reproductive system Flashcards
intro
what is found in testis
how does sperm travel
male reproductive system composed of testis (tubica albugenia+ lobules+ seminiferous tubules+ interstitial cells), genital ducts, acc glands and penis
Testes produce sperm, contain endocrine cells (hormone prod: testosterone+ dihydrotestosterone). Genital ducts and acc glands produce secretions for nutrience of spermatozoa which both make up semen
Testis
surrounded by dense CT capsule= TUNICA ALBUGENIA. Thickens on post side forming MEDIASTINUM TESTIS where divides into 250 pyramidal compartments =TESTICULAR LOBULES (has Leydig cells-> testosterone+ 1-4 highly convoluted seminiferous tubules for sperm production)
develop: retroperitoneum of abd cav and moved during development, suspended in two halves of scrotal sac at ends of spermatic cord. carrying w it TUNICA VAGINALIS (serous sac). It’s kept at 34 degrees due to each testicular a surrounded rich pampiniform venous plexus containing cooler blood from testis. evaporation from sweat+ also contract/relax of cremastor m to pull testis closer to body
INTERSTITIAL TISSUE (androgen production): between seminiferous tubules w sparse CT=INTERSTITIUM, w fibroblasts, lymphatics and blood vessels (fenestrated cap).
- LEYDIG cell: large polygonal w central nuclei+ EOSINOPHILIC cyto. secrete testosterone F: promote dev of secondary sex organs, synthesized by enzymes of SMOOTH ER+ MITO. Stimulated by LH also called interstitial cell stimulating hormone ICSH. Synthesis begins: placenta release testosterone for duct+ glands development 3-4 months. then cells regress+quiescent to resemble fibroblast. Until puberty, where HYPOTHALAMUS activates and release GONADOTROPHIN-releasing hormone.
SEMINIFEROUS TUBULES
- germinal epi w basement membrane covered by fibrous CT innermost layer has MYOID CELLS (smooth m cell-weak contraction of tubules). 2 cells in epi: large non-dividing SERTOLI cells+ dividing cells of SPERMATOGENIC LINEAGE (4-8 concentric sperm layers produce cells that become sperm).
Sertoli cells tall pyramidal/COLUMNAR, oval EUCHROMATIC nucleus w prominent nucleolus
- 250-1000 tubules w 150-250um= d and 30-70um in length. Combined length of tubules in one test is 250m.
- tubule is convoluted loop linked by straight tubule, a narrow seg to RETE TESTIS (labyrinth of epi lined channels in mediastinum testis (has septa) move sperm to epididymis). starts w only sertoli cells then lined w SIMPLE CUBOIDAL EPI near rete testis (also lined by it; has few microvilli). 10-20 EFFERENT DUCTULES (Alternate w CUBOIDAL w microvilli into COLUMNAR CILIATED connect rete testis to HEAD EPIDYDIMUS.
Spermatogenesis
1) SPERMATOGENIA (projenitor stem cell where puberty begins): small round, darkly stained cells 12um= d; next to basement membrane + closely assoc w sertoli cells. It divides to progenitor A (pale staining ovoid nucleus that divide into itself or into type B (spherical+pale nuclei)
type B divides to form two cells
2) = PRIMARY SPERMATOCYTES (spherical +LARGEST of lineage w EUCHROMATIC nuclei, duplicate DNA so have duplicate chromatid ) which undergo meiosis I SECONDARY (22+X or Y, smaller, short-lived in interphase+ undergo quick meiosis II)
3) SPERMATIDS (22+XX or XY) DNA is half bc no S phase between meiosis (23?). Normal number restored by fertilization
SERTOLI CELLS (basement mem of seminiferous tubules)
adhere to basal lamina and send extensions into lumen; very closely associated w spermatogenic cells for metabolic and physical support
each cell support 30-50 germ cells in epi
abundant in SER, some RER, GA, high mito + lysosomes
Function: 1) basolat mem has TIGHT OCCLUDING JUNCTIONS which form blood-testis barrier within seminiferous epi to protection spermatogenic cells from attack. tightest in mammals. Newly formed spermatogenic cells migrate to adluminal compartment but remains adhered to sertoli and don’t compromise barrier.
