influence intitial filtration of glomerulus
  • paler than proximal
  • deep invaginations of basal plasma membrane with numerous mitochondria
  • mitochondria indicative of control acid/base balance and concentration of urine (ATP)
  • with aldosterone sodium reabsorbed, potassium excreted
  • bicarbonate ions reabsorbed, hydrogen excreted - acidic urine

@ cortex both proximal and distal tubules present

proximal more tightly coiled therefore appear to be more numerous

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9
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COLLECTING DUCTS (PAS)

  • pale cuboidal cells
  • wide lumen
  • starts at cortex, filtrate to collecting tubules than larger ducts
  • collecting tubules from many nephrons coalesce to larger ducts and form visible streaks - medullary rays
  • few organelles
  • collecting tubules - dark intercalated cells with high mitochondria
  • surrounded by hypertonic medium interstitial from loop of Henle
  • ADH increases permeability to water (concentrates urine)

prone to kidney stones and infection

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10
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JUXTAGLOMERULAR APPARATUS (PAS)

  • afferent/efferent arterioles, macula densa, lacis cells
  • afferent - cells produce renin - granules in cytoplasm
  • renin catalyses angiotensin 1 (liver) -> angiotensin 2 (conversion at lungs) -> aldosterone release by suprarenal cortex -> reabsorption of sodium and water @ distal tubules and collecting ducts
  • lacis cells and macula densa regulate renin secretion by monitoring sodium levels

this slide - obvious macula densa

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11
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UROTHELIUM

  • ureters, bladder and most urethra
  • pseudo-stratified epithelium
  • surface cells adapted to withstand prolonged urine exposure
  • 3-8 layers (distension dependent)
  • basal cells = cuboidal
  • above = columnar (relaxed)
  • surface = large, binucleate umbrella cells

umbrella cells:

  1. thickened membrane plates joined by thin membrane bands
  2. lipid composition (unique)
  3. relaxed plated = perpendicular to membrane
  4. stretched = drawn to surface of cell
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12
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URETER

  • epithelial tube with 2 helical layers of smooth muscle
  • star shaped lumen
  • towards bladder = longitudinal smooth muscle
  • 3 constrictions (kidney stones will lodge here)
    1. origin (pelvis of kidney)
    2. at sacro-iliac joint (passes to true pelvis)
    3. as enters postero-inferior bladder surface
  • reflux prevented by compression of ureter by muscular wall bladder
  • contains blood vessels and adipose
  • smooth muscle for peristaltic contraction
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13
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URINARY BLADDER

  • wall = thick bundles of smooth muscle with no preferred direction except neck = 3 distinct layers
    1. innermost = longitudinal projects inferiorly and turns transversely to form a sphincter around prostatic urethre (male) and external meatus (female)

thrown into folds w/ umbrella cells

walls of bladder contains small nerves (autonomic)

sympathetic NS = mainly blood vessels at bladder

inset = nerves

micturition

when external sphincter relaxes (sympathetic) and muscle wall (detrusor) contracts (para)

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14
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PROSTATIC URETHRA

  • urethra longer in males
  1. prostatic
  2. membranous
  3. bulbous
  4. pendulous
  • urothelium (pseudo-stratified columnar) except at distal end
  • mucus glands along length
  • distal urethra = stratified squamous (male and female)
  • both sexes = striated (voluntary) muscle sphincter from muscles of pelvic diaphragm around membranous part
  • under prostatic urothelium = dense fibrous connective tissue to prevent distension

inset = U-shaped prostatic urethra

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15
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TESTES

  • within collagenous capsule = tunica albuginea
  • within fibrous septa to 250 lobules (each lobule with up to 4 germ cell producing semniferous (tubules)
  • semniferous tubule = 50cm loop (open both ends)
  • drain to rete testes (channels)
  • Leydig cells between semniferous tubules
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16
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SEMNIFEROUS TUBULE

  • stratified epithelium with support (sertoli) and germ line (developing spermatazoa)
  • at periphery = germinal epithelial
  • GE produces large cells with speckled chromatin = spermatagonis
  • spermatogonia develop to spermatocytes
  • spermatocytes pass blood testis barrier created by Sertoli
  • Sertoli = blood testis barrier and nurture sperm
  • production = 64 days
  • maturation wave passes slowly down each tubule
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17
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SEMNIFEROUS TUBULES

