Paper - On Ossification Centers in Human Embryos

Embryology - 23 Apr 2024 Expand to Translate
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=On Ossification Centers In Human Embryos Less Than One Hundred Days Old=

By Franklin P. Mall

(Fromthe Anatomical Laboratory Of The Johns Hopkins University.)

With 6 Text figure ansd 7 Tables.

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As the study of the bones preceded that of the other structure of the human body, so their ossification was the first subject investigated in embryology. The early anatomists became interested in the development of bones on account of the difference between them in adults and children, and it was but a step to their study, first in the fetus and then in the embryo.

More than one hundred years ago the early ossifications were studied with vigor and in a short time the subject was closed, and we may say that our present knowledge dates mostly from before 1820. With the improve ment in embryological methods so many new fields were opened that it did not seem worth while to destroy good specimens nor to make laborious reconstructions to study a subject which seemed so unpromising in re sults. However, it is apparent that there is considerable difference of opinion regarding the time of ossification as well as the number of centers in certain bones, which frequently diminish as they are studied more carefully .

We notice in looking over the older literature that the ossification was studied by means of ordinary dissection after which the very small specimens were dried upon a glass slide. Such specimens show sharply marked bone centers, and are very useful, but unfortunately the embryos are pretty well destroyed in their preparation. Furthermore, very small centers and delicate attachments are difficult to see, and this defect in the specimens has led to numerous erroneous conclusions. The time of ossification and the order of the appearance of the centers has never been definitely settled, mainly because the specimens were not numerous and were much injured in their study, and because the various investigators did not determine correctly the age of the embryos. Thus, for instance, we read in Béclard’s article that the centers for the mandible, maxilla, clavicle, humerus, ulna, radius, femur and tibia are present in an embryo 35 days old (16 lines long) which, according to my table, must be 54 days old. Numerous other embryos are studied in this article, each time giving their age in days or weeks, and usually omitting their length. A similar criticism may be made regarding Meckel’s great paper from which is derived our main information regarding the development of the spinal column and skull.^[1]

The older illustrations of primary bone centers are not especially good, for in them the finer details are obscure and the enlarging glass did not aid to make them sharper. However, some of Meckel’s pictures are still used in the anatomies,^[2] but the small dried arms pictured in Bell’s Anatomy^[3]and in Rambaud & Renault’s Atlas^[4] have not been copied extensively. Semidiagrammatic illustrations, i. e., older bones with the earlier centers marked in them have gradually taken their place. And it is only in very recent years that suitable illustrations from X-ray pictures,^[5] from transparent embryos^[5] or from reconstructions^[6] are taking their place.

References

↑ Béclard, Meckel’s Archiv, 1820.
↑ Rambaud & Renault, Origin et Devel. d. Os., Paris, 1864.
↑ Bell’s Anatomy, New York, 1834, p. 66.
↑ Rambaud & Renault, Origin et Devel. d. Os., Paris, 1864.
↑ ^5.0 ^5.1 Schultze, Grundriss d. Entwickl. d. Menschens, 1897.
↑ Gaupp, Hertwig’s Handbuch d. Entwickelungslehre, Jena, 1905; Bardeen, Amer. Journal of Anatomy, IV, 1905.

Mall, F. P. : On Ossification Centers in Human Embryos. The American Journ. of Anat. Vol. 5. 1906. http://onlinelibrary.wiley.com/doi/10.1002/aja.1000050403/abstract

Cite this page: Hill, M.A. (2024, April 23) Embryology Paper - On Ossification Centers in Human Embryos. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Paper_-_On_Ossification_Centers_in_Human_Embryos

What Links Here?

[1] Béclard, Meckel’s Archiv, 1820.

[2] Rambaud & Renault, Origin et Devel. d. Os., Paris, 1864.

[3] Bell’s Anatomy, New York, 1834, p. 66.

[4] Rambaud & Renault, Origin et Devel. d. Os., Paris, 1864.

[Schultze1897-5] 5.0 ^5.1 Schultze, Grundriss d. Entwickl. d. Menschens, 1897.

[6] Gaupp, Hertwig’s Handbuch d. Entwickelungslehre, Jena, 1905; Bardeen, Amer. Journal of Anatomy, IV, 1905.

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