2) support and nutrition (for spermatogenic cells- to produce/ transport to lumen for metabolite/ nutrition factors = trasnferrin (supply pasma factors to grow and differentiate).
3) exocrine: release water (through efferent ductule) that carry new sperm out of testis; produce nutrience+ ABP (androgen-binding protein) conc testosterone for spermiogenesis. promoted by FSH
endocrine: secrete INHIBIN (tell ant pituitary to inhibit FSH). during embryonic development, secrete MIS (Mullerian-inhibiting substance) cause regression of mullerian or paramesophrenic duct; if no MIS it develops into female reproductive system.
4) phagocytosis: during spermiogenesis, extra cyto shed as residual bodies and lysosome from sertoli is phagocytosed. no proteins from sperm pass barrier
INTRATESTICULAR DUCT (straight tubule, rete testis and efferent ductile for purpose of carry sperm from seminiferous t-> straight t-> rete testis-> efferent ductile-> head epididymis). rete drain into 20 efferent ductules lined w unusual epi (groups w CUBOIDAL epi w MICROVILLI alternate w COLUMNAR CILIATED cells; has saw tooth lumen). non ciliated collect fluid and ciliated create flow -> head of epid. smooth m layer help by weak contractions.
how sperm transported?
penis?
excretory genital ducts comprised of epididymis, ductus deferens, urethra. f: transport sperm from epididymis to penis during ejaculation
Epididymis (has one duct)
head (efferent ductile enter) body and tail (open to ductus deferens), long coiled duct of epididymis 4-5m; located posterior testis and store sperm; lined w PSEUDOSTRAT COLUMNAR epi w columnar PRINCIPAL CELLS w long STEREOCILIA (absorb water+uptake of residual bodies for spermiogenesis) and small round STEM CELLS. epi surrounded by smooth m cells (inner+outer longitudinal layer and circular in tail). contractions to move sperm during ejaculation.
sperm motile+ final maturation. Fluid in epididymis has GLYCOLIPID CAPACITATION FACTOR bind to CM + blocks acrosomal reactions +fertilizing ability until factor removed during capacitation process
enclosed by CT capsule (vasc) + tunica vaginalis
VANS DEFERENS (T Mucosa, TMuscularis TAdventitia)
long straight tube w thick muscular wall (longitudinal inner+outer and middle circular)-strong contraction, small lumen. Mucosa slightly folded, LP has ELASTIC FIBERS, empty into urethra. also PSEUDO but sparse sterocilia.
forms part of spermatic cord, (includes testicular a, pampiniform plexus and n). ductus def passes urinary bladder where enlarges=AMPULLA where epi thicker and more folded. within prostate gland both ampulla merge w duct of two seminal vesicles =EJACULATORY DUCT open to prostatic urethra.
ACESSORY DUCT+sex glands
seminal vesicles, prostatic gland and bulbourethral gland. F: secretion w sperm for semen.
seminal vesicles: 2, highly coiled muscular tubes, folds of mucosa 15cm. enclosed by CT capsule. lined w SIMPLE/PSEUDO COLUMNAR w secretory granules. LP elastic f + smooth m(inner circular and outer long only) and tunica adventitia. exocrine glands produce yellow (reg by testost). 70% of ejaculate has fructose (energy metabolite +aa inositol, citrate, ascorbic acid), prostaglandin (stimulate activity in female and fibrinogen (coagulate); 7.6pH
PROSTATE DUCT
sense organ and surrounds urethra below bladder. 2 x 3 x 4 cm; weighs 20g. collection of 30-50 tubuloacinar glands embedded in DENSE FIBROMUSC STROMA (w fibroelastric capsule extends to septa dividing it to lobules ) where smooth m contract at ejaculation. all empty to prostatic urethra, through center of prostate.
