Paper - Persistence of the organ of Chievitz in the human
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Ramsay AJ. Persistence of the organ of Chievitz in the human. (1935) Anat. Rec 63(3): 281-290.
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Persistence of the Organ of Chievitz in the Human
Andrew Jackson Ramsay
Department of Histology and Embryology, Cornell University, Ithaca
Two Plates (14 figures)
The buccal sulcus in the human embryo gives rise very early to two constant structures, the ‘organ of Chievitz’ and the anlage of the parotid. The former is the first to appear (8 to 11 mm) and rapidly becomes separated and displaced from the sulcus. Thus it has escaped the notice of many investigators and also in many cases it has undoubtedly been mistaken for and described as the parotid anlage. Due to the absence in current embryology texts of any comment concerning this curious structure it was thought advisable to present here a brief statement of the literature, as Well as a very short account of the development and persistence of the organ in the human.
Chievitz (1885) was the first to describe a strand of epithelium parallel with the lateral border of the sulcus buccalis, medial to the masseter, mandible, and internal pterygoid muscle, and having no connection With the oral epithelium or the parotid duct (10-week fetus). This structure later came to be known as the ‘organ of Chievitz’ and this term or name is here retained Without any implication of a functional value which the term ‘organ’ suggests. In a 12-week fetus Chievitz mentioned the presence of a similarly placed ‘duct’ but which differed from that in the 10-Week fetus in that its oral extremity was eonnected to the parotid duct just as the latter passes the antero—lateral border of the mandible. His (1885) described the sulcus buccalis in a young human embryo and evidently mistook the organ of Chievitz for the parotid bud.
Hammar ( ’01) also described the sulcus buccalis iii an early embryo (18.5 mm.) but failed to recognize the two components. Bujard (’11) reported, in an embryo of 35 mm., a cord of epithelial cells ental to the masseter and mandible and having no connection with the oral epithelium or the parotid duct. He recognized this structure as the orga.n of Chievitz. Weishaupt (’11) noted the presence of the organ in twentyfour human embryos ranging in size from 30 to 310 mm. It could not be found in one embryo of 13.5 mm., two of 18 mm., and one of 25 mm. An embryo 35 mm. in length possessed the organ only on the left side. lVeishaupt interpreted this epithelial cord as a rudimentary side branch of the parotid duct and termed it (as did Robert Meyer) ‘ramus mandibularis ductus parotidei.’ Schulte (’13 a), using a limited series of human embryos, has given an excellent account of the early developmental history of the organ. Schulte gave the organ a new term, ‘orbital inclusion,’ since it arises from the buccal sulcus where the orbital glands may arise and then becomes embedded or included in the mesenchyme bordering the oral epithelium. The oldest material Schulte presented was a redescription of Chievitz’ 12-week embryo. In the oldest embryo which Strandberg (’18) studied (114 mm.) the organ was interrupted in its midportion. It possessed no lumen, and showed indications of a tendency to form sprouts. Braehet (’19) termed the structure ‘traetus bueco— pharyngien.’ Bollea ( ’24) described the organ of Chievitz in young embryos but failed to find it in an embryo 130 mm. in length, concluding that it had disappeared by that time.
Fifty—four human embryos (7.5 to 95 mm in length) of the Cornell collection were used in this study. In addition, the region containing Chievitz’ organ was removed from fetuses 135 mm., 195 mm., 235 mm. in length, and also from four mature fetuses. This material was stained en tote with Mayer*’s H01 carmine a.nd was sectioned serially.
