Paper - Contribution to the structure and development of the vertebrate head 3
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Locy WA.Contribution to the structure and development of the vertebrate head. (1895) J. Morphol. 11(3): 497-595.
- Locy 1895 Contents: General Introduction | Part I - Metamerism of the Head | Part II - The Sense-Organs | Figures
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Explanation of Figures
1, 2, 3, 4, etc. Metameric segment.
XII« line drawn in front of the ante- Max. metameric Segment. rior neuromere of the vagus d km. nasal epitheliutth net-vie. OF. ». Optik: net-se.
tm. auditory vesicla ex. .k. optic stalk acn ». accessory Optik: Ists-Ziele. pp. z« « optic vesicle.
«. s. anterior portion of alimentary
F. paraphysis canal. 4 w. serial Sense-Organ.
cåä cerebe11um. III. tha1amencepha1on. Mk. prosencephaloxx « Mel. ex. thalamus opticus. Hei. epiphysis · New. 4 fourth ventric1e. II. c. manclibulax head cavitzk Zp. Zirbe1po1ster.
Explanation of Plate XXVL
The figures are from untouched negatives and are noteworthy in showing the very early condition of the optic vesicle, the accessory vesicles and in some cases the primitive rnetameric segrnenta They are all photographs of Squalus acanthias and, with the exception of Fig. 7, are X about 20 diameters.
Fig. 1. Photograph of embryo between Balfour’s stages B and C.
FIg. 2. Somewhat older embryo. The embryonic rim on the left side shows faintly Some of the metameric segments (not reproduced by the artist).
Fig. 3. Slightly older embryo to show the forrnation of the heachplate and the Central wedgeshaped Process thereon. This is the stage in which the neural folds are started along the margins of the body. They are ventrally curved.
Fig. 4. Stage with a rounded head-plate when the optic vesicles first become evident.
Fig. 5. Another embryo, about the same age as the Preceding, in which the optic vesicles and one of the accessory vesicles are shown.
Fig. 6. Somewhat older embryo showing the infolding for the optic vesicles extending across the median Plane.
Fig. 7. Older embryo somewhat higher magnifred The headsplate is very broad, the trunlc narrow. The neural folds of the head lie nearly in the horizontal Plane. The rnetarneric segments show well on the left margin of the head-P1ate. They exist in the earlier stages, but are very diiiicult to catch with the camera.
Fig. 8. speeirnen in which the dePressions for the optic vesicles show very distinctly
Figs. 9 and 10. Two ernbryos older (although smaller) than the preceding. In both two Pairs of accessory optic vesicles are to be seen on the cephalic Plate baclc of the Primary optic vesicles.
Figs. 11 and 12. Two specimens slightly older than the preceding two, seen from different Point of observation
Fig. 13. Embryo after the neural folds have begun to grow uPwards, seen obliquely from the left sicle. Gives an external view of— the vesicles on one side and an internal view of them on the oPPosite side of the neural folda
Fig. 14. Embryo from which Fig. 29, Plate XXV1I, is drawjx Shows metaIneric segments on the exPosed ventral surface of the neural folds.
FIg. 15. Embryo of same age as Fig. 13 and Fig. Hi, Plate XXVII. shows metarneric segments on the neural folds in front of the eye vesiclea
Fig. 16. Embryo of the same age as Fig. 9 just above it. Seen in a Position more favorable to bring out the accessory vesicles on the cephalic plate. The optic vesicle on the right side shows as an external Protuberance.
Fig. 17. somewhat older embryo viewed obliquely from above. shows the optic vesicle of the right side as an external rounded Protuberance, and that of the left side from within as a cup. Behind the optic vesiele on the left side of the cephalic place are four accessory vesiclea They show their serial reiation with the Primary optic vesicle.
FIg. 18. specimen showing a large development of the central tongueislilte Process. Embryo slightly older than that in Fig. 7. 586 Lock.
Figs. 19 and 20. Side view of two heads of embryos vvith open neural groove to show the external appearance of the optic vesicle
Fig. 21. Embryo of same age as Fig. 13 viewed obliquely from above.
Fig. 22. Side view of embryo of the same age (with broadly open neural gross-re) to show the external appearance of the optic vesicie and the other vesicles behind it.