glands arranged in 3 zones: 1) TRANSITIONAL ZONE: 5% in v, superior portion of urethra and contains periurethral mucosal glands. 2) CENTRAL Z: 25% periurethral submucosal glands w longer ducts. 3) PERIPHERAL Z: 70% w prostate main glands and longer ducts. most common zone for inflamm and cancer.
glands lined w PSEUDOSTRAT COLUMNAR produce watery opalescent w glycoprotein, enzymes and prostaglandins, acid phosphatase, amylase and citric acid. prostate also secrete PSA prostate-specific antigens (SERINE PROTEASE that helps to liquefy the coagulated semen for slow release of sperm after ejac). PSA can leak to vasc but abnormal levels indicate abnormal glandular mucosa due to carcinoma or inflamm.
CORPORA AMYLACEA (0.2- to 2mm) prostatic concretion spherical w CONCENTRIC LAMELLAR BODIES; partially calcified secretions around desquamated cells. Contain GLYCOPROTEINS AND GAGS (keratan sulfate). increase w age but no sig.
BULBOURETHRAL GLANDS (cowpers): paired, round, 3-5mm =d in urogenital diaphragm nad empty to prox penile urethra. has several lobes w tubuloacinar secretary units(mucous), surrounded smooth m cells lined w SIMPLE COLUMNAR epi (mucous secrete). during erection the bulbour glands+ urethral glands (around penile urethra) secrete mucous to coat urethra for passage of sperm.
TESTOSTERONE DEPENDENT: bulbourethral gland, seminal vesicle and prostate (ACC glands)
PENIS
three cylindrical masses of erectile tissue+ penile urethra: two= corpora CAVERNOSUM(dorsal) + covered by tunica ALBUGENIA (Dense CT) and one is corpora SPONGIOSUM (surrounds urethra)+ at end expands to form GLANS.
3 tissues have VENOUS CAVERNOUS SPACES lines w ENDOTHELIUM separated by TRABECULAE w smooth m +CT continues w tunic. ??
penile urethra has PSEUDO COLUMNAR epi but glands STRAT SQ epi continues w epidermis. has URETHRAL GLANDS (mucous); prepuce (uncircumcised =foreskin w SABECOUS GLANDS on internal surface).
CENTRAL A in corpora cavernosa branches =HELICINE A (lead to cvernous vasc space in tissue). between central a + dorsal v has ARTERIOVENOSAL SHUNTS (no cap)
erection: triggered by sensory inn, controlled by autonomic n.
- parasym stimulation relaxes trabecular smooth m and DILATES helicine a. Increased blood flow to fill venous cav space which compress veins agaisnt tunica albuginea =block outflow to produce rigidity
- sympathetic stimulation helicine a and trabecular smooth m CONSTRICTS, decrease blood flow+P allow most blood to be drained.
which have adventitia
epi of each structure
I’m We Female reproductive system
development
follicle+development
ovulation
oogenesis
consists of two ovaries, uterine tube, uterus, vagina and external genitalia.
F: produce female gamete oocyte, provide environment for fertilization (uterine tube) and to hold embryo until birth.
OVARIES
almond shaped, 3 x 1.5 x 1 cm. covered by SIMPLE CUBOIDAL epi (germinal epi) / or mesothelium (simple cub/sq epi; continues w mesovarium, overlying a layer of dense CT capsule (tunica albugenia). Ovary has 2 parts w so sharp limit between them: CORTEX (highly cellular CT w many follicles+rich in FIBROBLASTS)+ MEDULLA (loose C, blood vessels (vasc) enter organ through hilum from mesentery suspending ovary.
develop
- month 1, PRIMORDIAL GERM CELLS migrate from yolk sac-> gonadal primordial, divide+ diff as OOGONIA. -month 2: 600,000 oogonia, 5th 7 million
- month 3: oogonia starts and arrests (after synpasis+ recomb) at prophase of M1= PRIMARY OOCYTES, surrounded by FOLLICULAR CELLS (flattened support cells). 7th most diff to primary oocyte, those who are lost (not w follicle) undergo ATRESIA- degenerative process. at puberty ovaries have 300,0000 oocytes. resume meiosis at ovulation during mestrual cycle. only 450 liberated through ovulation rest degenrates bc reproductive life ends 30-40 y.
