On the development of the membranous labyrinth and the acoustic and facial nerves in the human embryo / by George L. Streeter.

  • Streeter, George Linius, 1873-1948.
Date:
[1907]
Catalogue details

Licence: In copyright

Credit: On the development of the membranous labyrinth and the acoustic and facial nerves in the human embryo / by George L. Streeter. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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    List of Embryos Reconstructed. Number of embryo. Length in mm. Probable age in days. Section. n. n. V. B. Thickness. Direction. 148 4.3 3 20 10 a Coronal. B 17 6.5 6.6 26 15 Sagittal. 2 7 6 26 15 Coron-trans. 163 9 9 30 20 Transverse. 109 10.5 11 33 20 Transverse. 175 13 • 13 36 20 Transverse. 144 12 14 37 40 Sagittal. 22 18 20 44 50 Transverse. 229 — 21 44 50 Sagittal. 86 20 30 54 50 Coronal. One or more wax plate reconstructions were made of each, embryo after the method of Born. In most cases the models included the membranous labyrinth with the acoustic and facial nerves, and a portion of the central nervous system. Of these models seven were selected for illustration and are shown in Plates I and II. The form of the models has been controlled in all cases by dissections of pig embryos of cor- responding stages of development, prepared in the manner described in a previous paper (Streeter, 04, p. 87). Such comparison was of particular assistance in the study of the nerves and ganglion masses. The value of these dissections was greatly increased by previously staining the embryos, in toto, with alum cochineal (powdered cochineal 6 gnu, ammonia alum G gm., and distilled water 200 cc.), which produces a brilliant differentiation of the tissues. In the same way that a micro- scopical section is improved by staining so is a stained microscopical dissection that much better than an unstained one. Tn studying these a strong, direct illumination of the specimen is necessary. Whenever the size of an embryo is expressed by a single dimension it refers to its greatest length, and the age is that as determined by Mall’s rule, i. e., age in days equals the square root of the greatest length times one hundred. The drawings for Plates I and II were prepared under the guidance and assistance of Mr. Max Brodel, for which the author derives pleasure in taking advantage of this opportunity to acknowledge his appreciation. Membranous Labyrinth. The auditory organ is generally described as developing phylogeneti- cally from the lateral line organs of the marine vertebrate, which sink beneath the surface of the body and develop a cartilagenous or bony