THERE HAVE been many studies on the vitreous body; yet it is incompletely understood. It undoubtedly plays a large role in ocular pathology and in the complications after ocular surgery. The present study is an attempt to visualize and analyze the physiologic movements of the vitreous during ocular rotations. The anatomic characteristics and relations of the vitreous are difficult to ascertain because of its transparency and its perishable nature. Numerous studies have been made during the past century, the results of which are not uniform; in fact, the conclusions in some respects are rather contradictory and confusing. Best,7who made an outstanding anatomic study nearly 50 years ago, was aware of a relation of the vitreous to retinal detachment, and his concept of the vitreous structure seems to be rather close to that which is presently held. Among the more recent excellent contributions are those of Friedenwald and Stiehler,
To the Editor.—The interesting article by Bonneau and Lehman in theArchives(101:408-412, 1975) has prompted me to write. These authors have listed several theories as to the cause of recurrence at the stoma following laryngectomy. I have seen other theories expressed by other writers, but, with one possible exception, I have seen no reference to what looks to me like an obvious reason for this to occur. Carcinomas of the lung exfoliate malignant cells, which are sought in the mucus for diagnostic purposes. Is it not to be expected that a laryngeal cancer also exfoliates malignant cells? Any malignant cells inhaled by the patient, especially when he is struggling with partial obstruction, and any cells that might reach the lower respiratory tract from manipulation of the lesion during removal or by the use of endotracheal tubes or tracheostomy tubes, on getting down into the tracheobronchial tree will be
(1) A series of changes takes place in the respiratory epithelium in extirpated cow tracheas after a light swab has been passed over the surface. These take place over a period of 1 to 24 hours and are characterized by progressive loosening from one another of the columnar cells and cleavage from the underlying cells, with subsequent loss of cell form and complete exfoliation of the columnar layer. A new surface forms on the remaining cells, giving the appearance of a thin, flat epithelium. (2) During these changes, the epithelium becomes progressively more fragile and even, after just two hours, can usually be wiped away cleanly with a 5-gram swab. (3) The staining of the cells by methylene blue seems to be due to injury of the cell and is not dependent upon the presence or absence of overlying mucin. (4) No definite regeneration of epithelium could be determined in the extirpated trachea, even up to 72 hours, although there were suggestions of it.
