Repro Flashcards
what does spermatic ducts include?
epididymis
ductus deferens
ejaculatory duct
accessory sex glands include?
seminal vesicles
prostate
bulbourethral glands
functions of repro system?
spermatogenesis
production of seminal fluid
steroidogenesis
sex
testes are the site of —- and —-.
spermatogenesis and steroidogenesis
what is the benefit of extra abdominal location of testes?
maintains temp 2-3 degrees below body temp==> vital for spermatogenesis, but not necessary for steroidogenesis.
what controls the position of testes in relation to temperature?
the contraction of cremaster muscle
what is the layer of testes that descends down from abdominal cavity?
tunica vaginalis
tunica vaginalis is a remnant of — which is lined by — and produces — to —- &—.
peritoneum
serous membrane
serous fluid to reduce friction and facilitate movement
tunica albuginea is a —- which — and forms septa.
dense and thick CT capsule
protects
what forms the CT septa of testes?
t. albuginea
what does tunica vasculosa contain?
blood vessels
what are the prominent structures visible in a low mag of testes?
lobules which contain seminiferous tubules
what is the site of spermatogenesis?
seminiferous tubules
what is the tissue in between the seminiferous tubules and what does it contain?
CT stroma which contains leydig cells
site of steroidogenesis?
CT stroma by leydig cells
prominent features of leydig cells?
abundant lipid droplets
lots of sER, large, polygonal eosinophilic
testosterone is synthesised from — which is collected via — in leydig cells.
cholesterol
lipid droplets
when do leydig cells become active?
early in foetal development to secrete testosterone for gonadal development and descent of testes.
are leydig cells always active in their secretions?
no. they stop in 5 months of foetal life till puberty.
what are the effects of testos after puberty?
- enlargement of penis, testes and prostate.
- initiation of spermatogenesis
- initiation of accessory sex gland secretions
- development of secondary sex characteristics
what are the effects of testos production throughout life?
essential for maintenance of structures developed in puberty, maintenance of bone and muscle strength and erectile function
seminiferous tubules are lined with spermatogenic epithelium which is a —- epithelium which contain — and —-.
complex stratified epithelium
sertoli cells and spermatogenic cells
sertoli cells are —- epithelial cells which support the development of —-.
true epi cells
spermatogenic cells
what tissue surrounds the semi tubules and what is its function?
myoid cells
contractile cells which through peristaltic contractions move the sperm and testicular fluid through tubules to excurrent ducts.
what does spermatogenic epithelium include?
sertoli cells
spermatogenic cells/germ cells
what are the stages of spermatogenic cell development?
stem cells which are located basally=spermatogonia ==>undergo spermatogenesis to turn into mature sperm==> migrate towards lumen as they mature.
what does spermatogenesis consist of?
mitosis (spermatogonium undergo mitosis to form primary spermatocytes), meiosis (from primary to secondary and spermatids) and spermiogenesis (final morphological differentiation from round cell to mature sperm).
where are spermatogonia located?
basal lamina of semi tubules
types A spermatogonia ?
Type A: • Dark = stem cell reserve • Mitosis to replace themselves & maintain stem cell reserve • Light = renewing stem cells • committed to differentiate, but first undergo multiple mitotic divisions to increase number
type B spermatogonia?
Type B = last step in
spermatogonial phase
• Condensed chromatin
what is the step after formation of type B spermatogonia?
Type B spermatogonia undergo mitosis to produce primary spermatocytes.Immediately replicate their DNA and enter prophase I of meiosis. (22 days) • “Crossing Over” occurs, creating new combinations of DNA within chromosomes.Undergo first meiotic division to become secondary spermatocytes • Do not replicate DNA, immediately enter prophase II of meiosis • Complete 2nd meiotic division rapidly (within a few hours) to form spermatids
what happens at spermatid stage?
No changes to DNA. No cell division
Morphological transformation
(differentiation) into mature sperm
= spermiogenesis.
what occurs in spermiogenesis?