Ovarian follicle
occyte surrounded by one/more layers of epi cells formed during fetal life PRIMORDIAL FOLLICLE= primary oocyte enveloped w single layer of flattened follicular cells in superficial area of cortex. Has 25um=d spherical, enlarge nucleus w chromosomes. (organelles conc near nuclei, mito, GA, RER). Basal lamina surrounds follicular cells and vasc stroma.
Follicular growth (FSH stimulates at puberty proliferate +stimulate follicle and fibroblast around follicle)
primordial follicle forms; oocyte grows rapidly reaching 120um; growth, mito increases, rer more extensive, GA, cortical granules ( specialised secretory granules) have protease in P.M
-UNLAMINAR PRIMARY FOLLICLE: undergo mitosis to form SIMPLE CUBOIDAL epi around growing oocyte. -MULTILAMINAR primary follicle: continued proliferation forms stratified follicular epi=GRANULOSA. Between oocyte + first layer of granulosa cells of primary follicle, ECM accumulates, forming ZONA PELLUCIDA. 5-10um thick REFRACTIVE EOSINOPHILIC LAYER, w 4 glycoproteins (ZP1-4) sperm receptors (secreted by oocyte) to induce acrosomal activation where FOLIPODIA of granulosa cells and MICROVILLI of oocyte penetrate ZP for communication via GAP J. -As primary follicles grow, goes deeper in cortex. The stromal cells around primary follicle diff-> FOLLICULAR THECA. -> theca interna+ external. theca internal POLYGONAL secretory cells is well vasc endocrine tissue, typical producing STEROID CELLS, secreting ANDROSTENEDIONE-> ESTRADIOL by enzyme (AROMATASE) (goes into follicle through basement membrane). Estrogen return thecae and stroma round follicle enter capillary and distributed in body. theca external CONSENSED CT, FIBROBLASTS+ smooth m cells+ small vessels -ANTRAL follicles (secondary follicle/ vesicular): small spaces between granulosa layer secrete follicular fluid (accumulate+ enlarges). Fluid has large hyaluronic acid, growth factors, plasminogen, fibrinogen and anticoagulant heparan sulfate proteoglycans w high conc of steroids and binding proteins. - ANTRAL F grow and granulosa cells-> cumulus oophorus protrude into lumen; connects ZP+ CORONA RADIATA+oocyte to granular layer. Accompanies oocyte when ovary leaves at ovulation. Antral of a mature follicle= GRAAFIAN FOLLICLE. accumulates more fluid+ develops to 2um=d. forming BULGE at ovarian surface. granulosa layer is thinner (cell don't multiply in proportion to growth). mature follicle has thick thecal layers develops at 90 days.
follicular ATRESIA: die by PHAGOCYTOSIS by macrophage+ fibroblasts (apoptosis of granular cells, autolysis oocyte, collapse of ZP). Atresia most prominent after birth+ puberty and pregnancy (bc of hormonal changes). antral follicle becomes more developed than others during menstrual cycle= dominant follicle undergoes ovulation while other antral +primary follicles undergo atresia. before atresion they release ESTROGEN to stimulate preparation of reproductary tract of fertilization occurs.
ovulation: day 14, of 28 cycle. graffian follicle forms bulge which against tunica albugenia forms STIGMA (whitish/ translucent ischimic area) blocking blood flow. Weakens ovarian wall a plasmin from capillary degrades collagen from tunica albugenia+ granulosa cells secrete prostaglandins+ hyaluran which loosens cells+ incr P + Vol+ viscosity of follicular fluid. prostaglandin triggers contraction of smooth m cells in theca external = RUPTURE and expels oocyte w corona radiate and follicular fluid-> uterine opening. degenerates in 24h if not fertilized. cells of ovulated follicle remaining in ovary redifferentitate w LH -> corpus luteum
corpus luteum CL F: temporary endocrine glands in ovarian cortex.
