Paper - On the Development, Ossification, and Growth of the Palate Bone of Man

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Fawcett E. On the development, ossification, and growth of the palate bone of man. (1906) J Anat Physiol., 40(4);400-6. PMID 17232695 | PMC1287457

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This historic 1906 paper by Fawcett describes the development of the human palate.

See also:

Edward Fawcett Links: 1906 Palate | 1910 Head | 1910 Sphenoid | 1911 Maxilla, vomer, and paraseptal cartilages | 1913 Clavicle | 1930 Mandible | Fawcett image | Edward Fawcett


Links: Skull Development | Endocrine - Pituitary Development | Professor Minot | Harvard | Professor Bryce | Fawcett - Head of a 30mm Embryo | Fawcett - Development of the Human Palate Bone | Fawcett - Development of the Human Sphenoid | Embryology History
Links: Skull Development | Professor Bryce | Fawcett - Head of a 30mm Embryo | Fawcett - Development of the Human Sphenoid | Embryology History
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Pages where the terms "Historic Textbook" and "Historic Embryology" 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 and interpretations may not reflect our current scientific understanding.     (More? Embryology History | Historic Embryology Papers)
Edward Fawcett
Edward Fawcett (1867 - 1942)

On the Development, Ossification, and Growth of the Palate Bone of Man

Read before the Anatomical Society, January 19, 1906.

By Edward Fawcett, M.B. Edin., Professor of Anatomy, University College, Bristol.


Palate Links: palate | cleft lip and palate | cleft palate | head | Category:Palate
Edward Fawcett Links: 1906 Palate | 1910 Head | 1910 Sphenoid | 1911 Maxilla, vomer, and paraseptal cartilages | 1913 Clavicle | 1930 Mandible | Fawcett image | Edward Fawcett


Historic Disclaimer - information about historic embryology pages 
Mark Hill.jpg
Pages where the terms "Historic Textbook" and "Historic Embryology" 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 and interpretations may not reflect our current scientific understanding.     (More? Embryology History | Historic Embryology Papers)

THROUGH the kindness of Professor Minot of Harvard, I am able to present the result of an investigation on the above subject. I have been fortunate enough to have from him a human embryo of 19 mm in length, in which the palate bone is just commencing to ossify. I have also from Professor Minot other embryos in which ossification is further advanced, and some material supplied to me by former pupils has enabled me to complete what it is necessary to do by aid of the microscope.


When one looks into the various accounts given by different text-books on the subject, it is, I think, evident that the matter is worthy of further consideration. It is true there is perhaps greater unanimity with regard to the ossification of this palate bone than in the case of many others, but the fact still remains that the accounts are still sufficiently at variance to justify the statement that the matter is by no means setled.

Where the various statements are taken from I cannot say, as no references are given, save in the case of Rambaud and Renault.

Cruveithier, p.72, English edition, 1841, says the bone is developed from a single centre of ossification, which appears from the fortieth to the fiftieth day at the point of union of the vertical and horizontal portions and the pyramidal process. During its development the bone appears as it were crushed down, so that the vertical portion is shorter than the horizontal, and there is a marked predominance in the antero-posterior diameter.
Gray, sixteenth edition, says the bone is developed from a single centre which appears about the second month at the angle of junction of the two plates of the bone. From this point ossification spreads inwards to the horizontal plate, downwards into the tuberosity, and upwards into the vertical plate.

Some authorities describe the bone as ossifying from four centres: one for the tuberosity and portion of the vertical plate behind the posterior palative groove: a second for the rest of the vertical and horizontal plates; a third for the orbital, and a fourth for the sphenoidal process (this is evidently from Ramnbaud and Renault). Int the foetus the horizontal plate is much longer than the vertical; and even after it is fully osified, the whole bone is at first remarkable for its shortness.