• Extensive cellular remodelling • Spermatids physically attached to Sertoli cells during this transformation • Start as small, round cells, round nuclei • Nucleus condenses • Formation of acrosome • Development of flagellum • Reduction of cytoplasm • Removal of excess organelles (Ribosomes, ER, Golgi etc) -development of spermartozoa
Final maturation of spermatozoa occurs in?
epididymis
what does the head of spermatozoa contain and function if each part?
• Acrosome • Contains enzymes to penetrate zona pellucida of oocyte → fertilisation • Nucleus • Haploid, extremely condensed, inactive
what does the tail of spermatozoa contain and function if each part?
- Neck → Centriole
- Midpiece → Mitochondria
- Principal piece & End piece → Flagellum
- contains axoneme
what determines the sex of the baby?
sperm
what cells protect spermatogenic cells and how?
sertoli cells- their processes surround spermatogenic cells for duration of
spermatogenesis.
• Provide nutrients & growth factors, remove
waste
• Phagocytose components of spermatids in
final stage of spermiogenesis
how are sertoli cells stimulated?
Stimulated by FSH and testosterone
what are secretory functions of sertoli cells?
• Exocrine: secrete fluid into seminiferous tubules, facilitates movement of sperm along tubules to ducts • Endocrine: secrete several hormones including inhibin (-ve feedback FSH)
immunological function of sertoli cells?
form the blood testes barrier
what constitutes the blood testes barrier?
unique sertoli to sertoli junctional complexes attached basolaterally to cells which are exceptionally tight and junctions =zonula occludens
function of blood testes barrier?
Segregates luminal fluid, allowing strict control over its composition Prevents passage of toxic agents from blood into tubules. Segregates pre-meiotic and post-meiotic
why is it important to isolate spermatocytes from blood?
Post-meiotic = different DNA = antigenic
• They Isolate post-meiotic from immune system
Early primary spermatocytes pass through
junctional complex before they cross over.
• Antigens produced by sperm can’t enter
circulation
• Circulating antibodies can’t reach sperm.
If BTB fails, anti-sperm antibodies are
produced ➔ can cause infertility
how long does spermatogenesis take?
74 days + 12 days to pass through epididymis and mature.
semen is manufactured in —-, – and — in epididymis, ejaculation forces sperm into — which meets the seminal vesicles to form—.
It passes through – and empties into — which carries through —.
testes storage and maturation vas deferens ejaculatory duct prostate urethra penis
the bulk of the seminal plasma is from?
seminal vesicles then prostate
what are the phases of ejaculation? explain each.
Emission • Contractions in vas deferens (sperm), seminal vesicles and prostate expel fluid • Combined and stored in prostatic urethra (semen) • Contractions in bulbourethral gland Expulsion • Often associated with orgasm • Contractions in smooth muscle of urethra and rhythmic contractions in striated muscles of perineum propel semen from prostatic urethra • Ejection of combined semen through penile urethra
how do sperm become mature?
Immature sperm enter at head (incapable of fertilisation) • Sperm take ~12 days to travel through and undergo further maturation • Gain motility • Further condensation of nucleus • Further reduction of cytoplasm • Decapacitation: Modification of acrosome to inhibit fertilising ability. This is reversed during capacitation in female reproductive tract
tubules in epididymis are lined with?
pseudostratified epithelium
what are the cells inside epididymis epi?
- Basal cells
* Principal cells => covered with stereocilia
function of principal cells of epididymis?
• Absorption of remaining fluid coming
from seminiferous tubules
• (100-fold concentration of sperm).
specific functions of epididymis epi?
• Phagocytosis of material released by
maturing sperm and any degenerates
• Secretion of factors that aid in sperm
maturation
function of smooth muscle surrounding epididymis epi?
• Head & body: peristalsis to move sperm
along
• Tail: intense contractions at ejaculation
function of vas deferens?>
Strong peristaltic contractions at
ejaculation (emission) carry sperm from
epididymis to seminal vesicles
vas deferens is a — tube.
muscular
epi of vas deferens?