  • thin fibrous capsule
  • closest to membrane = germinal epithelium with spermatogonia (speckled)
  • between cells are smaller primary spermatocytes and Sertoli cells (pale irregular nuclei)
  • towards centre depends on stage in cycle
  • sometimes primary/secondary spermatocytes (small dense nuclei)
  • otherms more mature (narrow and elongated heads)
  • between tubules = leydig clumps

arrow to spermatid

reduction division (2n-1n -> first meiotic) takes place when primary to secondary @ luminal side of blood testis barrier i.e. not in contact with blood stream

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18
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EPIDIDYMIS

  • rete testis = cuboidal ep
  • rete testis to efferent ductules (similar)
  • epididymis = single 5m coiled tube
  • thick fibrous capsule attached to mediastinum of testes posteriorly - storage and maturation site for sperm aggregated within lumen
  • tall pseudo-stratified columnar ep
  • small rounded basal cells support tall columnar with microvilli (stereocilia)
  • stereocilia (non-motile) reabsorb seminal fluid, phagocytose damaged sperm and cell debris. also nutrients for sperm
  • thin layer of smooth muscle thicker as approaches vas
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19
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VAS DEFERENS

  • spirally arranged smooth muscle
  • similar to epididymis but shorter cells and microvilli
  • sometimes has longitudinal folds - lamina propria
  • sudden and rhythmical contraction expels sperm

thick muscular wall makes vas feel cord like

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20
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SEMINAL VESICLE

  • highly coiled glands at postero inferior bladder
  • double layered capsule of smooth muscle
  • long narrow folds
  • stimulated by testosterone - enlarge and secrete creamy opalescent fluid with acid pH. rich in globulin, vitamin C, amino acids and sugars
  • contraction of smoooth muscle mixes with spermatozoa
  • simple columnar epithelium
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21
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PROSTATE

  • 50 branched tubular glands
  • smooth muscle matrix
  • smooth muscle capsule around all
  • 3 layers (concentric) of glands - mucosal - submucosal - main
  • @ ejaculation, contract and mix secretions @ ejaculatory duct
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22
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PROSTATIC EPITHELIUM

  • glands varied - straight, coiled, branched
  • epithelium thrown into broad, branching folds
  • with testosterone, cells increase in height and secrete digestive enzymes - acid phosphatase (major component of seminal fluid) - (PSA) prostate specific antigen
  • lumen often with sec product / calcified glycoprotein
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23
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PROSTATE 2

  • this slide L - skeletal muscle at underside of prostate - pelvic diaphragm with levator ani
  • this slide R - spiral tubular gland at submucosal level
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24
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PENILE URETHRA

  • prostatic, membranous, penile
  • membranous and penile = non-secreting pseudostratified columnar
  • at distal end = stratified squamous epithelium (within glans)
  • bulbo-urethral glands within membranous urethra produce watery galactose rich secretion, precedes main ejaculate - can sometimes be a problem with catheterisation
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25
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PENIS

  • erectile compartments = large endothelium lined blood vessels supported by connective tissue
  • each surrounded by compact collagen layer = tunica albuginea
  • helicine branches of pudendal artery
  • when flaccid arteries transmit very little blood due to artero-venous shunts
  • para. stimulus shut shunts (point and shoot)
  • most skin = hairy, loosely attached to columns - except prepuce and glans (non-kerat)
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26
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VAGINA

  • stratified squamous thinly keratinised at vulval end
  • thin pre-puberty and post menopause
  • beneath epithelium = lamina propria with small blood vessels (moisture by diffusion)
  • surrounding epithelium = fibro muschular tube with collagen/elastic and smooth muscle
  • sphincter of skeletal muscle at lower end
  • bartholin glands - mucus posterolaterally at lower end of vagina
  • with age = weaker fibro-muscular tube
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27
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EPITHELIAL SQUAMES

  • in menstrual cycle surface cells accumulate glycogen and flake off
  • desquamated cells rupture and bacteria generate lactic acid
  • low pH at vagina

pale green cells - outermost layer, predominate at first half of menstrual cycle

pink cells - deeper layer

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28
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CERVIS

