Glands Flashcards
Glands can be classified based on
# of cells in a gland relationship to the surface lining and surrounding tissues
Describe the difference between unicellular and multicellular glands
unicellular
-specialized cells scattered throughout an epithelium
-goblet cells–> respiratory, digestive, urinary tract
Multicellular
-composed of more than one cell
-varying degrees of complexity
Exocrine glands secrete product?
directly onto a surface or through epithelial ducts that are connected to the surface (gut lumen, skin surface)
Describe characteristics of endocrine glands in mammals
-ductless gland system
-high vascularity allows for increased blood flow
-functionally related to nervous system
-
Compare the endocrine and nervous system in terms of:
specificity, speed and response time
E= broad, slower, prolonged response N= specific, fast, short response
Describe the different arrangements of the endocrine gland
follicles- thyroid
cords- adrenal
nests or clumps - parathyroid
The pituitary gland develops from which two structures
Rathke’s pouch- ectodermal evagination of the developing guy (oropharynx)
Neuroectodermal downgrowth of the diencephalon
What is the cleft in the pituitary gland called?
hypophyseal cleft
What are the 3 areas within the adenophysis (endocrine control)
Par distalis pars intermedia -adjacent to neurophysis pars tuberalis -adjacent/surrounding infundibular stalk
What is the infundibular stalk?
reminent from down growth during production
What is the hypothalamohypophseal tract?
will see nerve processes within the infundibular stalk that are neurons from the hypothalamus
How does communication between hypothalamus and anterior pituitary work?
Parvocellular neurons
-neurosecretory cells secrete trophic hormones (releasing factors/hormones) into the hypophyseal portal system of adenohypophysis
Pars distalis
distal part of anterior lobe
- major portion of adenophypohysis
- cells arranged into cords/clusters
- Many capillaries and sinusoids
Chromophiles
like stain
acidophils- red/pink
-pink colour= acidophils produce peptide hormones
Basophils -blue/purple
-glycoproteins produced by these cells that’s why cytoplasm looks purple
Chromophobes
we hate stain
Functional cell types identified with PAS-OG
Acidophils
- somatotroph- secrete growth hormone
- medium, oval/angular, orange cytoplasm prominent nucleoli - mammotroph- secrete prolactin
- large, polygonal/angular, purple-pink cytoplasm
Basophils
- gonadotrophs– secrete FSH and LH
- large, round, granular deep purple black cytoplasm - thyrotrophs
- small,angular, oval nucleus, very dense deep purple-black
Pars intermedia
- narrow band
- close association with pars nervosa
- hypophyseal cleft separates from pars distalis
- basophilic cells arranged in layers
- most are melanotrophs- melanocyte stimulating hormone
Pars tuberalis
- collar around infundibular stalk
- basophillic cells are arranged in clusters/rosettes
- many veins/venules
- gonadotrophs
Magnocellular neurons
- peptidergic neurosecretory cells
- terminate within neurohypophysis–> herring body
- ADH, oxytocin
Pars nervosa
zones of the infundibular stalk
herring bodies
pituicytes (glial cells of pituitary)
Is it easier or harder to see a herring with H&E?
difficult to see herring body
-easier to see with trichome
Thyroid and parathyroid
Bi-lobed in most mammalian species
In general, lobes are connected by the isthmus (also glandular)
Function is essential to normal growth and development
What is the functional unit of the thyroid?
Follicle
What structure of the thyroid can be very thick in ruminants
CT capsule with trabeculae and septa
Follicular cells within the thyroid are
- epithelial cells that form the follicles
- simple cuboidal secretory cells
- microvilli on apical surface (hard to see) - lumen of the follicle filled with colloidal substance (T3 and T4)
- homogenous eosinophillic material
- may see vacuoles
Parathyroid gland
embedded in the thyroid Capsule surrounds the parathyroid -extends within the parathyroid to form trabeculae/septa (white arrows) -dense irregular CT -highly vascularized Chief cells (principal cells) -compose majority of the parathyroid -deeply basophilic and uniform cuboidal secretory cells -parathyroid hormone (PTH)
Oxyphils are common in?
humans, horses, large ruminants
-no known secretory role
What are the 2 regions of the adrenal gland
cortex and medulla
-the adrenal glands are encapsulated by CT
Function of the cortex
steroids
- mineralocorticoids- zona glomerulus - aldosterone
- glucocorticoids- zona fasiculata- cortisol
- Zona reticularis- sex hormones estrogen and androgen
Function of the medulla
catecholamines
- epinephrine (adrenalin)
- norepinephrine (noradrenalin)
Zona glomerulosa/arcuata
first layer under the capsule
species difference in cell arrangement
-glomerulosa- ruminants, pig (clusters or cords with glomerular appearance)
-arcuata- horses, dog (columnar cells arranged in arches)
Zona intermedia
-prominent in horses, ruminants
-transitional zone to undifferentiated cells between z.glomerulosa and z.fasiculata
Zona fasiculata
- most extensive
- spongiocytes
- may appear vacuolated
- cuboidal or polyhedral in shape
- arranged in regular rows/cords
- cords radiate away from medulla
Zona reticularis
- innermost layer adjacent to the medulla
- cells are smaller and arranged in interlacing anastomising cords
- may see sinusoids
Medulla H&E
cells in groups, cords
stellate with round nucleus
faint basophilic cytoplasm
Chromaffin reaction in the medulla
K2Cr2O7- potassium dichromate
oxidizes catecholamines- brown
call chromaffin cells