Observations and Discussion
The organ of Chievitz appears in embryos 7.5 to 9.5 mm. in length (fig. 1) as a. slight thickening of the epithelium forming the fundus of the caudal one-third of the sulcus buccalis. The dorsal and Ventral walls of the sulcus become pressed together by the expanding mandibular and maxillary processes so that in embryos of 8.5 to 13 mm. (figs. 2 and 3) a definite oral-aborally directed fold of epithelium is formed. The buccal nerve crosses the fold of epithelium near its middle, a relation which it permanently retains. Further constriction and the subsequent ingrowth of mesenchyme begin to separate the epithelial fold from the pharynx (fig. 2). The separation starts at first caudally and proceeds toward the oral end of the fold until, in embryos 13 to 17 mm. in length, it has been completely separated from the buccal epithelium. As development proceeds the masseterie and internal pterygoid muscle masses appear on either side of the developing mandible. At this time the relations of the organ of Chievitz may be stated as follows: the caudal extremity of the organ rests against the medio—oral border of the internal pterygoid muscle (fig. 4), extending orally parallel with but completely separated from the buccal sulcus. It crosses the buccal nerve medially (fig. 5) and curving laterally ends blindly near the oral border of the masseter (fig. 6).
With the subsequent expansion of the mandible and its muscle masses, particularly in the caudo-oral direction, the epithelial strand is drawn out. Its oral end tends to be displaced laterally across the oral border of the ramus of the mandible and the masseter muscle to end quite near the parotid duet (figs. 6 and 7). Both the oral and caudal ends of the organ tend to become expanded and possess lumina. figure 7 illustrates the condition which has led some investigators to conclude that the organ of Chievitz is at side branch of the parotid duct. If, however, younger stages had been studied the widely separated origins of the organ and the parotid would have been seen and it would have been apparent that the proximity of the two was effected secondarily. Due to its mechanical elongation the organ becomes thin many times in its midportion. When this occurs it is usually the part immediately ahead of the buccal nerve which in tenuous. In over half the embryos 25 to 55 mm. in length the oral end of the organ becomes separated off and lies free in the mesenchyme near the parotid duct (figs. 7 and 8). figure 9 illustrates the plan of the position and relationships of Chievitz’ organ in the 135-mm. embryo.
Mesenchyme becomes organized around the organ in 65-min. embryos and later becomes a quite dense connective tissue. In the newborn fetuses studied this dense tissue contained numerous cells of the granulopoietic series. The mesenchyme immediately adjacent to the epithelial strand usually remains loose and is fairly vascular in the later stages. The organ shows a_ tendency for further growth in the appearance of small sprouts and buds (figs. 9, 10, 11, 12, 1.3 and 14) starting in embryos 90 mm. in length. These young sprouts are composed of darkly staining ‘basal cells,’ i.e., cells similar in appearance to those which comprise the basal layer (stratum cylindricum) of stratified squamous epithelium (figs. 11 and 12).
In newborn fetuses a variable appearance in Chievitz’ organ is encountered. Some of the sprouts have become ‘epithelial pearls’ (figs. 11, 12, 13 and 14) which are quite similar to those occasionally found in the epithelial palatine raphe. The sprouts in some fetuses are composed of an expanded central portion containing large clear cells, comparable to the surface cells of the oral epithelium, and an outer rim of ‘basal cells’ (figs. 13 and 14).
Some investigators have interpreted these sprouts and buds as abortive gland tubules and alveoli and consequently have given the organ of Chievitz a salivary gland potency. The fairly abundant material used in this study does not allow such an interpretation. A study of the sprouts in mature fetuses shows that they have various shapes and forms, some are elongated, some short and thick, while others are merely ﬂanges or folds emanating from the main epithelial strand.
Nothing was found in the morphology or the histological structure which would justify a comparison of the structure with true glands.
In every embryo used in this study the organ of Chievitz was present 0n both sides and, in the younger stages, very little variation in size and relations was found. No evidence of a connection between the organ and the parotid duct could be found.