forms from folding of granulosa+ theca internal from ovulated follicular after rupture. due to LH cells can now secrete progesterone in addition to estrogen. FIBRIN CLOT forms in former antrum. granulosa cells = now GRANULOSA LUTEIN cells enlarge to 20-35um=d, and become 80% of CL (w out dividing). cells of theca internal = now THECA LUTIEN cells (half the size, darkly stain, aggregate in fold of CL. well vasc; LH cause secrete of progesterone androstenedione.
fate of CL depends on pregnancy or not. 1) LH cause progesterone 10-12 days and estrogen inhibits FSH. trophoblast of embryo produce human chorionic gonadotropin HcG to prevent drop in progesterone so uterus doesn’t shed. HcG maintain CL 4-5 months. placenta by then produces own progesterone and it degenerates = corpus albinas. Or CL stops producing steroid hormone= apoptosis, leading to menstruation+ increase FSH to developed the follicles. After apoptosis (from macrophage), FIBROBLASTS produce scar of dense CT = CORPUS ALBICANS
oogenesis: oogonium-> primary oocyte (diploid) in Prophase 1 of MI. where continues after puberty (LH+ estrogen)= secondary oocyte (haploid)+ first polar body (degenerating). arrested in Metaphase II until after fertilization.
uterus + tube
menstrual cycle
Uterus is pear-shaped organ w thick muscular walls. has left+ right uterine tubes and superior curved area between tubes=fundus-> narrows into isthmus and ends in cervix. cervical canal has constructed openings: internal+ external os which opens to vagina.
supported by set of ligs and mesenteries, has 3 layers
1) mucosa ENDOMETRIUM lined w SIMPLE COLUMNAR epi. thickness+ structure influenced by hormones. CILIATED + tubular UTERINE GLANDS. Tissue has COLLAGEN III+ abundant FIBROBLAST+ GROUND SUBSTANCE.
2 concentric zones: BASAL layer: adj, high cellular LP+ deep basal end of uterine glands. superficial FUNCTIONAL layer: spongy LP (less cellular), most of glands+ ground substance+ surface epi.(changes during mestrual cycle but basal doesn’t)
blood supply: ARCUATE A in myometrium send branches = STRAIGHT A (supply basal) + PROGESTERONE SENSITIVE SPIRAL A (supply functional layer)
2) thickest, highly vasc muscular layer MYOMETRIUM: has MYOCYTES, interwoven layers w/ inner circular and outer longitudinal muscle separated by STRATUM VASCULARE (thin band of CT).
during pregnancy HYPERPLASIA occurs(increase # smooth m cell), HYPERTROPHY of cell (size), increased collagen production to strengthen uterine wall= partition (strong contraction to expel infant). After preg smooth m cells shrink and apoptosis (of not needed collagen too).
3) outer CT: PERIMETRIUM continuous w ligs mostly serosa (some adventitia)
uterine tubes = OVIDUCTS
paired fibromuscular tubes 10-12cm, open into peritoneal cavity near ovary. composed of INFUNDIBULUM funnel shaped opening w finger like extension= FIMBRIN. AMPULLA longest+ fertilization occurs. ISTHMUS narrow seg near uterus. UTERINE =INTRAMURAL part opens into uterus.
wall: folded mucosa w SIMPLE COLUMNAR epi+ LP w blood vessels+ n +ciliated cells (to help propel ovum, triggered by estrogen they elongate undergo HYPERTROPHY during follicular growth phase + ATROPHY during luteal phase) + PEG cells (non-ciliated, dark stained, secretory- fluid for nutrients of ovum+fertiilize zygote ) + inner cir and outer longi muscle covered by thin SEROSA w visceral peritoneum + mesothelium. During ovulation hypertrophy+ increased blood flow enlarged and moves uterine tubes. infundibulum lies close to ovary to favour transport of secondary oocyte to tube-> ampula where fluid secreted by mucosa nutritive factors for oocyte+ sperm (capacitation) promoting fertilization. ECTOPIC PREG postinflamm scar tissue inables zygote to go to uterus so LP acts as endometrium and it implants, tube rupture causing haemorrhage. - LONGITUDINAL= prominent in ampula resembles labyrinth (become smaller the closer it is to uterus, NO FOLDS in intramural part).