• Pseudostratified epithelium-covered with stereocilia.
what are some features of vas deferens?
• Folded lumen => Probably due to contraction of muscle during tissue fixation • Very muscular wall: 3 layers of smooth muscle • Inner longitudinal • Middle circular • Outer longitudinal
what controls the secretions from seminal vesicle?
testosterone
what makes up seminal plasma from seminal vesicle?
• Fructose – large amount
• Amino acids, proteins, enzymes, Vitamin C,
Prostaglandins
functions of each component in seminal plasma from seminal vesicle?
• Fructose = main energy source for sperm
• Fluid is alkaline, neutralises acidic vaginal
pH to facilitate sperm survival
• Suppresses immune function in female
reproductive tract
epithelium of seminal vesicle?
Psueudostratified or simple columnar
epithelium
features of seminal vesicle epi?
• Highly secretory
• Contain many secretory granules,
abundant golgi & rER (TEM).• Lamina propria = CT, v. elastic
• Thick smooth muscle wall
• Contraction during ejaculation (emission
phase)
secretions from prostate is controlled by—.
testosterone
what are the components of secretions from prostate?
• Prostatic acid phosphatase, fibrinolysin,
citric acid & prostate-specific antigen
functions of secretions from prostate?
- Enzymes liquify semen after ejaculation
* Also alkaline, neutralise acidic vaginal pH
how is retrograde ejaculation prevented from prostate to bladder/
contraction of bladder neck at ejaculation.
what is the prominent histo feature of prostate?
Contains 30-50 compound
tubuloalveolar glands
prostate gland tubules are surrounded by —.
fibromuscular stroma
what is the function of fibromuscular stroma in prostate?
• Contractions at ejaculation
(emission) pump alveolar
secretions into urethra
prostatic urethra is lined with?
transitional epi
tubuloalveolar glands are lined with?
• Generally simple columnar epithelium but can
vary (simple cuboidal to pseudostratified)
alveoli contain material in their lumen. what is this called?
Alveoli can contain prostatic concretions (aka
corpora amylacea)
• = concentric lamellated material
• Thought to be precipitated prostatic secretions
Can become calcified
bulbourethral glands empty into —
penile urethra
what controls bulbo gland’s secretions
testosterone
what do bulbo glands produce and their functions?
mucin
• Mucus-like secretion released during erection
(= pre-ejaculate)
• Neutralise acidity of urethra (due to residual
urine)
• Lubricates penile urethra for passage of
sperm
main tissue in penis?
vascular erectile tissue
how does the epi of urethra change from bladder to terminal penis?
- Neck of bladder = transitional
- Prostatic urethra = transitional
- Membranous urethra = pseudostratified
- Most of penile urethra = pseudostratified
- Terminal portion of penile urethra = non-keratinised stratified squamous
what are the main components of penis?
3 vascular erectile tissues, 2 dorsal-corpora cavernosa
1 ventral-corpus spongiosum
the primary erectile tissue in penis is?
corpora cavernosa
which component of penis contains urethra?
corpus spongiosum
what surrounds the corpora of penis?
dense fibroelastic layer-tunica albuginea which also surrounds each.
what covers tunica albuginea?
covered by CT and thin skin.
90% of blood in penis is within —-.
cavernous sinuses in corpus cavernosum
what epi lines the cavernous sinuses?
endothelium
what surrounds the cavernous sinuses?
CT trabeculae between- which contains smooth muscle, Helicene arteries, and nerves
where are veins positioned inside the corpora?
edge of tunica-peripheraly located.
how does the tunica albuginea differ for each corpora-relate to function?
corpus cavernosum-thick, dense CT
corpus spongiosum-thinner and more elastic-to prevent compression of urethra during erection, allowing semen to be released at ejaculation.
similarities and differences between the corpora?
both contain similar cavernous sinuses and CT septa. But in spongiosum there’s 10% of blood.
Spongiosum contains penile urethra and small mucus glands which empty into urethra.
erection is under— stimulation.
parasymp
describe the steps in erection?
