APUD cells

Endocrine-like cells with biochemical characteristics of Amine Precursor Uptake and Decaboxylase (APUD) were quantified in the tracheal, bronchial, and bronchiolar epithelia of the guinea pig by four histochemical stains Grimelius, en-block silver, lead-haematoxylin-en block silver and periodic acid-Schiff-lead haematoxylin (Marchevsky et al. 1983). There were significant differences between the number of epithelial cells in the various locales of the respiratory tree 318 5.63 epithelial cells/ mm in the trachea, 263 17.11 epithelial cells/mm in the bronchi and 193 4.21 epithelial cells/mm in the bronchioles. Boers et al. (1996) did not find any difference in the number of neuroendocrine cells between large (airway diameter 4.5 mm) and small (airway diameter 1.2 mm) conducting airways in 9 human subjects without pulmonary disease out of 250 autopsy cases. 

In the Wistar rat, there was a decrease in the percentage of bronchi containing Feyrter cells with increasing age (Moosavi et al. 1973). At the age of 7 days, 89 % of the bronchi of one rat contained Feyrter cells, but at the age of 31 days only 45 % of the bronchi of another rat contained such cells. 

Normally there is no proliferative activity in neuroendocrine cells (Hoyt et al. 1990, Montuenga et al. 1992), although this may not be absolute (Stahlman and Gray 1984). 

At the age of 4 days there was no significant difference between the number of Feyrter cells in hypoxic (380 mm Hg simulating an altitude of 5,488 m) Wistar rats and controls (Moosavi et al. 1973). 

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Small blood constituents formed from APUD cells which are involved in blood clotting. Platelets are also called thrombocytes. 

PIT cells were first demonstrated in the sinusoidal wall in rats (E. Witte et al., 1970). Later on, these lymphocytes with large granules and rod-cored vesicles were also found in the human liver, particularly in the sinusoids and in Disse s space. Due to their pseudopodia, they are variable. The proportion of PIT cells to Kupffer cells is 2 10. They are natural killer cells and destroy tumour cells or foreign cells as well as necrosed cells. It is not clear whether they have any additional endocrine function. Because of the strongly polarized distribution of their granulae, they could justifiably be classified as APUD cells. (6, 26, 27, 59, 68, 75)... 

The organization of the endocrine system can best be described in relation to the central nervous system. Three levels of endocrine tissues can be distinguished on the basis of their association with the central nervous system (Figure 30-12). The first level consists of those that are (or were) derived from nerve cells these include the hypothalamus, adrenal medulla, thyroid C-cell, and gastrointestinal enterochromaffin cells. The hypothalamus and adrenal medulla still retain their neural connections and can therefore be regarded as endocrine extensions of the nervous system. The C-cell and the gut cells, however, are APUD cells and lack neural connections. These four tissues produce hormonal peptides or amines having, like neurotransmitters, rapid-onset, short-term effects. 

Gastrin 17 Gastrin-17 G cellsin stomach, duodenum Appetite regulation Gastric acid secretion viahistaminerelease from APUD cells in gastric mucosa (enterochromaffin-like (ECL) cells) (Hj antagonist-sensitive)... 

The follicle cells, called thyrocytes, produce the thyroid hormones and are derived from the entodermal pharynx. Interspersed between follicles are specialized APUD cells derived from the neural crest, called C-cells or parafollicular cells. These cells produce calcitonin (CT), a polypeptide hormone discussed in Chapter 37. 

A patient with an organic hypoglycaemic syndrome, due to a metastatic apud cell eareinoma of the panereas, who was taking streptozocin 2 g daily with phenytoin 400 mg daily for 4 days, failed to show the expected response until the phenytoin was withdrawn. It would seem that tiie phenytoin inhibited the effeets of the streptozoein by some meehanism as yet unknown. Although this is an isolated case report its authors reeommend that eoneurrent use should be avoided. 

CftjHsgNigOijS, Mr 1347.64, crystals from aqueous acetic acid as the triacetate tetrahydrate, [a S -76° (5% acetic acid), a peptide hormone produced in APUD cells (from amine precursor uptake and decarboxylation) of... 

APUD cells are descended from an ancestral neuron although the axon has been lost, innervation is still possible via synaptic terminals, or nervous control may be indirect. Six modes of APUD cell expression are recognized neurocrine (into neurons), neuroendocrine (via axons), endocrine (into the blood stream), paracrine (into the intercellular space), epicrine (into somatic cells), and exocrine (to the exterior). 

Table 23. Pulmonary APUD cell proliferation induced by toxicants ...

Polypeptide Secreting Endocrine Cells (the APUD Series) Cytochemical Characteristics of Polypeptide Hormone-Secreting Cells of the APUD Series Ultrastructural Characteristics of Polypeptide-Secreting APUD Cells ... 

A great deal of work using LeDouarin s method proved that C cells of the thyroid gland and of the ultimobranchial body, type 1 cells of the carotid body, and adrenal medullary N and NA cells are derived from the neural crest. Pearse admitted that the APUD cells of the stomach, intestine, and pancreas are beyond doubt not derived from the neural crest. Instead, they come from neuroendocrine programmed ectoblast. ... 

Pearse AGE, Polak JM. Neural crest origin of the endocrine polypeptide (APUD) cells of the gastrointestinal tract and pancreas. Gut 12 783-788, 1971 idem. Cytochemical evidence for the neural crest origin of mammalian ultimobranchial C cells. Histochemistry 27 96-102, 1971 Polak JM, Rost FWD, Pearse AGE. Fluorogenic amine tracing of neural crest derivatives forming the adrenal medulla. Gen Comp Endocrinol 16 132-136, 1971. 

Pearse AGE, Polak JM, Rost FWD, et al. Demonstration of the neural (APUD) cells in the avian carotid body, using a cytochemical marker system. Histochemistry 34 191-203, 1973. 

The G Cell, 233 G Cells in Disease, 234 Multiple Endocrine Adenomatosis, 235 The A PUD Concept, 236 A Common Origin for APUD Cells , 236... 

NET cells are characterized by their ability to take up and concentrate amine precursors such as dihydroxy-phenylalanine (DOPA) and hydroxytryptophane (HTP) and to produce amines and peptides, for which reason they were also classified as amine precursor uptake and decarboxylation (APUD) cells. They may also express different peptide hormone receptors (like somatostatin receptors) or transporters at their cell membrane. These uptake mechanisms and the presence of peptide receptors and transporters constitute the basis for the use of specific radiolabeled ligands for imaging of neuroendocrine tumors. 

Pearse (60) reported that type I cells of the carotid body resemble the amine precursor uptake decarboxylation (APUD) cell system and suggested that they secrete a polypeptide, provisionally named glomin, that could be important in chemoreception. Now it is well recognized that carotid bodies express a variety of peptides that serve as transmitters or modulators elsewhere in the nervous system (Table 1). 

Sindhu GS. The endodermal origin of digestive and respiratory APUD cells. Am J Pathol 1979 96 5-20. 

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