Fertilization
sperm contact cells of corona radiate + acrosomal reaction: hyaluronidase for easier mov of sperm to ZP. Its proteins bind to ZP3-4 activating PROTEASE ACROSIN to degrade ZP. first sperm to pentrate through plasmollema induce Ca release, induces exocytosis of more protease. cortical reaction spread making ZP impenetrable PERIVITTALINE BARRIER. nucleus of secondary oocyte completes MII- sec polar body + ovum (female pronucleus), haploid nuclus of sperm head -> DECONDENSATION= male pronucleus. fusion of two pronuclei=zygote, a diploid cell.
Mestrual cycle
anterior pituitary reg ovarian hormone level to cause cyclic changes to endometrium until menopause 35-40.
- 1-3 days: bleeding from endometrium shedding and ruptured microvasc.
- 8-10 days: PROLIFERATIVE phase: follicular growth
uterine mucosa THIN after mestrual phase. theca internal develop-> estrogen increase plasma conc. acts on endometrium inducing cell proliferation to regenerate FUNCTIONAL layer lost during last phase. uterine lining SIMPLE COLUMNAR EPI+ glands STRAIGHT TUBULES w narrow lummen. SPIRAL A lengthen as functional layer re-established. endometrium 2-3 mm - 14 days: SECRETORY phase ovulation : (PAS)
begins due to progesterone secreted from CL, stimulate epi cells of glands (Accumulate glycogen and release via apocrine-w cyto+portion of P.M). accumulation dilates lumen= coiled glands. lacunae filled by microvasc+ uterus reach max thickness 5mm.
(if fertilization occurred embryo 5 days-> uterus) if no fertilization CL regress and progesterone+estrogen DECREASE 8-10 days after ovulation. 1) SPIRAL A in functional layer CONSTRICT by muscle contraction=cells become ischemic (die). 2) arterial cells secrete prostaglandins= strong local constriction+ hypoxia-> CYTOKINES (increase vasc permeability+ immigration of leukocytes).
leading to menstruation. leukocytes-> collagenase+ matrix metalloproteinase MMP for DEGRADATION of basement membrane.
basal layer not affected. in functional layer surface epi, most glands, stroma+ blood filled lacunae shed=mesntrual blood=menses.
cervix, vagina and external genitalia
cervix is the lower cylidrincal part of uterus. different histogic structure than rest of uterus
- Tunica mucosa: endocervical mucosa has simple columnar epi, thick LP (denser+ has NABOTHIAN CYSTS growth w mucous =benign) = ELASTIC FIBRE, branched tubular cervical glands+ . NO SPIRAL A, NO SHEDDING (thickness doesn’t change 2-3mm). + lymphocytes + plasma cells (local immune defense)
- transformational zone: region of cervix where open to vagina (external os) has STRAT SQ EPI. does change w menstruation.
- Tunica Muscularis: smooth m (less)+ dense CT
cervical mucous affected by mestruation cycle: ovulation: mucous abundant+watery to facilitate sperm mov. luteal/secretory phase: mucous more visible to HINDER passage. during pregnancy, highly viscous secretions to produce PLUG in cervical canal.
before partition=preg, macrophage remove collagen(CT REMOVELING), cervix softens so cervical canal can dilate.
Vagina
tunica mucosa- 150-250um, STRAT SQ EPI synthetise+ accumulate glycogen (stimulated by estrogen) NO GLANDS.
when desquamate bacteria convert glycogen-> lactic acid (low pH protection).
LP rich w ELASTIC FIBRES + narrow PAPILLAE projecting onto epi. hih $ lymphocytes+ neutrophils.
mucous covers mucosa (produced by cervical glands). during arousal, mucous secreted by great vestibular glands of vagina (within labia minora w vaginal+utethral orifices.)