- Dilation of helicene arteries
- ↑ blood flow
- Relaxation of SMCs in trabeculae
- Cavernous sinuses fill with blood
- Corpora cavernosa expand
- Veins compressed against tunica albuginea, blocking venous outflow
- Erection achieved (hydraulic pressure)
— ends erection.
symp stimulation
describe steps after erection ends.
•Constriction of helicene arteries
•Contraction of SMCs in trabeculae
•↓ blood flow to cavernous sinuses
•↓ pressure on veins, unblocking venous outflow
•Blood drains
•Erection subsides & penis returns to flaccid state
In flaccid penis, SMCs under tonic contraction, limits blood flow into sinuses
pacinian corpuscles in penis are responsible for —,– and —.
sensitivity, touch and pressure.
what are the striated muscles at base of penis and their function.
bulbospongiosus
ischiocavernosus
Rhythmic contractions increase pressure in corpus spongiosum, propelling semen through urethra =expulsion phase of ejaculation
role of estrogen?
– Growth, maturation of sex organs – Female sex characteristics at puberty – Breast development, adipose accumulation
roles of progesterone?
– Prepare uterus for
pregnancy
– Prepare mammary gland
for lactation
Gametogenesis is production of — .
eggs
what is the epi of ovary?
germinal epi:simple cuboidal cells
what are the layers of ovary?
Germinal epithelium Tunica albuginea Cortex – follicles Medulla – large blood vessels
germinal epi is continuous with —.
mesothelium that covers mesovarium
how do germ cells develop in foetus?
Migrate from embryonic yolk sac into
embryonic gonad
when do the oocytes stop mitosis?
at birth-they are arrested at prophase 1.No new oocytes are produced after birth
what are the three types of ovarian follicles?
- primordial follicles;
- growing follicles, which are further subcategorized as primary and secondary (or antral) follicles; and
- mature follicle or Graafian -follicles.
when do primordial follicles appear during development?
3rd month
where are primordial follicles located, their feature?
found in the stroma of the cortex just beneath the tunica albuginea. A single layer of squamous follicle cells surrounds the oocyte
how do primordial cells become primary follicle?
As a primordial follicle develops into a growing follicle, changes occur in the oocyte, in the follicle cells, and in the adjacent stroma. Initially, the oocyte enlarges, and the surrounding flattened follicle cells proliferate and become cuboidal/granulosa cells. At this stage—that is, when the follicle cells become cuboidal—the follicle is identified as a primary follicle.
-zona pellucida forms from the proteins secreted by the oocyte
-Stromal cells surrounding follicle become
theca interna, theca externa cells
-Move deeper into ovary due to proliferation of
granulosa cells
zona pallucida is composed of?
ZP glycoproteins secreted by the oocyte: ZP-1,ZP-2,-3,-4.
zona pellucida is — staining.
acidophilic
how does late primary follicle develop?
follicle cells give rise to stratified epi-granulosa cells.
extensive gap junctions develop between granulosa cells and oocyte.
characteristics of theca interna?
– Highly vascularised – Cuboidal secretory cells – Steroid-producing – LH receptors – synthesise and secrete androgens
feaTures of theca externa?
– Outer layer of CT
– Collagen, smooth muscle
fibres
how to we classify secondary follicles?
presence of antrum
how does secondary follicle develop?
When the stratum granulosum reaches a thickness of 6 to 12 cell layers, fluid-filled cavities appear among the granulosa cells (Fig. 23.6). As the hyaluronan-rich fluid called liquor folliculi continues to accumulate among the granulosa cells, the cavities begin to coalesce, eventually forming a single, crescent-shaped cavity called the antrum. The follicle is now identified as a secondary follicle or antral follicle.
the follicular antrum contains ?
the fluid is called liquor folliculi, rich in Hyaluronana
what is required for transition from primary follicle to secondary?
FSH
GF
Ca ions
Maximum diameter of oocyte ?
125 microns
what theca interna cells and granulosa cells secrete after secondary follicle development and their path?