  • protrudes to anterior wall vagina
  • surrounded by gulley - lateral, anterior, posterior ornices
  • outer surface - SSNKE (identical to vagina)
  • cervical canal (between internal and external os) = tall columnar epithelium thrown into deep gland-like folds
  • stroma = fibrous connective and smooth muscle
  • this slide - external os
29
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CERVICAL LINING

  • secretes mucus - consitency of which varies throughout menstrual cycle
  • first half - thin and watery
  • second half - viscous after ovulation as plug to prevent microorganism entry
  • transitional zone - between sensitive cervical lining and other stratified squamous epithelium prone to infection and lesion
  • this slide - mucus glands visible
30
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UTERINE BODY

  • 3 poorly defined layers myometrium smooth muscle
  • lined by epithelial endometrium
  • myometrium hormonally sensitive

hyperplasia and hypertrophy @ pregnancy

large arteries and veins between inner and middle layers, also supply endometrium and give rise to spiral arteries (significant @ menstruation)

31
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ENDOMETRIUM

  • uterus = simple columnar with tubular glands

PROLIFERATIVE PHASE - first half, stroma tickens and length glands increase

SECRETORY PHASE - second half of menstrual cycle - glands secrete and stroma differentitates to environment for ovum

MENSTRUATION - most endometrium shef leadving only bases of glands - MENSES = 4 days

32
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PROLIFERATIVE ENDOMETRIUM

  • post menses
  • 10 days, regrow glands stroma and blood vessels
  • at end of proliferation = ovulation, then secretory
  • TUBULAR GLANDS APPEAR STRAIGHT and cells do not secrete endometrial mucus
  • stroma compact
  • uncoiled arteries and veins
  • mitotically dividing cells within glands and stroma
  • simple glands (often circular)
  • loose connective tissue
33
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SECRETORY ENDOMETRIUM

  • ovulation @ day 14-16
  • cells have large vacuole of glycogen below nuclei
  • from these stores syntehsise mucins
  • glands = irregular / sacculated with secretions @ lumen
  • stroma oedematous
  • arteries lengthen and become spiral
  • @ end (late phase) spiral arteries close down and blood leaks to stroma = anoxia therfoer decidua detaches and menses begins
34
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UTERINE TUBES

  • 10 cm within broad ligament
  • 4 regions:
    1. intramural
    2. short narrow isthmus
    3. long ampulla
    4. wide infundibulum (with fimbria)
  • lumen varies in appearance
  • UTERINE = star-shaped
  • INFUNDIBULUM = complex folds and wide
  • ciliated - cilia become longer and beat more strongly soon after ovulation
35
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UTERINE TUBE EPITHELIUM

  • two helical layers of smooth muscle (inner circular) and outer (longitudinal)
  • simple columnar epithelium - ciliated and mucous secreting
  • epithelium is hormonally-sensitive - cels taller and cilia beat more strongly around ovulation
  • also secretions are thinner and more copioius at this time
  1. fertilised at ampulla
  2. ectopic pregnancy at uterine tube
  3. surrounded by broad ligament and mesovarium connecting ovary and broad ligament
36
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OVARY

  • surface = germinal epithelium (thick BM)
  • attached by mesovarium mesentery to upper posterior surface of broad ligament (continuous with ovary)
  • 3 parts
    1. hilum - blood vessels, lymphatics and nerves leave here
    2. medulla - stromal cells with testosterone secreting cells (similar to Leydig)
    3. cortex - primordial germ cells and follicles from primary, secondary, atritic

GERM CELL PRODUCTION - to ovary @ w10 of devlopment - immediately start meiosis and reach prophase 1 of meiosis (primary oocutes @ birth)

reawakened with each menstrual cycle - up to 20 cells begin to differentiate but only 1 acheives maturation -remainder resorbed

​

37
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FOLLICULAR DEVELOPMENT

  • @ cortex, many germ cells many = dormant primordial follicles with germ cell in theca from stromal cells
  • theca - simple squamous (primordial), later to cuboidal or columnar
  • then differentiates into granulosa cells = theca interna that begin to secrete oestrogen and theca externa (flattened) and follicle becomes secondary
  • further growth and development -> mature Graafian follicle with fluid-filled antrum
  • follices perish as atritic
  • once oocyte released from Graafian follicle theca persists and releases oestrogen and progesterone as corpus luteum

this slide - primordial follicles

38
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FOLLICULAR DEVELOPMENT 2

  • TL - secondary follicle
  • TR - primary follicle
  • BL - mature graafian follicle
  • BR - primordial follicle
39
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CORPUS LUTEUM

