ABSTRACT
A histochemical study of labial glands was performed to compare the different stages of differentiation with those of lingual glands previously studied. Labial glands of 8 to 32 week old human fetuses were analyzed with Hematoxylin/eosine, PAS, Cason, Alcian blue, Toluidine blue, methenamine/silver, TEM and Ruthenium red techniques. At 8-10 weeks various differentiation phases of cell cords originated in the epithelium of the labial mucosa were observed. Acinar buds had PAS positive, alcianophilic and metachromatic material in the lumen of 14 week labial glands. The excretory ducts featured similar characteristics. At 24 weeks groups of mucous and seromucous acini were identified and the mucosubstances increased in the 32 week old fetuses. These results show that the labial glands are histophysiologically differentiated at an earlier stage of development (14 weeks) as compared to lingual glands (20 weeks). However, mucosubstance production would begin during the early phases of embryogenesis for both labial and lingual glands.
ABSTRACT
Evolutionary, structural, ultrastructural and cytochemical studies (PAS, alcian blue, toluidine blue, Ruthenium red) were performed in chick tongues 7 to 19 days development, with the aim of observing the histomorphological changes during growth and differentiation. At 7 days the tongue was covered by a flat epithelium without cornification, with four cell lines. As an axis was observed a central hyaline-cartilaginous skeleton surrounded by mesenchyma. Since 11 days appeared glandular buds and canalized cell cords united trough complexes. At 15 days the epithelial thickness increased remarkably. The subepithelial connective tissue, already notably differentiated, formed papillae. Glandular acini contained PAS positive, alcianophilic, metachromatic and positive ruthenium red substance. Ultrastructurally, glands showed clear cells, with decreased electronic density and organoids randomly distributed and dark cells having electrodense cytoplasm and more organized organoids. At 19 days the epithelium was cornified in the tongue anterior half. A net increment of glycoconjugates was detected in glands. These observations show: 1) lingual glands secrete mucins since 15 days of embryonic development; 2) the cornified anterior epithelium is the result of a genetic pattern and not of a later functional adaptation to the type of feeding (grain eating birds).
ABSTRACT
The structural and histochemical patterns of the salivary mesenchyma were analysed in relation to the epithelium of the labial glands during the embryonic development to correlate the structural and histochemical characteristics in both tissues during the histogenesis. Samples of human fetal lips were analysed using H/E, PAS, Cason, Alcian blue, Toluidine blue and Methenamine/silver. The process of glandular histogenesis begun between 8 to 10 weeks. The mesenchyma surrounding the glandular buds had PAS positive granulations which were also alcianophilic, metachromatic and periodatoreactive. Periodatoreactive collagenous fibrillae, reticular cells and nervous fibers of considerable diameter were observed. Basement membranes were PAS positive, alcianophilic and discontinuous. At 12 weeks the mesenchyma differentiated as loose connective tissue which produced a delicate periglandular capsule with fibroblast and collagenous fibrillae. From 20 to 24 weeks the acini were structurally and histochemically differentiated as serous, mucous and mixed. It was postulated that the periglandular mesenchyma would play and important role in the morphogenetic process in relation to the histochemical identification of molecules which have a specific biological functions in the epithelium-mesenchyma interactions during organogenesis.