Endocrine histology

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Histology of glands

ENDOCRINE

CNS

Pituitary

Bony matrix surrounding

Anterior pituitary

No direct nerve cell connection with brain

Develops from roof of mouth

cells

Chromophobes

Smaller

Probably chromophils that have released their contents

Resting

Chromophils

Acidophils

Basophils

Posterior pituitary

Direct nerve cell connection with pituitary

Nuclei belong to support cells

??

Intermediate lobe

Not significant in many species

Pituitary stalk

Connects too hypothalamus

Near

Pineal

Protrusion of roof of 3rd ventricle

Produces melatonin

Levels rise in darkness

Promotes sleep

Seasonality

Nerve connections with hypothalamus + eyes

Neuroglial cells

Pinealocytes

Modified neurons?

Axons make contact with capillaries - releasing melatonin into blood stream

Pineal sand

Function unsure

Deposits of Ca, Mg , Phosphate extracellularly

Resolves with imaging well - good landmark for middle of brain

Tumour cause it to be pushed from midline

Periphery

Thyroid

Spherical units of cuboidal epithelial cells

Follicles

Parafollicular cells

Clustered between follicles

Produce calcitonin

Regulate calcium levels in blood

Parathyroid

V small

Embedded against thyroid glands

Number varies between species

Pared

Chief cells

Small oval cells

Rounded nuclei

Produce parathyroid hormone

Works opposite to calcitonin

Oxyphil cells

Larger

Few of them compared to chief cells

Function unsure

Pancreas

Endocrine + exocrine combined

Islands of endocrine tissue

Islets of langerhans

Synthesise + secrete hormones that regulate carbohydrates

Pale staining

Penetrated by CT

Special staining allows location of cells producing glucagon + insulin

Insulin throughout

Glucagon outer

Adipose tissue

More in older animals

CT penetrates into gland + divides into lobes+lobules

Exocrine

Darkly stained serous tissue

Granular cytoplasm

Enzyme production

EXOCRINE

Mammary

Released through duct

Towards teat ducts merge + increase in size

Continuous with teat

Alveolus , lobule, lobe

Ductules , Larger ducts, Gland cistern, Teat cistern, Teat canal

Milk ejected from teat

Ducts made up of epithelial / cuboidal cells - also produce milk

Alveoli surrounded by mammary epithelial cells ?

Produce milk

Milk protein + fat

Protein released by phagocytosis?

Lipid globules released by exocytosis?

Go from cuboidal to columnar, eject milk then return to cuboidal

Capillary around alveoli

Myoepithelial cells surround alveoli?

Involution if not producing milk

Fibrous interlobular tissue

Thinner looser around alveolii

Adipose tissue

Lactating

Lumens widened

Pink staining substance in lumen

White spaces = lipid dissolved out during staining

Cells flattened

Compound gland

Branching system

Pancreas?!