  • when Graafian follicle ruptures - antrum collapses = central blood clot
  • remaining thecal cells persist as corpus luteum
  • with lutinising hormone cells continue to secrete oestrogen and progesterone for 10 days - support secretory endometrium
  • if fertilisation occurs, corpus luteum persists for 4 weeks till placenta
  • most thecal cells produce progesterone but some at centre synthesise oestrogen - thecal lutein cells
  • final involution forms pale fibrous mass - corpus albican

this slide - theca interna and blood vessels

40
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CORPUS LUTEUM 2

  • centre contains pale staining amorphous material and blood clot
  • surround is wide band of cells from theca interna invaded by blood vessels
  • theca externa also contains many blood vessels

theca externa - stellate shape, small, pale

theca interna - large, globular, intense pink

41
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PITUITARY GLAND

  • anterior / posterior

POSTERIOR - neuronal origin, down growth of brain, pituitary stalk to median eminence of mid-brain @ floor of V3

supra optic and para-ventricular nuclei

  1. oxytocin
  2. vasopressin

ANTERIOR (TROPHIC) - epithelial origin. roof of primitive gut. adheres @ anterior border of posterior pituitary and surrounds stalk (pars tuberalis)

  1. growth hormone
  2. thyroid stimulating hormone
  3. follicle stimulating hormone
42
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PITUITARY PORTAL SYSTEM @ ANTERIOR

  • release trophic @ anterior pituitary regulated by factors @ neurons of hypothalamus
  • project to medial eminence
  • here they release secretions which are taken up by capillaries of pituitary portal and carried to anterior lobe
  • then act on hormone secreting cells

“portal system” = one that starts and ends @ capillaries

43
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ANTERIOR PITUITARY

  • 3 cell types
    1. stain heavily with acid dyes - alpha cells / acidophils /eosinophilic (dark red) growth hormone
    2. stain heavily with basic dyes - beta cells / basophils (dark blue) thyrotrophs/gonadotrophs/cotricotrophs
    3. stain weakly chromophobes, undifferentiated and no hormone
  • cells with no stain may be immature of any type

anterior pituitary is darker staining than posterior

44
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ANTERIOR PITUITARY 2

  • peptide based hormones in GRANULES
  • acidophils/basophils = small dark hormone containing granules
  • chromophobes = few or none
45
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POSTERIOR PITUITARY

  • PALE STAIN H&E
  • axonal tracts and nerve endings of cell bodies @ hypothalamus (supraoptic or paraventricular nuclei) @ walls of V3
  • swollen nerve terminals (Herring bodies) contain dark neuro-secreting granules - brown
  • granules contain:
  • 1) OXYTOCIN; 2) VASOPRESSIN
  • hormones bound to carrier protein that is also secreted
  • much tissue (blue staining) is nerve axon/connective tissue

OXYTOCIN - contraction of uterus, dilation of birth canal, contraction of myoepithelial cells around milk ducts + erect nipple for lactation

46
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PINEAL GLAND

  • small gland
  • backward projection of V3 between corpus callosum
  • covered by meninges
  • calcium may accumulate making it visible on brain X-Ray
  • irregular clumps of neurone-like pinealocytes linked by glial cells
  • innervation = autonomic
  • secretes melatonin - diurnal rhythms
  • UNIFORM

this slide - loose layers of meninges @ bottom, small blood vessels @ pia

47
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THYROID FOLLICLES

  • lies between neck of thyroid cartilage and 4th tracheal ring
  • midling thyroglossal ligamnet links gland to foramen caecum of tongue
  • THYROXINE AND CALCITONIN
  • thyroxine producing cells arranged in follicles (hollow spheres)
  • simple cuboidal epithelium
  • centre of each follicle filled with colloid rich thyroglobulin
  • height of cells varies with metabolic activity
  • flattened when dormant
  • emptying when active/ if full when dormant
  • thyroid gland contains lymphocytes
  • parathyroid gland is posterior
48
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FOLLICULAR PHASES

