Paper - The development of the hypophysis cerebri in man
Embryology - 20 Apr 2024    Expand to Translate
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Atwell WJ. The development of the hypophysis cerebri in man, with special reference to the pars tuberalis. (1926) Amer. J Anat. 37: 139-193.
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The Development Of The Hypophysis Cerebri In Man, With Special Reference To The Pars Tuberalis
Wayne J. Atwell
Department of Anatomy, University of Buffalo
Twenty-Six Figures
Aided by grant no. 210 from the Bache Fund of the National Academy of Sciences.
Our knowledge of the development of the hypophysis cerebri has been based largely upon studies on the lower mammals and other vertebrate classes. There have been comparatively few attempts to study its morphogenesis in man. Rudel (’18) remarks on the brevity of the treatment allotted this important gland in the Keibel and Mall “Embryology.”
Recently a distinct third lobe of epithelial origin has been recognized and described by a number of writers. This lobe—the pars tuberalis of Tilney—is distinguished by a number of features (Atwell, ’18b) among which may be mentioned its paired origin, its characteristic position in relation to the diaphragma sellae, and its distinct histological structure.
Although the pars tuberalis has been clearly differentiated and its development traced in a number of lower forms, it has not been generally recognized as a distinct component of the human hypophysis. This has been due in part to the small size of the lobe in the fully developed gland, but perhaps more largely to the almost entire lack of careful and comprehensive morphogenetic studies for the hypophysis of man. The former confusion of the pars tuberalis with the pars intermedia (compare Lothringer’s (/86) term ‘Fortsatz dos lflpitlielsaums’ and Herring’s (’08 a) ‘tongue—like process of the pars intermedia’ to designate what we now know as the pars tuberalis) has 11ot been entirely cleared away. This is evidenced by the following quotation from a recent work (Cowdry, ’22, p. 709): “Tl1e posterior, or intermediate portion begins to extend upward alo11g the infundibular stalk and probably gives rise to the tissue which has been recently called the pars tuberalis.” Elsewhere, however (p. 707), this writer seems to relate the pars tuberalis to the anterior lobe: “The pars tuberalis, which is so distinct in lower forms, is only represented in man by an inconspicuous prolongation of the tissue of the anterior lobe along the infundibulum.”
This study was undertaken with the object of tracing rather completely the morphogenesis of all the lobes of the hypophysis in man, but with attention directed particularly to the little known pars tuberalis. A beginning was made while the writer was at the University of hlichigan, but the study has been largely carried out and brought to completion at the University of Buffalo. It has been delayed by the great amount of time required for the collection and preparation of the human embryos contained in the embryological collection of the latter institution.
My sincere thanks are due to Prof. G. Carl Huber for the loan of six embryos from his collection and for his continued interest in this study.
Historical - Pars Tuberalis
No attempt will be made here to abstract the voluminous literature on the general features of the development of the hypophysis. The more directly pertinent contributions have been referred to in a previous paper (Atwell, ’18 a). Rather complete bibliographies are to be found in Stendell’s monograph (’14) and in “Endocrinology and Metabolism” (’22, vol. 5).
It may be appropriate, however, to bring together the more important references to that lobe of the hypophysis which we now designate the pars tuberalis. That the lobe was seen by the earlier embryologists now seems certain, but its recognition as a distinct part of the gland embryologically and histologically has come but recently.
W. Miiller (’71), Mihalkovics (’75), and Kraushaar (’85) noted a ‘tongue-like’ extension of the hypophysis and called it merely the ‘anterior process’ of the hypophysis.
Lothinger (’86) observed a small process spread out under the tuber cinereum which he named the ‘Fortsatz des Epithelsaums auf den Trichter.’ The terms ‘vorderer Lappen’ and ‘vorderer Fortsatz’ have been employed by Haller at various times (’97, ’09, ’10) to designate a thin part of the hypopl1ysis which extends forward and is closely applied to the brain wall.
Salzer (’98) figured and described a solid anterior process which consists of glandular substance and which extends toward the optic chiasm.
Joris (’07) saw in the meninges of the brain a mass of glandular cells attached to the anterior end of the hypophysis, and extending from the base of the infundibulum to the optic chiasm. The cell mass divides into two branches. These diverge and make an angle, open posteriorly, to embrace the neck of the infundibulum. To this cell mass Joris gave the name of ‘lobule de la tige.’
Staderini (’08) speaks of a ‘lobus chiasmaticus’ which extends forward and a ‘lobus praemammillaris,’ the cells of which are within the brain coverings and which surround the infundibular neck.
Herring ( ’08 a) describes a portion of the hypophysis which extends forward and is closely applied to the brain wall. This part he terms the ‘tongue—like process of the pars intermedia,’ although he recognizes that it is distinctly more Vascular than the pars intermedia proper. Blair Bell (’19) proposes a slightly different terminology to designate this lobe. He illustrates (p. 68) ‘the reticulated portion of the pars intermedia’ of the cat in contrast to the more compact portion of the pars intermedia which ‘abuts on the cleft.’
Cite this page: Hill, M.A. (2024, April 20) Embryology Paper - The development of the hypophysis cerebri in man. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Paper_-_The_development_of_the_hypophysis_cerebri_in_man
- © Dr Mark Hill 2024, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G