The question of the interpretation of the organ of Chievitz may be brieﬂy commented upon. As stated in the paragraph above some investigators (Weishaupt, and others) believe that the organ represents an abortive salivary anlage, probably of the molar, buccal, or orbital series, and that it results from a reduction of the salivary gland mass during phylogenesis. If this hypothesis is correct it would be expected that animals possessing; an enormous salivary apparatus (eX., ruminants) would not have Chievitz’ organ. I have studied the entire Cornell collection of calf and sheep embryos and, in every case, have seen the organ. The idea that tl1e organ represents an endocrine gland hardly deserves mention. Broman (’l6 a and b), from his observations on two species of antarctic seals, suggested that the organ represents the position of the parotid gland earlier in phylogenesis, when (according to his theory) the parotid was situated farther caudally a11d was of a mucous type to aid in swallowing. Later, with the subsequent change in diet the parotid gland changed its secretion to a serous one and developed from a previously small gland located more orally. The primary parotid was thus reduced to a column of epithelial cells, the organ of Chievitz. The most plausible suggestion is that of Bollea (’24) Who explains the organ as a. residual epithelial lamina resulting from the fusion and growth of the mandibular and maxillary processes. He parallels Chievitz’ organ with the epithelial raphe of the palate. Mantero (’27) dislikes Bollea.’s interpretative comparison but recognized a similarity which is useful as a working hypothesis.
From the results of various investigators on a great number of animals (cat, dog, pig, horse, mule, sheep, calf, mole, treeshrew, squirrel, rabbit, chevrotain, opossum, guinea pig, mouse, rat, monkey, deer, two species of antarctic seals, and perhaps other animals) its appears that the almost universal presence of Chievitz’s organ indicates some fundamental developmental process common to all. Such a process is presented by the growth and fusion of the mandibular and maxillary processes with an accompanying constriction and ﬂattening of the sulcus buccalis. The presence of the fifth cranial nerve immediately lateral to the sulcus possibly helps in inhibiting lateral expansion in that region of the mouth in young embryos. As the nerve is later mechanically displaced from the sulcus it may also aid the ingrowing mesenchyme in separating the organ from the remainder of the sulcus. I have found no indication of the structure becoming a gland, either endocrine or exocrine in character. From observations on the mature human fetuses one feels correct in concluding that Chievitz’ organ represents non-adaptive oral surface epithelium deprived of its surface relations and that its sprouts and buds indicate merely a tendency for further growth.
In pointing out a degree of parallelism between the organ of Chievitz and certain of the ‘ pharyngeal derivatives’ one is perhaps stepping outside the bounds of conventionalism. The organ of Chievitz, arising as it does between two expanding and fusing mesodermal masses (mandibular and maxillary processes), bears a developmental parallelism with the pharyngeal derivatives of entodermal pouch origin, and also with the cervical. vesicle, Whose various fates in the different animals reﬂect qualitative and quantitative differences in the fundamental environmental relations characterizing the early developmental period. The cervical vesicle, for example, is an ectodermal inclusion determined by the growth shiftings characteristic of the pharyngeal region and its fate may be threefold: 1) it may degenerate (in most animals), 2) it may persist as a cervical cyst, and 3) it may in part, in some animals (pig and guinea pig), become thymus. It may be that the ultimate fate of such an epithelial structure which becomes embedded in the surrounding tissue (mesenchyme) rests upon the early vascular and mechanical relations into which it is introduced. If favorable conditions are met in the developmental epoch of such an ‘inclusion’ its fate might be quite different from that of a non—adaptive and passive existence. It is well to here emphasize the fact that the mere presence of a structure, such as the one under consideration, does not mean that it possesses some definite function or that it has a particular significance as an organ.
In pathological literature I have found no reference to tumors or cysts which could be interpreted as arising from Chievitz’ organ, although, very probably, study of material older than that from mature fetuses would reveal the presence of small cysts, since in one newborn fetus small cavities were evident. No function can be allotted to the organ. It presumably degenerates as development proceeds or remains as a variable passive epithelial remnant.
While no attempt has been made to include a thorough review and discussion of all the literature on this subject, particularly concerning animals other than man, a fairly complete bibliography is offered.
BOLLEA, M. 1924 Sull’o1-gano di Cliieviti del1’uomo e di aleuni mammiferi. Arch. ital. anat. e. di embriol., vol. 21, pp. 464-486.