Fig. 23. Embryo after partie-l closure of the neural groove Showing two openings, an anterior and a posterior one, into the neural canaL
Fig. 24. Some-what older specimen with head broken off. showing three openings (sma1ler than those in the preceding embryo) into the neural canaL
Explanation of Plate XXVII
All the figures are of Squalus acanthia they are drawn with the aid of thecamera, and are all d( 45 diameters.
FIG. 25. Young embryo intermediate between Balfoufs stages B and C. The embryo so far as formed is divided into eight pairs of metameres and these arecontinued without brealc, or any change in Character, into the halves of the embryonic rim. The eleventh Inetamere which, in later stages, lies in kront of the vagus nerve is now on either side the third one from the axial embryo.
Fig. 26. Somewhat older embryo, showing the change in form of the head region. The axial embryo now includes about fifteen pairs of rnetamerea
Fig. 27. Slightly older than the precedingz there are about eighteen pairs of rnetameres in the axial part of the embryo and,·as in the forrner instances, are continued into the embryonic rim. Two longitudinal marginal furrows have appeared, separating two marginal bands from the rest of the embryo. Along the line of these furrows are seen four depressions that mark the very beginning of segmental Sense-Organs.
FIG. 28. View from the upper side of the same embryo illustrated in Fig. 29. The cephalic plate is now clearly marked off from the more slender trunk region. The depressions for the optic vesicles (c-P.) have made their appearancqz
F1G. 29. View of the same embryo from the ventral aspect. The yolk has been cornpletely removed, and we get a view directly into the gastrular cavity. There are eleven pairs of metameres in the broad part of the cephalic plate. The neural folds are ventrally curved The outlines of the figure and the neural segments are too syrnrnetricaL
FIG. 30. Older embryo with neural folds lying in the horizontal plane. The broad cephalic plate is in marked contrast with the slender trank.
Fig. 31. Embryo in which the neural folds have nearly attained the vertical Plane. The neural groove is still open. The optic vesicle (qk).) and the combined vesicle of mid—brain and accessory optic Eis-z. -l- A. tax-L) vesicle show on the sides of the head. There is also the beginning of rnandibnlar head cavity El. c) and the branchia1 pouch. The original Inetameric divisions are still very plain.
FIG. 32. Embryo just after the closure of the neural groove in the anterior end. The posterior part of the neural canal is not cornpletely closed. Note the metarneric divisions indicated by numbers J, e, F, etc. ·
Fig. 33. Embryo after complete closure of the neural groove and before the appearance of the ear vesicle.
Fig. 34. Embryo after the differentiation of the ear saucen The five anterior metarneric divisions are no longer distinguishable, those of the hind-brain are prominent and are approximatecl in the middle plane. 0ne gilbcleft has broken through. The nasal pit has started. ·
Fig. 35. slightly older embryo showing several characteristic changea The— line of neural segments are being forced apart by lateralgrowth of the roof of the hind-brain. The fifth nerve is plainly visib1e. Over the gillsclefts runs a continuous nodulated thiclcening containing the branchial Sense-Organs and the radirnent of the lateral 1ine. 588 Lock:
Fig. 36. Some-what older embryo differing from the preceding mainly in show ing the rudiments of the seventh, eighth ninth, and tenth next-es. Note the lens and choroid Hssure in the eye vesic1e.
Fig. 37. Slightly older than the precedjng The line of neural segments are undergoing some ehanges whereby the concavity on the lower margin is made to correspond vvith a crest on the upper margitx In embryos of about the age represented in Fig. 36 or a very little older the epiphysial outgrowth arises from the roof of the tha1amencepha1on.
Explanation of Plate XXVIIL
A series of partial dissections of embryos of syst-III« in such a way that the brainswalls have been laid bare. .Figs. 46—49 X 45 diameters Figs. »so-so X io diameters.
Fig. 38. Embryo with open neural groove. The epidermal layer and the mesoderm have been removed from the sides of the brain-Wall; behind the optic vesicle is seen a bilobed protuberance—t·he combined mid-brain vesicle and the anterior accessory optic vesicle.
