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The time of appearance, morphology and topographic distribution of gastrin/CCK-, somatostatin-, 5HT-, and bombesin-like immunoreactive cells during embryonic and postnatal development were studied in chicken antrum and duodenum with immunohistochemical methods. Gastrin/CCK-like cells appeared on or about the 11th day in the antrum and duodenum, somatostatin-like cells around the 12th day in the antrum and the 11th day in the duodenum, bombesin-like cells appeared only in the antrum and only at hatching. In the early stages of development all the immunoreactive cells were localized in the surface epithelium, descending deeper into the glands as these form, although some cells could always be seen in the surface epithelium. Around the 17th day the number of gastrin/CCK-like cells and somatostatin-like cells in the antrum increases, while 5HT-like already become more numerous in the duodenum from the 13th day onwards. Two territories were recognized in the antrum of the adult: the first was near the duodenum where gastrin/CCK-like and somatostatin-like cells, often in close contact, were very numerous; the other territory was near the gizzard where bombesin-like cells were more numerous. Both regions contained 5HT-like cells in smaller number. In adult duodenum, 5HT-like cells were the most numerous, while somatostatin-like cells and gastrin/CCK-like cells, found in more superficial locations, were more scanty.

Immunoperoxidase methods were used to reveal Sauvagine-Like immunoreactivity (SVLI) in the urophysis and whole caudal neurosecretory system of fresh water fish Tinca tinca and Salmo gairdneri L. Both Dahlgren cell cytoplasm and axons, which reach the urophysis, were filled with SVLI granules. The urophysis shows: a) in the medullary zone, several SVLI Dahlgren cells and a thick network of SVLI axons; b) in the cortical zone, a series of complicated neurohemal knots where SVLI axonal endings surround and penetrate the capillary and glial cell networks. An individual variability and the possibility of a release of SVLI material into the cerebrospinal fluid were also demonstrated. These observations further suggest that, besides the biological effects, sauvagine and the urophysial substance urotensin I, may also have a similar structure.

The distribution and morphological behaviour of bombesin like immunoreactive cells in the proventriculus of chick embryos, newborns and adults were investigated by indirect immunoperoxidase procedure. The first immunoreactive cells appear around the 11th day of incubation. Initially few, they increase progressively to reach a peak around the 18th day. Throughout the embryonic period almost all immunoreactive cells are column-shaped, display a typical "open" behaviour, and are situated among other superficial lining epithelial cells. Around hatching time, these "open" cells suddenly decrease in number while another immunoreactive "closed" cell type becomes more evident in a deeper location. In newborns and adults, the majority of immunoreactive cells are oval shaped and are characteristically situated near the neck of lobular glands; they seem to display a "closed" behaviour. The results demonstrate two different kinds of peptide-containing cells which probably exert different functions. During the embryonic period, in fact, they resemble a chemioreceptor, but in postnatal life they appear as a paracrine/endocrine elements.

By using a double-stain immunohistochemical procedure, the Aa. studied the onset, the behaviour and the possible interrelationship between the 5-HT-like and bombesin-like immunoreactive cells during the ontogenesis of chicken proventriculus and in adult animals. The 5-HT-like immunoreactive cells become evident from the 8th day of incubation and they reach their peak around the 16th day, then markedly decrease at hatching. In adult animal these cells are always present, but are not so numerous. Between the 14th and the 18th day many double-stained cells scattered among other only 5-HT or bombesin-like immunoreactive cells are present. They can also be observed in adults, but only occasionally.

The AA. have studied the effect of the bovine GH on the cellular and intercellular components of the chick embryo tibias cultured organotypically. They have observed a strong increase of the proliferative activity of the chondroblasts such as showed by a stronger uptake of the tritiated timidine by traited tibias in comparison with the control tibias. The chondroblasts of the traited tibias show an increase of some enzymatic activities connected with the aerobic cycle and of the UDPG-DH, connected with the uronic acids cycle. In the amorphous matrix of the traited tibias they have showed a greater polimerisation and sulfation of the condroitinesulfate A and C, which, almost exclusively, constitute the mucopolisaccharidic component of the matrix.

The AA. describe an endocrine cells presence in the Pig Brunner's duodenal glands by means of histochemical methods at light microscope. Between these they can recognize two types of cells: these enterochromaffins (EC) and these non-enterochromaffins (non-EC), both presents either in the secretory part of the glands or in the deeper parts of the ducts. The EC-cells show generally a prismatic size and their apical part attains the glandular cavity. Their granules are much numerous and recognizables either in the basal part or in other parts of the cells. The non-EC-cells show a variable, from the prismatic to the spheroidal, size. Their granules are numerous and recognizables mostly in the basal part of the cells. Between the non-EC-cells they can also differentiate at least three types: a) these Davenport-positives and poorly argyrophils; b) these Davenport-positives and clearly argyrophils and c) these Davenport-negatives and clearly argyrophils. All cells are by lead-haematoxylin stainables, while by the HCL-BT method the EC-cells are ortochromatics and these non-EC are metachromatics.

The study of neuropeptides represents an appropriate playground for comparative and evolutionary research. Comparative analysis can give insight into the conservative pattern of intercellular transmission molecules, possibly bound both to some evolutionary antiquity and to cellular constraints. In the same time it can teach us how modulation has occurred at molecular, cellular, multicellular levels in order to give the species-specific functional organization. Using some examples from vertebrate central neurons system (CNS) immunocytochemical analyses, the results so far obtained suggest the rise of a new comparative chemical neuroanatomy. The rationale of "what" and "why" we are comparing is, however, needed in order to understand constancy, heterogeneity or else trends toward complexity in the distribution of neuropeptides.

Studies on some enzyme activities as measured histochemically in the ligated common bile duct rat liver are reported. They show principally: an increased GGT reaction in the neoductular cells; a diffusion of the LAP reaction to the neoductuli; an immediate increase and diffusion of the alkaline phosphatase reaction; an increase of G-6-PA and AMPA reactions; an increase, during the first week, of the Phyla activity and a contemporary decrease of the UDPG-GS reaction. No significant changes have been observed in other enzyme activities. By means of some dehydrogenase reactions, morphological evidence that the hepatocytes may be involved in neoductular cells formation was obtained.