BRACTIET, A. 1919 Sur le tractus bucco~pha1'yngien; Orgcne de Chievitz ‘Orbital inclusion’ (1.). C. R. Soc. (16 Bio1., vol. 71, pp. 923-925.
BROMAN, I. 1916a Die Parotis der Chi:-optera——eine Oberlippendriise. Anat. A112,, Bd. 49, S. 65-71.
- 1916b Ueber Chiovitz Organ (‘Ramus mandibularis ductus parotidei’ oder ‘Orbital inclusion’) und dessen Bedeutung nehst Bemerkungen fiber die Phyloge-‘nese der Glandula parotis. E1-gebn. d. Anat. u. Entw., Bd. 22, s. 602-622.
BUJARD, E. 1911 Reconstruction plastique dos glandes salivaires d’un foetus humaine de 10 semaines environ. Anat. .Anz., Bd. 38, S. 115-127.
CASAROTTO, G. ‘1928 Sulla morfogenesi dell ’o1'gano di Chievitz. Stomatologia, vol. 26, pp. 871-886.
CHIEVITZ, J. H. 1885 Beitrag ziir Entwickelungsgeschichte der Speicheldriiscu. Arch. f. Anat. u. Physiol. Anat. Abt. S. 401-436.
GOEDBLOED, J. 1927 Ueber die relative Verkiirzung dcr Mundspalte in bezug auf die Innenbekleidung der Wangen, inshesondere bei de-m Schaf und dem Kaninc-hen. Zeit. f. Anat. u. EntW., Bd. 84, S. 656—668.
HAMMAR, J. A. 1901 Notiz fiber der Entwicklnng des Zunge und der Mundspiechcldriisen beim Menschen. Anat. Anz., Bd. 19, S. 570-575.
HIS, W. 1885 Anatomic menscl1enliol1cn Embryonen. Th. III. Leipzig.
MANTERO, S. 1924 Lo sviluppo della ghiandola parotide e del1’0rgan0 del Chievitz. Ricerchc di Morfologia, vol. IV, pp. 129-188.
1927 Ulteriori considerazioni sn1l’organo di Chievitz. Monitors zoologico italiano, vol. 38—39, pp. 206-212.
MORAL, 1-1. 1913 Ueber die ersten Entwioklungsstadien der Glandula parotis. Anat. Hefte, Bd. 47, S. 385~491.
1919 Zur Kenntnis V011 (ler Spheieheldriisenontwicklung der Mans. Anat. Hefte, Bd. 57, S. 49-208.
PAULET, J. L. 1911 Kopf nnd bucconasale Bildungen eines Inenschlichen Embryo Von 14.5-mm. Scheitelsteisslfinge. Studien und plastische Reeonstruktionen. Arch. f. Mikr. Anat. u. Entw'1ckel., Bd. 76, S. 658-681.
SCHULTE, H. VON W. 1913a The development of the salivary glands in man. Contributions to the Anatomy and Development of the Salivary Glands in the Ma.mma.lia. Studies in Cancer and Allied Subjects, vol. IV, pp. 25-72. Columbia University Press, New York.
1913 b The development of the salivary glands in the domestic cat. Contributions to the Anatomy and Development of the Salivary Glands in the Mammalia. Studies in Cancer and Allied Subjects, vol. IV, pp. 191-313. Columbia University Press, New York.
SCHUMACHER, S. 1924 Der Ban der Wangen (insbesondere (loreu Innenbekleidung), verglichen mit dem (lcr Lippen. Zeit. f. Anat. 11. Entwickel., Bd. 73, S. 247—276.
1927 Die Mundluiihlc. V011 M6lle11(1o1*iY’s Handbuch der Mikr. Anat. des Mensehcn, Bd. V, S. 1—60. Berlin.
STRANDBERG, A. 1918 Beitrag zur Kenntnis des Chievitz’schen Organs. Anat. Anz., Bd. 51, S. 177-195.