Theca interna:
-has LH receptors, LH from pituitary binds to this and secretes androgens. The androgens go to granulosa cells.
Granulosa cells
– Have FSH receptors-FSH binds to these and stimulates the conversion of androgens from Theca interna into estrogens.
– have enzymes Convert testosterone (type of androgen)
into estrogens.
What occurs after secondary follicle maturation?
mature Graafian follicle develops.
features of Graafian follicles?
-Large – 10mm or more diameter-quite large
-Single fluid filled antrum taking up most of
volume of follicle
Specialisations of granulosa cells-formation of
– Cumulus oophorus
– Corona radiata
what’s involved in ovulation?
High level of estrogens (from follicles) lead
to surge in LH and FSH (positive feedback)
– Proteolytic enzymes
– Resumption of meiosis 24hrs before ovulation
– Secondary oocyte – arrested at metaphase II
until fertilisation
Oocyte + corona radiata + fluid ovulated
what remains after ovulation?
corpus luteum-granulosa cells and theca cells
what occurs after ovulation to the granulosa cells and theca cells of ovaries?
they undergo luteinisation-increase in size and lipid accumulation.
Steroid secreting – abundant sER, mitochondria with tubular cristae.
where does the yellow appearance of c.luteum come from?
Lipochrome – lipid soluble pigment, yellow
appearance
types of cells in corpus luteum and their secretions?
Granulosa lutein cells – Develop from granulosa cells of follicle – 30µm diameter – Secrete estrogens, progesterone and inhibin.
Theca lutein cells – Develop from theca interna – Smaller (15µm diameter), darker staining – Secrete androgens, progesterone
what signals to stop FSH from pituitary in females?
inhibin released from c.luteum
if no fertilisation occurs, — develops.
corpus albicans-gross white scar, intercellular hyaline material accumulation which get absorbed into ovary later
what happens to rest of the follicle cells that haven’t developed into primary or secondary follicles?
undergo atresia -can occur at any stage.
what does atresia involve?
Apoptosis of granulosa cells Degeneration and autolysis of oocyte Zona pellucida folded, collapses, phagocytosed by macrophage Basement membrane forms glassy membrane – wavy hyaline structure
what type of CT surrounds uterine tube?
External serosal layer – Mesothelium, thin layer connective tissue Muscular layer – Inner circular – Outer longitudinal
describe the mucosa of uterine tube.
Highly folded (in ampulla), highly vascularised Simple columnar epithelium – Ciliated cells – Nonciliated peg cells
which part of the uterine tube has more foldings?
ampulla
how does the uterine tube change during menstrual cycle?
Hypertrophy during follicular phase (during development of oocyte)
Atrophy during luteal phase (after ovulation)
Estrogen – ciliogenesis to move the egg down
Progesterone – increase in secretory cells-after ovulation, need nourishment
Peak height of epithelial cells 30µm at time
of ovulation
– Half height just before menstruation
What lining covers Uterus?
perimetrium -serosa
layers of myometrium?
3 layers (indistinct) – Inner longitudinal – Middle circular – Outer longitudinal
function of myometrium?
During pregnancy – Hypertrophy (50µm to 500µm in length) – Hyperplasia – Differentiation of undifferentiated cells
why there are changes in endometrium during menstrual cycle?
Cyclical changes during menstrual cycle – Prepare for implantation of embryo and subsequent fetal development
layers of endometrium?
– Functional layer Thickest part, closest to lumen -Can be called Stratum functionalis – Basal layer Retained during menstruation Regeneration of functional layer Stratum basalis
what is endometrial epithelium?
Luminal epithelium
– Simple columnar
– Secretory and ciliated
cells
prominent histo feature of endometrium?
Endometrial stroma – Highly cellular – Simple tubular glands invaginations of luminal epithelium
luminal epi cells of endometrium are continuous with —.
glandular epi cells
what is the unique feature of uterine luminal epi cells?
