0x Histology of the Endocrine System Lecture Flashcards Preview

Endocrine (updated 2016) > 0x Histology of the Endocrine System Lecture > Flashcards

Flashcards in 0x Histology of the Endocrine System Lecture Deck (45):


a branch of biology and medicine dealing with the endocrine system, its diseases, and its specific secretions called hormones

the integration of developmental events such as proliferation, growth, and differentiation (including histogenesis and organogenesis) and the coordination of metabolism, respirations, excretion, movement, reproduction, and sensory perception dependent of chemical cues, substances synthesized and secreted by specialized cells



the functional tissue of an organ



the connective tissue or framework of an organ

contains blood vessels, nerves, trabeculae, and finer fiberous networks of collagen (reticular fibers) or elastin



part of the stroma; surrounds the gland



part of the stroma; septa

divide glands into loves or lobules



the inner open space or cavity of a tubular organ


exocrine vs endocrine

exocrine release: through ducts
- ex: sweat glands, salivary glands, mammary glands, pancreas, liver

endocrine release: directly into blood vessels or lymph
- ex: adrenal glands, testes, ovaries, pancreas


basic exocrine gland development

(starts the same as endocrine)
1) specific loci in epithelium begin to proliferate
2) dividing cells invade underlying stroma but retain "seperateness" via basal lamina
(differs here)
3) tubular duct system develops
4) remaining cells differentiate into secretory cells


basic endocrine gland development

(starts the same as exocrine)
1) specific loci in epithelium begin to proliferate
2) dividing cells invade underlying stroma but retain "seperateness" via basal lamina
(differs here)
3) connection with the surface is lost
4) secretory cells associate with blood capillaries or sinuses


describe the release of endocrine hormones and the 3 methods of action

hormone diffuses from the extracellular fluid into the bloodstream and then acts as:
endocrine - travels through the body
paracrine - acts on nearby cells/tissues
autocrine - acts on itself


name endocrine organs/glands

hypophysis cerebri - pituitary
epiphysis cerebri - pineal body
pancreatic islets of langerhans

ovaries and testes
gastrointestinal tract


what are the 2 lobes of the pituitary

anterior pituitary - adenohypophysis
posterior pituitary - neurohypophysis


Describe the basic development of the adenohypophysis

1) ectoderm from the rood of the stromadeum (oral cavity) forms Rathke's pouch

2) base of Rathke's pouch constricts, separating it from the oral cavity

3) lumen of Rathke's pouch may persist as the residual lumen

(the AP and PP meet and fuse to form the Pituitary)


Describe the basic development of the neurohypophysis

1) neuroectoderm of the ventral wall of the diencephalon evaginates to form the infundibulum

2) lumen of 3rd ventricle extends into infundibular stalk and persists as the infundibular recess in some species (pig, cat)

(the AP and PP meet and fuse to form the Pituitary)


what are the 2 distinct systems by which the hypothalamus communicates with the pituitary gland

AP - hypophysial portal system
PP - hypothalamo-hypophysial tract


Describe the hypophyseal portal system.

in the hypothalamus parvocellular neurons in secrete hypothalamic releasing or inhibiting factors (prohormones)

which travel down through the portal vein and are released into the paracapillary space in the adenohypophysis (anterior pituitary)

where they trigger release of other hormones that travel out to the body through the vein


What are the parts of the anterior pituitary

pars tuberalis
pars intermedia
pars distalis


What are the parts of the posterior pituitary

infundibular stalk
pars nervosa


Describe the hypothalamo-hypophysial tract

cell bodies of the magnocellular neurons in the hypothalamus produce prohormones and package them into granules with converting enzymes

they then travel down the unmyelinated axons into the neurohypophysis and accumulate in Herring bodies in the pars nervosa until release is stimulated


What are the 2 types of endocrine producing neuron cell bodies in the hypothalamus? What do they produce?

