Lavriv L. P., Rachuk N. O.

Bukovinian State Medical University (Chernivtsi City, Ukraine)

MORPHOLOGICAL CHARACTERISTICS OF THE ELEMENTS TEMPOROMANDIBULAR JOINT AND OF THE MANDIBLE AS COMPONENTS OF THE PAROTID GLAND BED IN THE FETAL PERIOD OF THE PRENATAL HUMAN ONTOGENESIS

The scientific sources report different data concerning the features of parotid gland (PG) morphogenesis and formation of topography components of the parotid-masticatory area in human embryogenesis [1-3]. Furthermore, the data concerning normal and variant anatomy of the organs and structures of the parotid-masticatory area as well as formation of their correlations during human perinatal growth remains insufficiently studied [4]. The data about the PG syntopy and the histogenesis of the parotid-masticatory area components are disputable and controversial [5-7]. Actually, it is the complexity of topographical and anatomical relations as well as that of histogenesis of the parotid-masticatory area components in human perinatal period which stipulates the need in their further anatomical and histological study.

The object of our research was studying the forming of the PG bed in the fetal period of the prenatal human ontogenesis.

Material and methods of research. The study of the morphological characteristics of the mandible and elements of the temporomandibular joint, as components of the parotid gland bed has been carried out on 28 human fetuses of 130,0-375,0 mm parietal-coccygeal length by fine preparing the PG and parotid-masticatory areas under the control of binocular magnifier, macro and microscopy; morphometry.

Results. It has been established that the PG is located on the face, in a deep recess (the glandular bed) behind the branch of the lower jaw in the retromandibular fossa. The PG bed represents a cavity with three sides the vertical dimension being the largest. The anterior surface of the bed is formed by a branch of the lower jaw and the masseter muscle, covering it (outside) and the pterygoid muscle (inside). The posterior surface of the bed is formed by the posterior belly of the digastric muscle and the styloid process. The interior cervical base of the bed is formed by the interglanular septum (mesenchymal by origin). The superior, temporal base of the bed is formed by means of two clevises: the posterior one – the external auditory meatus and by the anterior one – the temporomandibular joint. The cupola of the bed makes up the skull base along the whole length of the base of the styloid process. Apart of the PG, the external carotid riculotemporal nerves and lymphatic vessels pass in this bed. The syntopy of the PG is complicated, both with the organs, lying outside the glandular bed (internal syntopy).

Fetuses aged 7- months are characterized by very poorly expressed endochondral ossification of the mandible and extremely broad area of cartilage calcification. The significant topographic and anatomical differentiation of the temporomandibular joint is accompanied by significant histological differentiation of its components. In the early fetal period of prenatal growth temporomandibular joint turns into a typical diarthrosis and has all the basic elements of the joint with the tissue ratio, characteristic for the formed area of the temporomandibular joint and which can be clearly seen on the frontal serial histological sections.

In the body of the mandible of 10 month old fetuses there is a well-differentiated spongy osseous tissue, which is usually directed from the alveolar part and alveolar arch of the mandible toward the coronoid process, on the other side - it extends to the angle of the mandible , base of the condylar process and the marrowy canal walls. During this period some solid osseous tissue can be observed in the lower part of the mandibular body, in the coronoid process, in dorso-caudal branch and on the way to to the mandibular neck. The articular disc and the cartilage of the condylar process which are separated by common slits in the temporomandibular joint are well supplied with blood vessels at this stage of growth. It has been proved by this study that, at the end of the prenatal period, the cartilage of the temporomandibular joint (from the articular slit to the bone) has all 5 stratification zones: fibrous layer, intervening zone, chondroblast layer, hyaline layer and ossification zone.

Conclusions. Active application of perinatal prevention of congenital defects requires up-to-date approaches and methods of embryonic growth study. Embryotopographic research, which takes into account specific and critical for some organs periods of their growth and some peculiarities of their interrelations with adjacent organs and structures, becomes especially important. The problem of grounding the critical periods in structural changes of organs and systems, in particular the parotid gland and the temporomandibular joint has not been sufficiently studied and requires further research by means of up-to-date histochemical methods.

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