Gregenbaur (French translation by Charles Julin, 1889), says: JDe mneme que le maxillaire superieur, le palatin apparait apres la huitie'me seniaine; toutefois ses rapports de situation sont unI peu dif'rents.
Thomson (Cunninghams Text-Book of Anatomy) states that " the palate bones are developed from the ossification of the membrane covering the sides of the oral cavity. According to Rainbaud and Renault, two primitive centres appear about the sixth week of fetal life. From one of these the tuberosity and the part of the vertical plate behind the posterior palative groove is developed; from the other the remainder of the bone is formed, with the exception of the orbital and sphenoidal processes, which are developed from secondary centres that make their appearance somewhat later. Other authorities describe the bone as ossifying from a single centre which appears about the end of the second month in the angle between the vertical and horizontal plates. At birth the bone is much longer in its antero-posterior diameter than in its vertical height, the converse of its typical adult form."
Sappey (fourth edition) says:"Le palatin a pour origine un seul point d'osificatiomnqueoccupel'angle dere union deses deux portions. La portion horizontales' accroit plus rapide imientetl'emported'abordsur laverticale. Plus tard, cette derniere s'allonge un peu; il s'etablit alors lune et l'autre tine sorte d'egalite. Lorsque leserins maxillaire s'agrandit, on voit ha portion verticales' allongeraussietdevenir predoininante."
Testat is content with quoting the account given by Rainbaud and Renault.
Quain (tenth edition) says the palate bone is ossified from a single centre, which appears in the seventh or eighth week at the angle between its horizontal and vertical parts.
Macalister (p. 239) says the palatine bone is formed in a part of the pterygo-quadratecartilage,andisveryirregularandvariable. Itossifies by a single centre which appears at the front of the pyramidal process inl theseventhweek.
Humphrey is very accurate, as a rule, when describing the ossification of a bone. With reference to the palate bone he says (p.296): 'Each palate bone is developed from one nucleus which appears between the fortieth day and the third month, at the angle of union of the horizontal with the vertical portion. The palatine process soon shoots inward to meet that of the opposite side. In the young child the bone has very little depth;the transverse measurement is greater than the vertical, and the orbital portion is not yet formed."

Personal Observations

Sections of various embryos have been examined,some from my own collection, but many from that of Professor Minot of Harvard.

Examination of coronal sections of a 19 mm embryo. These were examined and drawn serially, and it will be noticed that the two opposite halves of the palate P. are at this stage vertically disposed at the side of the tongue T., some distance above what might be expected to represent the point where the angle will be formed. Between the side of the naso-pharynx and the palate, one sees, just commencing to ossify, the palate bone P.B., and it is evident that this centre, as generally described, arises in membrane. Immediately to its outer side can be seen a large nerve clump caused by the palatine nerves. All other sections of this embryo show the same thing, viz., that the palate bone is ossified just internal to the palatine nerves, and therefore in its vertical plate, ossification commencing in the 19 mm embryo. There is as yet no sign of a horizontal plate.

Fawcett1906 01.jpg Fawcett1906 02.jpg
Fig. 1. P.B., palate bone; P.N., palatine nerves; P., palate hanging down by side of tongue, T. Harvard collection, No.819, sect.284. Coronal 19 mm embryo. Fig.2. P.B., palate bone, just developing palatine process; P.,palate, now separating tongue from base of skull; P.N., palatine nerves. Harvard collection, No.24, sect. 378. Coronal 24 mm embryo.

In an embryo of 24 mm in length, also supplied by Professor Minot, one sees the two halves of the palate now horizontally disposed,where as it will have been noticed that they lie vertically disposed by the side of the tongue in the embryo of 19 mm.


It is at this stage that the horizontal plate of the palate bone commences to form, but it does not come of sharply-almost at right angles - as yet; it curves inwards quite at the lower end of the vertical plate, see fig. 2 (Harvard, 24, x. 378). P.B. is the palate bone, P. the palate, P.N. palatine nerves.


At a later stage, however, the direction is much more at right angles to the vertical plate. At no time can any extra centre of ossification be seen. It is true that by making, say, one or two sections either in the horizontal or the vertical direction, one may see what appear to be two centres; but that appearance is due, in one region at all events, to perforation of the bone by an artery from the posterior palatine to the inferior meatus and turbinated bone. This foramen seems to be constant, and in early fetal life is of great size (figs. 3 and 4).

Fawcett1906 03.jpg Fawcett1906 03a.jpg
Fig. 3. P.B., palate bone; G.,groove for internal pterygoid plate; H.P., hamular process; P.N., palatine nerves; P.P.A., post-palatine artery. The bone seems here to consist of two separate parts due to foramen. Fig. 3A. H.P.P., horizontal plate of palate bone; T., tuberosity; H.P., hamular process (cartilaginous); T.P., tensor lIalati; E.T., Eulstachianl tulbe; U.P., coronoid process- N., neck of jaw; MI., malar bone;*S.M., superior maxilla, E., vertical plate of ethmoid; J.C., Jacobson's cartilage. Own collection, M2. Horizontal 42 mm embryo.

It may be taken as conclusive that there is only one centre for the general mass of the bone. But what about the orbital and sphenoidal processes? are they ossified separately or by extension from the general mass?

