Download Steroid-secreting cells

Endocrine System
Organization of endocrine system:
endocrine glands and endocrine cells
Structure characteristic of endocrine gland:
• hormone
• paracrine
• target organ
• target cell
• receptor
• Protein-secreting cells:
• Steroid-secreting cells:
Thyroid Gland
Capsule
lobules
ⅠFollicles
1. Follicular epithelial cells:
LM EM: colloid-containing vesicles
2. colloid: thyroglobulin, thyroxine: (tetraiodothyronine,
T4) triiodothyronine, T3)
Synthesis of thyroxines
triiodothyronine (T3) & tetraiodothyronine (T4):
1. Synthesize thyroglobulin in RER
(RER,G) → secreting granules → thyroglobulin (colloid)
2. Uptake of iodide and iodation of thyroglobulin
Iodide → iodide pump→ iodide oxidation in cytoplasm
→ colloid → bound to tyrosine residues of thyroglobulin →
iodated thyroglobulin.
3. I-thyroglobulin resorption and decomposition
iodated thyroglobulin → phagocytosis → phagosomes →
LYS →hydrolyze → T3 & T4.
4. Releasing of T3 & T4
Function of T3, T4:
1. elevates the basal metabolic rate.
2. body growth and nervous system development
3. Cretins: Retardation mental and physical development.
* Dwarf: growth hormone
function of follicular epithelial cells
Ⅱ parafollicular cells (C cells) :
LM:
EM:
Function: calcitonin
Adrenal Gland
• Adrenal cortex
• Adrenal medulla:
1. Adrenal cortex
(1) zona glomerulosa: LM:
function: mineralocorticoid (aldosterone)
(2) zona fasiculata: LM: EM: function: glucocorticoid
(3) zona reticularis: LM: androgen, less numerous
glucocorticoid and estrogen
1. Zona glomerulosa: Cells are
arranged in clusters beneath the
capsule. The secretion, the
mineralocorticoids (e.g.
aldosterone), participates in
electrolyte balance regulation.
2. Zona fasciculata: takes
about 65% of cortex. The
typical steroid-secreting cells
in the body are arranged in
straight cords, and run
perpendicularly to the capsule.
3. Zona reticularis: Adjacent
to medulla with obscure
outline. Cells are arranged in
net-like structure and
contain more lipofuscin
pigment granules.
2. adrenal medulla:
chromaffin cells, ganglion nerve cells, centre vein
function: adrenaline, noradrenaline
Pituitary Gland (Hypophysis)
• adenohypophysis
• neurohypophysis
hypophysis
adenohypophysis
neurohypophysis
Pars nervosa
infundibulum
Pars distalis Pars tuberalis Pars intermedia
Median eminence
Infundibular process
hypophysis
1. Adenohypophysis
1.1 pars distalis (anterior lobe)
(1) chromophil cells
① acidophilic cells: LM:
A. somototroph (growth hormone, GH)
B. mammotroph (mammotropin)
② basophilic cells: LM:
A. thyrotroph: thyroid stimulating hormone (TSH)
B. gonadotroph:
follicle stimulating hormone, FSH (female, male)
luteinizing hormone, LH (female, male)
interstitial cell stimulating hormone, (ICSH)
C. corticotroph (adrenocorticotrophic hormone, ACTH)
lipotrophic hormone ,LPH
(2) chromophobe cells:
LM:
EM:
2. pars intermedia:
follicles, chromophobe cells and basophilic cells
melanocyte stimulating hormone, MSH
3. pars tuberalis
abundant longitudinal
capillaries
chromophobe cells and
small amounts of acidobasophilic cells, the later
secretes FSH and LH
4. Blood Supply of Adenohypophysis
superior hypophyseal artery
fist capillary loops
hypophyseal portal
venule
second capillary loops
Hypophyseal portal
system
inferior hypophyseal
vein
2. Neurohypophysis
the organization: unmyelinated never fibers and
neuroglial cells
•
•
•
•
Herring body (LM, EM)
pituicyte
antidiuretic hormone (ADH) , vassopressin,
oxytocin (OT)
Pineal Body
The organization: pinealocytes, neuroglial cells and
unmyelinated never fibers
• Pinealocyte :
• LM: brain sand
• Function: melatonin
Diffuse Neuroendocrine System
• Amine Precursor Uptake and
Decarboxylation Cells
so called APUD cells
diffuse neuroendocrine system:
adrenal cortex
ultrastructure of steroid-secreting cells
pars distalis of adenohypophysis
neurohypophysis
内皮
轴突内
的分泌
颗粒
Herring bodies in EM
松果体
细胞
神经胶
质细胞
脑砂
毛细
血管
毛细
血管
pineal body
pinealocytes and brain sand