Only cells in body that transform from nonreceptive to receptive in short time frame (attachment or non-attachment of blastocyst).
how does the uterine luminal epi cells change ?
change with menstrual cycle-after ovulation you get flattening of the simple columnar cells, accumulation of vesicles inside, making them become receptive.
describe the vasculature of the uterus and their location.
the uterine artery comes in, becomes arcuate then radial within myometrium. Straight artery – basal layer of endometrium. Spiral artery – extends into functional layer (stratum functionalis) – Highly coiled – Important in menstruation Arterioles, capillaries, venules…
what influences the functional layer of endometrium to grow?
estrogen.
when does proliferative phase of uterus occur, what happens and what causes it?
synced with follicular phase of ovarian cycle, endometrium grown to 3mm in thickness via the control of estrogen. Day 5-14
prior to ovulation the phase is called—, after is called—.
proliferative phase
secretory phase
features of proliferative phase of endometrium?
Regeneration of endometrium – Mitotic figures in epithelium Spiral arteries – Lengthen, not in upper 1/3rd of endometrium Glands – Narrow, relatively straight – Some glycogen in basal glands
when does secretory phase of uterus occur and what controls it?
Luteal phase of ovarian cycle Days 15-26 Progesterone controls it Endometrium 5-6mm thick Oedematous stroma
features of endometrium structure in secretory phase
Glands – Enlarged – Corkscrew shape – Sacculated appearance Glycogen rich secretory products.
Spiral arteries
– Lengthen to nearly reach surface
– More coiled
Stromal cells
– Transform into decidual cells
– Large pale cells
– Rich in glycogen
what is secreted during secretory phase?
estrogen and progesterone
what causes the menstrual phase to initiate?
Decline in estrogens and
progesterone
through degeneration of corpus luteum
what occurs during menstrual phase?
Periodic contractions of spiral arteries caused by decline in estrogen and progesterone. – Ischaemia of functional layer, blood flow remains to basal layer – Necrosis of stromal cells – Disruption of surface epithelium and rupture of blood vessels
what does the menstrual discharge consist of?
– Blood, uterine fluid, stromal cells and
epithelial cells of functional layer
what is inhibited during menstrual phase?
blood clotting factors and fibrinolysis.
what is endometriosis?
-Presence of endometrial tissue outside uterine cavity -Retrograde menstruation
how does cervix compare with uterus?
More connective tissue, less smooth muscle than body of uterus Elastic fibres Large branched glands No spiral arteries
epi of different parts of cervix?
Epithelium – Endocervix – simple columnar (continuous with uterus) – Ectocervix – stratified squamous (continuous with vagina)
does the mucosa of the cervix change during menstrual cycle?
nope. – No change in thickness
during menstrual cycle
– Not sloughed off during
menstruation
what produces cervical mucus and their function?
Produced by glands
Lubrication of vagina
what controls cervical mucus and why?
Change during menstrual cycle, under
hormonal control
Most stages – prevents passage of sperm
into uterus
how does the mucus change during mestrual cycle?
Ovulation time
– Mucus production increased 10x
– Less viscous, ‘egg white’ consistency
– Favourable for sperm migration
are nabothian cysts pathological?
no their normal. become more as you age, they are basically blocked cervical glands.
all cases of cervical cancer is asso with—.
HPV
type of mucosa epi of vagina?
– Non-keratinised stratified
squamous epithelium
– Connective tissue papillae
what CT covers vagina?
Adventitia
– Inner dense CT
– Outer loose CT
what are the features of vaginal mucosa?
Stratified squamous epithelium – Glycogen Source of energy for lactobacillus – maintain vaginal pH. Unlike hyaline granules of keratin in skin.
Lamina propria – Highly cellular, loose ct – Deeper region has dense submucosa Some erectile tissue – thin walled blood vessels.
what inhibits development of male mammary glands?
testosterone at puberity
During development, multiple glands develop along paired— thickenings called — that extend from the developing — to the developing —.
epidermal
mammary ridges
axilla
inguinal region
what controles mammary gland growth in females?
estrogen
how does the mammary gland grow in females?