Fig. 5 is a representation of a section cut sagittally, which I was lucky to get,and it shows at a very early period al thhe essential parts of the palate bone. The embryo from which this series of sections was cut was about 40 mm. in length, but was unfortunately not in the best of preservation and only the bone stained really well, neither nerves nor teeth being stained to any extent. In it one can see the palatine shelf, the maxillary process, and then, quite on the top of the vertical plate, forward and backward projections which indicate the positions of the future orbital and sphenoidal processes. Naturally no spheno-palatine notch is developed, but there is a slight depression on the upper border of the vertical plate which may be taken as representing it (figs.5 and 6.)


In course of time both the sphenoidal and orbital processes develop as outgrowths from the vertical plate, not by separate ossification, and it is to be remarked that at quite an early stage and until birth even the sphenoidal process is much larger than the orbital one; in fact the orbital process appears not unlike a slender coracoid process of the scapula at this time (fig. 7, a and b), directed upwards and forwards at first and being largely maxillary in surface; then it turns suddenly upwards and backwards, being mainly orbital. This disparity in size of the two processes is interesting as leading us back to what holds good with the quadruped palate bone. In a specimen three years old the two processes are about equal in bulk, whilst at the sixth the orbital has quite taken the lead.


Fawcett1906 04.jpg Fawcett1906 05.jpg
Fig. 4. P.B, palate bone; G.P.N., great palatine nerve; P.P.A., post- palatine artery. Own collection. Horizontal, above last, 42 mm. embryo. Fig. 5. O., orbital process; S., sphenoidal process, T., tuberosity of palate bone; H.P., hanmular process; P.M., pre-maxilla; S.M., superior maxilla; N.C., nasal cavity. Own collection. Sagittal, 40 mm, No. 207.

There is another feature of interest at quite an early stage and continued into childhood, that is,the enormous relative size of the groove for the internal pterygoid plate. In all my specimens from the 42mm embryo onwards. this groove is relatively enormous in size (fig. 3, G).


It is a well-known fact that in the fetal life the antero-posterior extent of the vertical plate is greater than the vertical (fig. 5).

These are the leading features of the ossification and growth of the palate bone put somewhat discursively. I will now put them a little more concisely.

  1. The palate bone is developed by membranous ossification taking place at the side of the nasal cavity and immediately internal to the palatinenerves. There is no pterygo-quadrate cartilage in man, so it cannot ossify in that.
  2. Ossification commences in the vertical plate in embryos of some 19 mm. in length.
  3. The palatine process appears in the 24 mm. embryo, at which time the two halves of the palate have become horizontal.
  4. The orbital and sphenoidal processes are outgrowths from the vertical plate, and appear much later. Since the above was written, I have had evidence that the whole of the orbital process may not be formed by upward extension from the vertical plate. As in one specimen of the 2nd-3rd year, the orbital process of the right palate bone has a fissure running right through it at the junction of the lower-with the upper 2. This fissure separated off a small mass which synostosed behind with the body of the sphenoid and the sphenoidal turburated bone and in front with the ethmoid. On the opposite side the corresponding mass was fused with the ethmoid, the orbital process of the palate bone was small, whereas the lateral mass of the ethmoid was much longer on that side than the other. If we regard this mass as the epiphysis which Rainbaud and Renault have described, then it raises the interesting question as to what is its morphological position. That point, I think, may well be deferred for a later paper on in the question. See fig.8.
  5. The sphenoidal process is throughout fiftal life larger than the orbit alone.
  6. Up to, say, about the second or third year, the antero-posterior length is greater than the vertical height of the palate bone.
  7. The groove for articulation with the internal pterygoid plate is enormously larger than the other grooves on the tuberosity.
  8. Chronologically the palate bone appears after the upper jaw, and is therefore third in date of appearance of the skull bones.
Fawcett1906 06.jpg Fawcett1906 07.jpg
Fig. 6. S.P., splhenoidal; O.P., orbital process of palate bone; M.G., Merkel's ganglion; S.P.A., spheno -palatine artery; N.C., nasal cavity. Own collection,same embryo as figs. 4 and 5. Fig. 7. a, seven-month palate bone showing small orbital process; b, younger palate bone than a, and showing a foramen in the vertical plate; c, showing groove for internal pterygoid plate.

Fawcett1906 08.jpg

Fig. 8. Three-year old palate bone, showing a separate mass (?) over orbital process 0.

Reference

Fawcett E. On the development, ossification, and growth of the palate bone of man. (1906) J Anat Physiol., 40(4);400-6. PMID 17232695 | PMC1287457


Cite this page: Hill, M.A. (2019, September 24) Embryology Paper - On the Development, Ossification, and Growth of the Palate Bone of Man. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Paper_-_On_the_Development,_Ossification,_and_Growth_of_the_Palate_Bone_of_Man

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