Tunica muscularis- inner circular + thick outer longitudinal
Adventitia- dense CT rich in ELASTIC FIBRES. extensive venous plexus, lymphatics and nerves.
external genitalia=vulva
mucosa extensive sensory n+ tactile receptors
vestibule- wall w tubuloacinar vestibular glands
paired labia minora- folds of skin, NO HAIR follicles, SABECOUS GLANDS
paired labia majora- folds of skin, similar to skin of scrotum
clitoris- erectile homo struc to penis (corpora cavernosum)
mammary glands
develop: invagination of ectoderm along two ventrallines= MILK LINES from axilla-groin. highly modified APOCRINE SWEAT glands on each side of chest.
structure: 15-25 lobes of TUBULOALVEOLAR GLANDS separated by dense CT+ adipose tissue. each gland has own lactiferous duct (2-4.5cm long_ emerge independently from nipple. nipple has 15-25 pore opening 0.5mm =d.
Breast development during Puberty
-before puberty mammary glands are only lactiferous sinuss near nipple w small branching ducts. girls at puberty higher level of estrogen=breast to grow, ADIPOSE ACCUM, and DUCT system ELONGATES.
- non-preg, mammary glands have lobules = terminal duct lobular units TDLU. w small branching duct =rudimentary. LACTIFEROUS SINUSES STRAT CUBOIDAL EPI; lactiferous DUCT+ TERMINAL DUCT SIMPLE CUBOIDAL EPI w MYOEPI CELLS. larger ducts have smooth m encircling. duct system has LOOSE CT (vasc) but DENSER CT (less cellular) separating lobes. premesntrual phase -breast appear larger due to edematous (fluid filled in CT).
AREOLA - skin surrounding+cover nipple. SABECOUS GLANDS+ abundant sensory n continuous w mucosa of lactiferous sinus (strat cuboidal epi). abundant MELANIN, darker during preg. CR rich in smooth m fibers run parallel to lactiferous sinus = nipple ERECTION when contract
Breast during preg
-growth due to estrogen, progesterone, prolactin, placental lacteaogen. cause cell proliferation in secretary alvoeli (SIMPLE CUBOIDAL EPI) at ends INTRALOBULAR DUCTS. spherical alveoli w stellae myoepithelilal cells between secretory cells and basal lamina. stroma less prominent+ Ct within tissues infiltrated w lymphocytes, plasma cells (inc during late preg). akveoli+ duct become dilated by accumulation of COLOSTRUM (protein-rich fluid w leukocytes reg by PROLACTIN). IgA transferred here for passive acquired immunity to breast fed newborn.
Parturition, alveoli start lactation (also prolactin reg)+ enlarge large # protein synthesised and packed in secretory granules=MEROCRINE secretion to lumen (normal exocytosis- p.m folds…).
-LIPID DROPLETS short chain fa-> longer fa + cholesterol=APOCRINE secretion (accumulation on apical ends and excreted w portion of cyto+p.m). milk 4-5g fat.
- Lactose (GA) secreted w LACTALBUMIN. 7g of lactose in milk. responsible for osmotic gradient drawing watre+ ca into alveolar lumen.
milk: 1g protein/dL which includes aggregated CASEINS (44% of total proteins)+ ALPHA +BETA LACTOGLOBULIN (source of aa). less abundant lactoferrin to help w digestin+ immune F and mitogenic growth factors
child stimulate tactile receptors in nipple, stimulate oxytocin, contracts smooth m on lactiferous sinus+ducts+ myoepi cells of alveoli causing milk ejection (nervous stimuli-mad anxiety,etc inhibit oxytocin release so lactate)
postlacteal regression
weaning/stopped breast feeding, most alveoli degenrate (epi cells apoptosis, autophagy or sloughing (cast off) which is removed by macrophages. duct return to inactive state.
after menopause alveoli+ducts reduced, loss fibroblast, collagen and elastic fibres in stroma.