- estrogen stimulates further development of mesenchymal cells.
- The mammary gland increases in size, mainly due to the growth of interlobular adipose tissue.
- The ducts extend and branch into the expanding connective tissue stroma.
- Proliferation of epithelial cells is controlled by interactions between the epithelium and the specialized intralobular hormone-sensitive loose connective tissue stroma.
- By adulthood, complete ductal architecture
what is the mammary gland composed of and their epithelia?
- 15-20 irregular lobules (tubuloalveolar glands)
- Lactiferous duct-keratinised stratified squamous epi
- Lactiferous sinus-2 layers cuboidal epi
- Duct-simple columnar or cuboidal epi
- fibrous CT in between
- adipose tissue
what are the structures in an adult nipple?
- opening of lactiferous ducts
- sebaceous glands, sweat glands, montgomery glands (intermediate between sweat glands and mammary glands)
- nerves
what constitutes the TDLU?
– Successive branching of lactiferous ducts
– Terminal ductules (or secretory alveoli)
– Intralobular collecting duct
– Intralobular stroma
what are the cell types in TDLU?
– Glandular
-Line duct
– Myoepithelial
-Between epithelial cells
and basal lamina
-Contraction – milk
ejectionmain feature of inactive mammary gland histo?
lots of dense CT
how does the mammary gland changes during menstrual cycle?
Follicular phase
– Intralobular stroma less dense
– Terminal ductules – cuboidal cells, no lumen
Luteal phase
– Epithelial cells increase in height
– Lumina appear in ducts – some secretion
– Oedematous connective tissue
==>May explain breast tenderness and increase size during luteal phase
what are the hormones required to complete the development of mammary gland during pregnancy?
– Estrogen and progesterone from Corpus luteum and placenta – Prolactin from Pituitary gland – Gonadocorticoids from Adrenal cortex
how does the mammary gland grow during pregnancy?
First trimester
– Terminal ductules form;
Elongation, branching
Proliferation and differentiation of epithelial and myoepithelial cell
Second trimester – Alveoli form from terminal ductules – Immune cell infiltration – Growth of alveoli ==>Large Increase mass of breast.
Third trimester
– Maturation of alveoli-can produce milk
– Glandular epithelial cells become Cuboidal, basal nuclei, develop Secretory vesicles and lipid droplets
– Breast size increase due to
1. Hypertrophy of secretory cells
2. Accumulation of secretory products in lumen
difference between pregnant and inactive mammary gland?
inactive; lots of CT
active; lots of glandular tissue, less CT, large intralobular duct
what are the hormones required to produce the milk and when are they released?
prolactin and human placental lactogen- which were suppressed during pregnancy by estrogen and progesterone. They are released at birth due to sudden drop in estro and proges by delivering the placenta.
Also, oxytocin is also released which is involved in contraction of myometrium at birth and myoepi cell contraction for milk production.
stages of milk production at a cellular level?
Merocrine secretion – Protein component – Extensive rough ER – Secretory vesicles to Golgi – Packaged for exocytosis
Apocrine secretion;
– Fatty or lipid component of milk
– Lipid droplets accumulate at top of cell, being pinched off surface
what does a lactating mammary gland look like?
even less CT, majority is glandular and intralobular ducts, secretions in lumen, large epi cells.
what is produced from mammary glands immediately following birth?
Colostrum-Alkaline yellowish secretion
Higher protein, lower lipid, carbohydrate
content than breast milk, Secretory IgAs (and other antibodies)
– Passive immunity to newborn
– From immune cells in stroma of glandular component
– Important for establishing gut microbiome of
infant.
how is lactation initiated after birth?
-Suckling (and looking at, talking about,
hearing baby cry)
-Signals to hypothalamus – inhibits
prolactin-inhibitory factor (dopamine)
-Release of prolactin from ant pituitary
– Milk production
Release of oxytocin from posterior pituitary
– Myoepithelial cell contraction
– Contractions of uterine wall