Wn1sIIAUP'r, E. 1911 Ein Rudimentiirer Seitengang des Ductus parotideus (R-amus mandibularis ductus parotitlei). Beitrag zur verglcichenden Entwicklungsgesehiclite der Mundspei(3.heldr1'isen. Arch. 1’. Anat. u. Pl1ysi0l., Anat. Abt., S. 11-3 .
1 Parasagittal section of a 9- to 10-mm human embryo. The lateral portion of the suleus buccalis is composed of darkly staining cells. This is the anlage of the organ of Chievitz (indicated by the arrow). X 22.
2 Parasagittal section of a 11.5-mm human embryo. Marked growth of the maxillary and mandibular processes and their accompanying fusion lateral to the suleus buccalis is evident. The organ of Chievitz (indicated by arrow) is being separated from the remainder of the sulc-.11s. X 22.
3 Transaction of the left side of the mouth in a 13-mm human embryo. The tongue is at the right. The mesodermal condensation indicates rapid growth of the material dorsal, lateral, and ventral to the suleus l>u(-,c:alis. fibers of the fifth cranial nerve are seen at the extreme left and at the lower left. The organ of Chievitz (cephalic end) has not been separated from the bueca] epitlielium at this level. X 55.
4: Transeetion of the left side of the mouth of at human embryo 32 mm in length. The mandible and Met-kel’s cartilage are seen at the left and lower center. The arrow points to the caudal end of the organ of Chievitz which rests against the medial side of the internal pterygoid muscle. X 22.
5 Same. This section is taken -1-50p. rostral to that shown in figure 4. The arrow shows the midportion of the organ as it passes medial to the bueeal nerve. x 22.
6 Same. This section is taken 225;» rostral to that shown in figure 5. The rostral end of Chievitz’ organ is eurving laterally across the oral border of the ramus of the niandible to end quite near the parotid duct (1'’.). X 22.
7 Parasagittal section of the head of a 20-min. human embryo. Preser\'atio11 is poor. An arrow indicates the expanded oral end of Chievitz’ organ (Which in this embryo is separated from the main extent of the organ) lying very close to the parotid duet (P.) near the point of attaeliment of the latter to the buccal epithelium. X 22.
8 Parasagittal section of the head of a huinan embryo 55 mm. in length. The oral end of the organ is lying free in the mesenchyme near the parotid duet (P.). The nmndible is seen at the left. X 22.
9 Horizontal section through the right side of the head of a 135-11111‘). human embryo. The rostral end is at the right. At the top is the l)u(',e:»ll epithelium. ‘The internal pterygoid muscle (P1,) and the masseter muscle (M.) are on either side of the space from which the inaudible has been removed (lower centei"). The arrows indicate the middle and oral nne—t'ourth of Chievitz’ organ, at the left of which is the bueeal nerve (N. 13.). X 12’.
10 Horizontal section through the left side of the head of a 95-mm human embryo. The oral end is at the top. A superior dental anlage is seen in the upper ecnle1'. The bin-ml sulcus shows in the right center, the mandible is at the lower left. A11 arrow points to Chievitz’ organ which, in this einbryo, is sliglitlj.‘ braliched. X 22.
11 Trulisection of the organ of Chievitz in a, mature human fetus. Note the rzolunmar character of the cells Wl1l('l1 make up the sprouts. Two ‘epithelial pearls’ are seen in this section. X 180.
12 Photograph of a transection of Ghievitz’ organ in 21 mature human fetus. Two areas slmwing large clear cells are present. X180.
13 Longitudinal section of the o1'_,;ran of Chievitz in a mature human fetus. Note the expanded central portion :».1.nd its cliaractei-istic stratifiecl squamous epithelial cells among which small cavities are seen. Note. also the darkly staining basal cells. X 95.
14 Longitudinal section of Chevitz’ organ in a mature human fetus. The buds and sprouts have changecl into typical stratified squamous epithelial cells. X 95.
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