  • cyclical
  • synthesise thyroglobulin and store within follicle
  • after dormant period re-sorb and break down colloid and release active hormone (T4) into bloodstream
49
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C CELLS

  • calcitonin producing cells
  • clumps between follicles
  • parafollicular
  • sometimes between BM and follicular cells

calcitonin is antagonistic to parathormone

calcitonin @ high blood calcium levels

lowers serum calcium by promoting uptake of calcium in blood to bones (and muscles)

inhibits absorption of calcium from blood

50
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PARATHYROID

  • 4 @ dorsal surface of thyroid
  • mixture of fat cells and other secretory cells in clusters or short cords
  • CHIEF CELL - small an palely stained - very small granules = parathormone (calcium from bone to serum)
  • larger pink staining OXYPHIL cells fewer in number
51
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PANCREATIC ISLETS

  • 5% of pancreatic mass, 4 types:
    1. BETA - INSULIN - 70%
    2. ALPHA - GLUCAGON - 20%
    3. DELTA - SOMATOTSTATIN - 8%
    4. PANCREATIC POLYPEPTIDE SECRETING CELLS - 2%

beta cells at periphery of islets form cords to centre. other cell types lie between cords, plexus of capillaries/veins transport hormones to hepatic portal system

52
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ADRENAL GLANDS

  • OUTER CORTEX = STEROID HORMONES
  • INNER MEDULLA = ADRENALINE AND NORADRENALINE
  • centripetal blood supply
  • arterioles from capsular arteries to cortical sinusoids and direct links to medulla
  • both systems drain to central vein -> to renal vein or direct to IVC
53
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ADRENAL CORTEX

  • 3 zones
    1. OUTER GLOMERULAR (narrow) - ALDOSTERONE AND MINERALOCORTICOIDS
    2. INTERMEDIATE THICK FASCICULAR long parallel cords responsible for CORTISOL and GLUCOCORTICOIDS
    3. INNER RETICULAR ZONE anastomosing cords of cells that produce testosterone and other androgenics (DARKER STAINING)

do not store the steroid hormones they synthesise - discharged to sinusoids

accumulate droplets of fat and cholesterol from which hormones are synthesised = pale-staining of many cells

54
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ADRENAL MEDULLA

  • irregular clumps interspersed with blood vessels
  • 2 types of secretory cells
  1. ADRENALINE
  2. NORADRENALINE

stored in small neurosecretory granules in cytoplasm of cell until required

bathed in blood draining from adrenal cortex, thus influenced by steroid hormones

sympathetic stimulation

55
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TESTICLE

  • ovaries/testes/placenta are also hormone secreting

this slide - Leydig cells clumped between semniferous tubules

56
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EPIDERMIS

  • 4 layers
  1. GERMINATIVE - single layer
  2. SPINOUS - thickest
  3. GRANULAR - narrow with keratohyaline
  4. DEAD LAYER - dead keratinised squames, thickness varies depending on location and abrasion

DERMIS:

  • 2 layers
  1. rich in collagen (close to epidermis)
  2. deeper fatty layers
57
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KERATINISED EPITHELIUM

  • thickest @ soles of feet and on hands (hairless) - subject to compression
  • thin on parts of abdomen/thorax and lips
  • epidermis compact and boundary with dermis wavy creating dermal piapillae
  • at upper boundary = thin, darkly-staining granular layer, synthesises keratin that surrounds dead squames - prominent keratohyaline
58
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GERMINAL EPITHELIUM AND MELANOCYTES

  • majority = keratinocytes (from stem cells at germinal layer)
  • also within germinal layer = melanocytes, from neural crest of embryo
  • produce melanin - transferred to keratinocytes of basal and prickle cell layers
  • amount of melanin proportional to skin colour
59
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SPINOUS (PRICKLE) CELL LAYER

  • thickest layer - joined by desmosomes - prevent skin splitting when stretched
  • if shrink - desmosomes become obvious and cells appear spiny
  • within = LANGERHAN’S CELLS = pale cytoplasm and irregularly shaped nucleus
  • @ basal layer of epidermis = MERKEL CELLS - difficult to resolve, synapse with nerve fibres @ dermis and transmit fine touch
60
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HAIRY SKIN