Fig. 39. 0lder embryo with neural canal partly formed. The specimen shovvs the same condition of mid-brain vesicle and that of the anterior accessory optic vesicle »
Fig. 40. The braiwwalls of an embryo of the same age as that shown in Fig. Ja.
Fig. 41. Embryo before dissectiom showing especially well the contours of the brain-wal1s.
Fig. 42. The same embryo after exposure of the braiwwalls by dissection The thalamencephalon is well exhibited · The mid-brain is bilobed.
Fig. 43. slcetch of partially dissected embryo just after the appearance of the auditory vesicle.
Fig. 44. The exposed brainwvalls of an embryo slightly older than that represented in Fig. 34. ..
Fig. 45. Brain of embryo about same age as that in Fig. 35. The auditory vesicle has been Ieft in Position. The midbrain is now indistinctly trilobed.
Fig. 46. Brainwvalls of embryo with the optic vesicle removed. About the same age as the preceding
Fig. 47. Dissection of the brain of the embryo of which Fig. 36 is an external view. The mid—brain is distinctly tri1obed. There are eight clearly marked segments in the hind-brain.
Fig. 48. Dissection of embryo slightly older than the one represented in Fig. 37. The thalamencephalon is now dekinitely marked out by furrows ; it bears upon its summit two rounded confluent pr0tuberances.
Fig. 49. Dissection of brain of embryo somewhat older than the preceding The thalamencephalon is clearly defined. The posterior protuberance from its roof has grown much faster than the anterior one. The former is the beginning of epiphysis. There are nine neural segments in the hind-brain.
The embryos are now too large to represent advantageously on the same scale, and in the following figures the scale of magniiication is reduced from 45 to 10 diameters.
Fig. 50. Shows embryo of same age as that represented in Fig. Ja.
Fig. 51. Embryo of nearly the same age as that represented in Fig. 34.
Fig. 52. Partly dissected embryo of about the same age as that represented in Fig. 36 and again in Fig. 47.
Fig. 53. Braiiikwalls of an embryo just older than that shown in Fig. 49.
Flgs. 54 and 55. Successively older embryos to show especially the changes in the tha1amencephalon and the outgrowth from its roof of the epiphysis.
Fig. 56. The same brain shown in Fig. IF, with the cerebral lobes removed and turned so as to vievv directly against the epiphysis.
Explanation of Plate XXDL
Figs 57—62 a continuation of the series of dissections shown on the two previous plates. All X io diametera Figs. 65—87 X 45 characters.
Fig. 57. Side view of brain of an older embryo than that slcetched in the fore— going ügure The neural segments have now become ob1iterated, and the three lobes of the mid—brain (secondary«divisions) are no Ionger distinguishable The epiphysis is well developed ; in front of it is a semicircular fold of the braiwwallz this structure is the remnant of the elevation which started in front of the epiphs ysis on the roof of the thalamencephalon (see Figs. 48 and 49). It has become rednced by compression between the rapidly growing adjacent brain regions. The paraphysis is also visible in this drawing
Fig. 58. View of the same brain from above looking into the cavity of the fonrth ventriclia
Fig. 59. The same brain after removal of the cerebra1 lobes and arranged so as to show the epiphysis in front view.
Fig. 60. Brain of older embryo showing substantially the same features as the preceding
Fig. 61. The cerebral lobes of the same brain after removal. Note the paraphysis arising from the posterior part of the roof of the prosencephaloiic
Fig. 62. The same brain after removal of prosencephalon and arranged so as to show to best advantage the epiphysis with its Stall-r.
Fig. 63. Horizontal Section of ernbryo shown in Fig. 25 to show the general appearance of the metameres in Section. X so.
Fig. 64. Horizontal Section of embryo sketched in Fig. 26 showing metameres in Section, and adjacent layer of mesodernn X Ho.
Fig. 65. Section of heacl of Tasse-ob ocelzaro through the optic vesicles at the time of their first appearance compare this with Zieglers’ Pl. IV, Fig. i93.
Figs. 66, 67, 68, 69, 70. successive sagittal Sections of embryo just after closure of the neural groove and prior to the appearance of the ear vesicle show the primary for-obtain, the inid— and hind—brains, and three very prominent neural segments of the hindsbrain The segments are the seventh, eighth, and ninth respectivelyn When the ear is first differentiated it arises opposite the ninth Segment.
