THE ELECTRON-MICROSCOPIC STUDY OF THE
CONDUCTING ZONE OF THE LUNG OF BACTRIAN CAMEL
YESSIMSIITOVA Z., BAZARBAYEVA Zh., NURTAZIN S.
Kazakh National University named after Al-Farabi, Almaty, The Republic of Kazakhstan, zura1958@bk.ru
Abstract
The lungs are one of the main organs of metabolism and play a crucial role in the formation of the
species and animal features, as well as in the nature of its constitution and productivity. In this regard,
morphofunctional and electron microscopic study of the lungs with consideration of the ecological and
biological characteristics of species is of great practical and theoretical significance. The aim of this work
is the electron-microscopic study of tracheobronchial wall of respiratory organs of Bactrian camel.
It was revealed that the following cell types are clearly found in the tracheobronchial lung lining of camel:
basal, ciliated, replacement and glandular. Other cell types either take little differentiated immature forms
(indifferent), or very few (endocrine, Clare cell). The ciliated cells are the main type of cells of aeriferous
lining of lungs that provide cleansing of a surface of conductive epithelium. Glandular cells develop in the
bronchial epithelium and in complex tracheo-bronchial glands. Basal and replacement cells have the
ability to differentiate into a variety of divergent cell types. The example of one of the most common ways
of complication of tracheo-bronchial secretion structures is the formation of complex branched
multicellular glands.
Key words: camel, lung, cell types.
Introduction
The respiratory organs play crucial role in the phylogeny of vertebrates. The changes in
respiratory organs lead to the correlative changes of the whole organism. Despite the large number of
articles devoted to the morphological studies of the respiratory system, there is still much uncertainty in
the laws governing the transformation of lungs in a number of terrestrial vertebrates [1-4]. Adaptations
and phylogenetic reconstruction of the respiratory system are accompanied by the establishment of new
trophic, functional, and other topographical relationship between cell populations and tissue systems
lungs. During the evolutionary development the role of animal lungs gradually expanded. As a result the
lungs are not only the organs of the external respiration, but also involved in metabolism in the excretory
processes in thermoregulation, as well as they perform barrier and protective functions. The comparative
morphology of the mammalian lungs in functional terms with respect to ecological and biological features
of animals and species studiedinsufficiently, so is of great scientific interest. The aim of this work is an
electron-microscopic study of the epithelial lining of the camel lung airways.
Materials and methods
The material for the study were light Bactrian camel Camelus bactrianus L.
For electron microscopic examination of tissue slices of the trachea, bronchus and lung parenchyma were
fixed in 2.5% glutaraldehyde solution in the phosphate buffer at pH 7.2-7.4 Milloniga. Additional fixing of
material was made in buffered 1% osmium tetroxide solution, after which the body pieces were poured
into a mixture of Epona and araldita. Ultrathin sections thickness of 40-60nm. were obtained on a
ultramicrotome LKB-III (Sweden), and then they were contrasted with a solution of 2.5% uranyl acetate
and lead citrate according to Reynolds. The study and photographing were carried out using electron
microscope EMB- 100L at an accelerating voltage 75-80kvt.
Results and discussions
Inside the conductive parts of the lungs were lined with high prismatic ciliated epithelium. The following
cell types were identified in its structure: basal, ciliated, brush and mucous secretory.
Basal cells are located at a well-defined basal membrane and fastened thereon by means of
hemidesmosomes. The nuclei are large, with electron-dense patches of condensed chromatin.
Mitochondria are few, polymorphic matrix is with high electron density and with closely located cristae.
The Golgi apparatus is underdeveloped. Tanks and granular endoplasmic reticulum tubules narrow and
long. Many spare ribosomes are identified. Connection with neighboring cells is carried out by means of
desmosomes.
Ciliated cells have cytoplasm average electron density. In the apical section numerous mitochondria with
coated matrix and quite rare Kristen can be identified. Granular endoplasmic reticulum is short, narrow,
sometimes slightly dilated tanks bearing membrane-associated single ribosome. Free ribosomes quite a
lot. On the apical surface numerous cilia can be seen (Figure 1a).
1
1
2
a
b
Figure 1: a) ciliated cell.1- cilia, cut crosswise; 2-ciliated cell cytoplasm;
b) glandular cells. 1- secretory granules in the apical part of the cell.
Replacing cells are much less common than the ciliate. This type of cells characterized by cytoplasm with
high electron density, have numerous mitochondria and rough endoplasmic reticulum tank. On the apical
surface numerous microvilli are found. Occasionally smaller homogeneous secretory granules of serous
or mucoid character can be found in the cytoplasm of cells that indicates a low level of cells
specialization.
Mucous secretory (glandular) cells have columnar elongated shape, can be found several times (3-4) less
than ciliated. They are predominant in recesses of mucosal folds. In the distal airways Mucocytes
gradually reduced. In the cytoplasm of these cell types a great number of large secretory granules are
revealed (Figure 1b).
Thus, the main types of differentiated epithelial cells of the lung airways of Bactrian camel are ciliated,
that provide conductive surface cleansing of epithelium and mucous secretory cells, that protect and
moisturize the conductive epithelium. Also undifferentiated cellular elements at different stages of
development can be found. They have the ability to differentiate into a variety of divergent cell types.
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