  • roots of hair project from dermis, but are of epidermal origin
  • arise from geminative epithelium within hair bulb that contains melanocytes - hair colour
  • hair lengthens when a root sheath of epidermis with same layers as rest of skin but thicker BM = glassy membrane
  • surrounded by collagenous follicle sheath with erector pili (smooth muscle) (& autonomic nerve)
  • sympathetic stimulation = stand on end
  • to shaft = sebaceous glands (lubrication)
  • some parts of body with hairless sebaceous glands - face and groin
61
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FINGERNAILS

  • compacted keratin
  • arise from nail matrix cell under a fold of skin (eopnychium/cuticle) at proximal end of nail
  • nail lengthens across epidermal nail bed, remains firmly attached at distal end where underlain by a skin fold - hyponychium
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SWEAT GLANDS

  • dermis = 2 layers - outer with collagen and elastic fibres (fibrous layer) deeper = adipose (fatty tissue)
  • @ dermis = roots of hairs, glands, plexi of blood vessels, sensory transducers and nerve endings
  • most common = ECCRINE SWEAT GLANDS - lined by glycogen rich cells
  • tighly coiled knot of fluid secreting cells and straight duct with simple cuboidal epithelium
  • duct to surface of skin
  • coiled section surrounded by MYOEPITHELIAL CELLS
  • @ armpits and anus = apocrine sweat glands - earwax
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SENSORY NERVE ENDINGS (OSMIUM TETROXIDE)

  • many are too fine to be resolved except:
    1. PACINIAN CORPUSCLE - pressure @ dermis/pancreas - large structure with nerve ending at core - resembles an onion
    2. MEISSNER’S CORPUSCLE - numerous with spiral appearance @ dermal papillae
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EYELID

  • outside = thin hairy skin with row of prominent lashes
  • sweat glands discharge to outer surface of eyelid
  • inside = conjunctiva = stratified columnar with 2 cell layers
  • @ substance = single row of hairs, striated muscle (orbicularis oris) and glands to keep inside surface moist
  • largest gland = MEIBOMIAN GLAND modified sweat = lipid rich secretion - reduces evaporation
  • smaller sweat and sebaceous
  • this slide - meibomian gland
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BREAST

  • start as mainly adipose tissue, into which grow solid cords from the nipple
  • branch out/hollow to form lactiferous ducts but no milk producing alveolar cells
  • 15-20 segments formed by fibrous strands from nipple
  • suspensory ligaments of Cooper
  • ducts open to nipple via lactiferous sinuses
  • blind ended before pregnancy
  • adult inactive breasts are responsive to fluctuating hormones
  • @ 2nd half of each mesntrual cycle PROGESTERON PROMOTED OEDEMA - distension of segments
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NIPPLE

  • area of skin with raised fibro-muscular core
  • 12-20 small openings of lactiferous ducts
  • surrounded by areola with raised sebaceous glands = MONTGOMERY’S TUBERCLES
  • undergo pigmentation at pregnancy

lacteriferous duct = stratified cuboidal epithelium - if nucleus roughly circular = cuboidal

contains muscle which many change protuberance of nipple

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LACTATING BREAST

  • @ first trimester, enter proliferative phase stimulated by OESTROGEN, GROWTH HORMONE + CORTISOL
  • ducts divide and secretory alveoli develop at ends - columnar surrounded by flattened myoepithelial cells
  • alveolar cells mature and secretory material builds up within them and lumena, at the same time the stroma becomes depleted of adipose tissue
  • @ latter stages = lymphocytes

lactation suppressed by high levels of oestrogen and progesterone

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BREAST TISSUE - LACTATING

  • alveoli displace much of fat
  • contain secretory cells that produce milk proteins and fats and ion rich watery solution
  • milk protein and fat synthesis by same cells within alveoli but discharged differently
  • milk fats - apocrine secretion
  • milk protein - merocrine process

this slide = fibrous connective tissue - stroma

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LACTIFEROUS DUCT

gynecomastia = proliferation of lactiferous ducts

lobar carcinomas = dysplasia in small ducts

Phase 1 Histology COPY COPY (6 decks)

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