a-short-review-of-histology

The Pancreas:

The pancreas lies within the concavity of the "C" - shaped duodenum (the head of the pancreas) and extends towards the hilus of the spleen (the tail of the pancreas)
The pancreas is both an exocrine gland and an endocrine gland
The exocrine portion of the pancreas forms the bulk of the gland and gives it its overall morphology
There is a thin connective tissue covering of the glands with septae which divide the gland into lobules
There is a central large duct which drains into the duodenum (there may also be an accessory duct which runs in parallel with the main duct)
Divisions of this duct drain lobules of secretory acini
The secretory acini are composed of cells rich in rough endoplasmic reticulum which is located at the basal side of the cell
There are numerous storage granules in the apical cytoplasm
The granules contain a range of digestive enzymes
The endocrine component of the cytoplasm consists of small clusters, or islets, of cells scattered throughout the pancreas
These are known as Islets of Langerhans
There is a greater density of islets in the tail of the pancreas than in the head
The islets have a rich capillary network and in common with other endocrine glands the capillaries are of the fenestrated type
The hormones secreted by the Islets of Langerhans include insulin and glucagon

Questions:

Micrograph of Gall Bladder:

This micrograph shows an area of pancreas containing numerous secretory cells
Most of the cells shown form part of the exocrine pancreas
However, notice that in the middle of the micrograph there is a small, more palely stained cluster of cells
This cluster of cells is an Islet of Langerhans, part of the endocrine portion of the pancreas