1) supraoptic nucleaus
produces ADH (vassopressin)

2) parventricular nucleus
produces oxytocin


what is generally the largest part of the pituitary gland across species

pars distalis

very vascular contains huge sinusoidal capillaries


residual lumen

embryologic artifact of the Rathke's Pouch


What are the 3 cells types in the pars distalis of the adenohypophysis

1) Chromophobes
- do not stain well
- function unknown; degranulated

2) Chromophil - Acidophils (tan)
- somatotrophs → GH
- lactotrophs → prolactin (PRL)

3) Chromophil - Basophils (blue)
- thyrotrophs → thyroid stimulating hormone (TSH)
- gonadotrophs → FSH / LH
- corticotrophs → ACTH


What is a major marking characteristic of the pars distalis of the anterior pituitary?

huge sinusoidal capillaries


What are cells are found in the Pars Intermedia of the adenohypophysis?

basophilic cuboidal cells
- melanocytes → MSH


What are cells are found in the Pars Tuberalis of the adenohypophysis?

weakly basophilic cells
- function unknown
- do stain weakly for ACTH, FSH, and LH

also large vessels that are part of the hypophyseal portal system


What are cells are found in the Pars Nervosa of the neurohypophysis?

- contain secretory granules
- whispy appearance

- might function as neuroglia


epiphysis cerebri

pineal gland


What is the function of the epiphysis cerebri "pineal gland"

produces melatonin and serotonin


What inhibits melatonin and serotonin production in the pineal gland?


mammals receive information on light indirectly via the retina

parietal eyes are found in some lizards, frogs, lampreys, and fish "third eye" can directly sense light


What are the cell types found in the pineal gland

- neuroepithelial origin; photo receptors in non-mammalian vertebrates
- large round nucleus; acidophilic cytoplasm
- produce melatonin

- interstitial cells
- compressed nuclei; darker cells

Corpora aranacea
- brain sand; Ca deposit
- stains basophilic
- extracellular, increases with age, not considered pathological


Describe the gross anatomy of the thyroid gland

lies on the trachea just caudal to the larynx
lobes may be connected by an isthmus (fused in pigs)


Describe the cell types found in the thyroid gland

follicles lined with follicular cells containing colloid

parafollicular cells between the follicular cells


What does colloid produce? Where?

takes up iodine from the system and produced T3 and T4 in the thyroid gland


Describe the gross anatomy of the parathyroid gland

generally 4 small glands located about the cranial trachea

generally there are 2 internal glands embedded within the thyroid glands and 2 external glands are outside the thyroid tissue


What are the cell types found in the parathyroid gland

cells are arranged in cords
Chief cells → parathormone → increases blood calcium

Oxyphil cells
- hard to find - cytoplasm is stains diff. sort of smooth
- occur in oxen, horses, man
- unknown function but # often increase w/ age


Describe the gross anatomy of the adrenal gland from outside in.

capsule = skin
cortex = fruit
medulla = seed

may be attached or detached from the kidney depending on species


What are the cellular layers of the adrenal gland from the outside in

1) zona glomerulosa (ruminants, primates) / zona arcuata (horses, carnivores, pigs); SALT
2) zona fasciculata; SUGAR
3) zona reticularis; SEX
adrenal medula


Describe the blood supply of the adrenal gland

several major arteries branch into a plexus of arterioles under capsule, then there are 3 systems

1) subcapsular capillary plexus drains in the subcapsular veins

2) cortical blood sinusoids drain to medullary veins

3) medullary arteries from capillary bed in medulla that drains to medullary veins


What are the characteristics zona glomerulosa (ruminants, primates) or zona arcuata? What does it produce?

steroid producing cells; lipid droplets, tubular mitochondria, extensive smooth endoplasmic reticulum

mineralcorticoids (aldosterone) → increases sodium resporption


What are the characteristics zona fasciculata? What does it produce?

characteristic morphology is radially arranged cords of parenchyma cells

cuboidal cells (spongiocytes) → glucocorticoids → cortisol increases blood glucose & acts on the medulla of the adrenal gland


What are the characteristics zona reticularis? What does it produce?

freely anastomosing cells

sex steroids (DHEA); precursor to testosterone and estradiol


What are the characteristics medulla of the adrenal gland? What does it produce?

distinct border between zona reticularis and medulla

chromaffin cells
- modified postganglionic sympathetic nerve cells, regulated by sympathetic ganglion cells and steroids of adrenal cortex
- produce catecholamines, epinephrine, norepinephrine


Describe the gross anatomy of the pancreas

both exocrine (majority) and endocrine

Islets of Langerhans = endocrine cells embedded in exocrine tissue


What are the Islets of Langerhans and what cells do they contain?

the endocrine portion of the pancreas

α-cells → glucagon → increases blood glucose
β- cells → insulin → decreases blood glucose; 75% of Islets of Langerhans

δ-cells → somatostatin → inhibits secretion of glucagon and insulin

F (PP) - cells → pancreatic polypeptide (more abundant in chickens)