Fig. 71. Deeper section of the same embryo showing a curved line of mesoderm over the mandibular cavity.
Fig. Je. Sagittal Section of ernbryo near the median plane after the formation of the auditory saucer and the complete closure of the neural groove. The five neural segments of the fore- and mickbrain are exhibited The second neural Segment nearly coincides in Position with the neuropore
Figs. 73, 74, 75. Three successive sagittal Sections of an embryo of about the age of that drawn in Fig. 34. It is slightly older, shows well the neuromeres of the hind-brain. The ear capsule is in the space of the tenth neuromere. In front of it in Figs. 73 and· 74 are seen the roots of the seventh and. eighth nett-es.
Figs. 76-87. Sagittal Sections of the specimen photographed as Fig. 17, Pl. XXVL Giving evidence of a series of cupälike depressions on the neural plate of headand trank. The series of these cupped areas is terrninated in front by the optic vesicles 0n the cephalic plate they are relativelzss large and resemble the primary optic vesicles in mode of origin and in structure How far the series extends into the trank I have not been able to determine.
Explanation of Plate XXX
Fig. 88—1 la. Twentystive transverse Sections of an embryo very slightly older than that represented in Fig. I6. The Sections 88-1oo 1ie in the region of the cephalic p1ate. The following Sections los-I 12 lie in the neck and trunlc regions
These Sections are remarlcable in bringing to Iight serial depressions along the walls of the neural folds. They show that the serial cup—like differentiations extend back of the cephalic plate. I have not been able to determine the number of serial differentiations of this Character in the embryo, but it is clear there are several pairs behind the cephalic plate upon which I have noted in surface study four pairs in addition to the eyes. X 45 diameters.
Figs. II 3——1 I s were drawn from nature by Miss Tanetta Gilleland Figs. 117 and 118 are talcen from Kupffer’s «Studien zur vergleichenden Entwickelungsgeschichte des Kopfes der KraniotenX and Fig. 116 is after FroriepJ
Fig. 113. View of the head-end of embryo of xlmzhxxoma in the open neural groove stage, X about Io diameters. shows segmental folds in the neural folds and a sMooth neural plate.
Fig. 114. View on the caudal extremity of the sarne embryo.
Fig. 115. Embryo of Kam: Pelz-sinks- showing large obvious segmental folds in the median plate and also srnaller fainter folds in the neural ridges. The latter correspond to the segments in the neural ridges in -4-zäJ·J-.kzo»-a.
Fig. 116. Embryo of THE» cyisiazms after Froriep. showing large obvious folds in the median plate with unsegmented neural ridges These median folds probably correspond to those in Reiz« Feier-Iris and nof to the Inetameric divisions in the neural folds.
Fig. I17. View on the head-end of Falæwamlsa »Im, according to Kupffen showing segmental folds in the median plate but none in the neural ridges com pare vvith Fig. II s.
Fig. I18. Caudal end of same embryo.
Figs I19-124 are sagittal Sections of syst-il arg-Esset. X about 45 diameters.
Fig. 119. Section of head of embryo about same age as those represented in Figs 37 and 48, showing the roof of the thalamencephalon raised into two elevations.
Fig. 120. somewhat older embryo showing the tubular like growth of the .epiphysis.
Fig. I21. still older stage showing reduction of the anterior part of roof of thalamencephalon and great increase in depth of the furrow in front of the thalamencephalotn
Fig. 122. 0lder stage in which the paraphysis has made its appearance from sthe roof of the prosencephalotn The choroid plexus has also started.
Figs. 123 and 124. Two older stages showing the increase in length of the epiphysis ; its distal end is somewhat enlarged and is inserted into a concavity in the cranial roof. The paraphysis is indicated at pp. — The choroid plexus is considerably increased in extent and hangs into the cavity of the fore-brain.
- Locy 1895 Contents: General Introduction | Part I - Metamerism of the Head | Part II - The Sense-Organs | Figures
Cite this page: Hill, M.A. (2021, April 13) Embryology Paper - Contribution to the structure and development of the vertebrate head 3. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Paper_-_Contribution_to_the_structure_and_development_of_the_vertebrate_head_3
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