Book - A textbook of histology, including microscopic technic (1910) Special Histology 10

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Böhm AA. and M. Von Davidoff. (translated Huber GC.) A textbook of histology, including microscopic technic. (1910) Second Edn. W. B. Saunders Company, Philadelphia and London.

A Textbook of Histology (1910): Introduction To Microscopic Technic | General Histology | I. The Cell | II. Tissues | Special Histology | I. Blood And Blood-Forming Organs, Heart, Blood-Vessels, And Lymph- Vessels | II. Circulatory System | III. Digestive Organs | IV. Organs Of Respiration | V. Genito-Urinary Organs | VI. The Skin and its Appendages | VII. The Central Nervous System | VIII. Eye | IX. Organ of Hearing | X. Organ of Smell | Illustrations - Online Histology
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Special Histology

X. The Organ of Smell

The nasal cavity consists of the vestibule, the respiratory region with the accessory cavities, and the olfactory region.

The vestibule is lined by stratified squamous epithelium. In the region of the anterior nares are hairs, the sebaceous glands of which are markedly developed, while at the level of the cartilage mucous glands are also present. The stratified squamous epithelium ceases at the anterior end of the inner turbinate bone and at the inferior nasal duct.


The respiratory region possesses a simple pseudostratified, ciliated epithelium having two strata of nuclei and provided with goblet cells ; the direction of the ciliate movement is toward the posterior nares. Numerous leucocytes are usually found in the epithelium and in the underlying mucosa. Branched alveolar glands, having mucous and serous alveoli, are here present. Within the mucosa are highly developed vascular plexuses, more especially of a venous character. The accessory cavities are likewise lined by ciliated epithelium, the ciliate movement being directed externally.


The olfactory region is principally confined to the superior turbinate bone and to the nasal septum lying opposite, although in the immediate vicinity of the olfactory region a few small islands of the same epithelial type are found, either entirely isolated or connected with the principal region by narrow bridges. In a fresh condition the olfactory region may be differentiated from the surrounding tissue by its color, which is distinctly yellow in man. Its pigment is contained within the sustentacular cells described on the next page.


The epithelium of the olfactory region is of the columnar pseudostratified type, with several strata of nuclei, and consequently closely simulates a stratified columnar epithelium. Here we distinguish olfactory cells and sustentacular cells.

The olfactory cells occupy a peculiar position among the cells of special sense in that they represent true ganglion cells (Schultze, Golgi, Ehrlich, Ramon y Cajal). Within the epithelial layer they appear as spindle-shaped cells, with a spheric nucleus provided with a large nucleolus lying in the thickest portion of each cell. The nuclei of the different cells lie at varying levels in the middle stratum of the epithelial layer. Toward the nasal cavity, the cells terminate in blunt cones, upon each of which are several stiff hairs, the olfactory hairs. The basilar ends form true centripetal nerve-processes, neuraxes, which end in the peculiar telodendria constituting the glomeruli of the olfactory bulb. (See p. 422.)


The nuclei of the sustentacular cells are more oval and are situated at nearly the same level. These cells present the appearances of long columnar cells, which toward the basement membrane terminate in one or several processes. Between the basilar ends of these cells we find a layer of elements the broad nucleated bodies of which rest on the basement membrane, while their upper extremities terminate in short superficial processes.

The mucosa contains a large number of leucocytes as well as numerous branched tubular glands, the so-called olfactory glands or the glands of Bowman. In man these are albuminous (serous) glands, and their cells sometimes contain pigment.



Fig. 377. Portion of transverse section of the olfactory region of man; X I 5 ' *> zone of olfactory hairs ; ep, epithelium ; 2, zone of oval nuclei ; j, zone of round nuclei ; gl, olfactory or Bowman's glands; n, branch of olfactory nerve; tp, mucosa or tunica propria with blood-vessels (Sobotta, "Atlas and Epitome of Histology").


Jacobson's organ consists of blindly ending tubes, situated at the lower portion and at the outer side of the nasal septum. It is lined by an olfactory mucous membrane and receives a branch of the nasal nerve. This organ is rudimentary in man.

The capillaries spread out immediately beneath the basement membrane of the epithelium. In the submucous connective tissue, we find a relatively well developed vascular plexus, rich in venous vessels ; this plexus is especially marked at the posterior portion of the inferior turbinate bone, forming here a tissue which resembles erectile tissue.


A dense network of lymphatics ramifies throughout the mucous membrane, carrying the lymph to the pharynx and palate. These lymph-vessels may be injected through the subarachnoid space (Key and Retzius).

The nerves (trigeminal) are widely distributed in the epithelium, ramifying through both the respiratory and olfactory regions. After repeated divisions these nerves lose their medullary sheaths, and end in telodendria which are usually provided with terminal nodules, although some are found which end in mere filaments.


Technic

The nasal mucous membrane is fixed in situ with osmic acid or one of its mixtures, after which small pieces are removed. It should be mentioned that the nonmedullated fibers of the olfactory nerve assume a brownish color under this treatment, while the fibers of Remak do not (Ranvier, 89).

In order to isolate the epithelial elements, pieces of the mucous membrane are treated with the y$ alcohol of Ranvier. But since the prolongations of the olfactory cells (neuraxes) shrivel and curl in this fluid, Ranvier recommends that, after the epithelial cells have been macerated in ^ alcohol for one or two hours, they be treated with i <f c osmic acid for a quarter of an hour. If shreds be now placed in water and teased, the cells, together with their prolongations, may be isolated without the curling of the latter.

The chrome-silver method applied to the nasal mucous membrane of young animals and fetuses has been the means of establishing the important fact that the olfactory cells of the olfactory region are in reality peripherally situated ganglion cells.


Historic Disclaimer - information about historic embryology pages 
Mark Hill.jpg
Pages where the terms "Historic" (textbooks, papers, people, recommendations) appear on this site, and sections within pages where this disclaimer appears, indicate that the content and scientific understanding are specific to the time of publication. This means that while some scientific descriptions are still accurate, the terminology and interpretation of the developmental mechanisms reflect the understanding at the time of original publication and those of the preceding periods, these terms, interpretations and recommendations may not reflect our current scientific understanding.     (More? Embryology History | Historic Embryology Papers)
A Textbook of Histology (1910): Introduction To Microscopic Technic | General Histology | I. The Cell | II. Tissues | Special Histology | I. Blood And Blood-Forming Organs, Heart, Blood-Vessels, And Lymph- Vessels | II. Circulatory System | III. Digestive Organs | IV. Organs Of Respiration | V. Genito-Urinary Organs | VI. The Skin and its Appendages | VII. The Central Nervous System | VIII. Eye | IX. Organ of Hearing | X. Organ of Smell | Illustrations - Online Histology

Reference: Böhm AA. and M. Von Davidoff. (translated Huber GC.) A textbook of histology, including microscopic technic. (1910) Second Edn. W. B. Saunders Company, Philadelphia and London.


Cite this page: Hill, M.A. (2020, October 24) Embryology Book - A textbook of histology, including microscopic technic (1910) Special Histology 10. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Book_-_A_textbook_of_histology,_including_microscopic_technic_(1910)_Special_Histology_10

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