Paper - The inguinal canal in the foetus and new-born (1944)
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The Inguinal Canal in the Foetus and New-born
By H. Curl Ann R. G. Tromly
From the Division of Anatomy of the University of Tennessee, College of Medicine
Most anatomists, undoubtedly, are aware that the inguinal canal is formed very early in foetal life, yet it is true that many students graduate from medical schools with the fixed belief that no canal is present at the time of migration of the testis from the abdominal cavity to the scrotum.
There may be several reasons why this belief prevails. The subject may be presented so early in the course that the student does not grasp its significance or fails to appreciate the relative size of the undescended testis and the inguinal canal, or it may be because at least one of the text-books of gross anatomy, widely used in our school, specifically denies the existence of an inguinal canal at the time the testis leaves the abdominal cavity.
Inability to find any published data on the inguinal canal at the time of testicular descent prompted this study. Encouragement to submit our findings for publication has been given by a recent paper by Wyndham (1943) on ‘A morphological study of testicular descent’. ‘
W. Felix (1910), in Keibel & Mall, gives a complete and detailed description of the abdominal musculature and the formation of the inguinal canal. He describes the formation of the ‘chorda gubernaculi’ before there is any differentiation of the abdominal muscles, and says (p. 944) that when the musculature begins to develop ‘it must grow around the chorda gubernaculi and thus there is necessarily formed a canal (the inguinal canal) whose contents were there from the beginning’. Other books on developmental Anatomy (Arey, 1940; Jordan & Kindred, 1937) give a similar, but less detailed, description of this process. _
Text-books on gross anatomy vary greatly in their presentation of this subject and in the completeness of the details given. Piersol (1930), Cunningham (1937), Grant (1940) and Gray (1942) either describe an inguinal canal or imply that one is present and state that the testis passes obliquely downward and medially through the abdominal wall. Morris (1942) denies the existence of a canal, as is shown by the following statement: ‘It is helpful to note that originally this outpocketing extends directly outward (not obliquely), so there is no canal, but one ring lies directly behind the other.’
In the current literature, Watson (1938), and Cherner (1939), in discussing the canal in relation to various types of hernia, confirm the major points previously described by Felix (1910). Howell (1989), and much more extensively Anson and associates (1988, 1941), have written in detail of the development and anatomy of the abdominal wall in relation to the surgery of the inguinal region but without specific mention of the development and the dimensions of the inguinal canal in the foetus.
The material in this study consisted of twenty-five foetal and infant cadavers, seventeen male and eight female. Clinically, twelve were classed as miscarriage or abortion, three were not classified, nine were classed as ‘stillbirth’, and one was 24 days old at time of death. The right and left inguinal region and inguinal canal were dissected in each cadaver. As there was no essential difference in the measurements on the two sides only one measurement is included in Table 1. Tabulation is arranged according to foetal length (mm. crown-rump), and not in the order of dissection. All dissections and measurements were made after the material had been ‘fixed’ or embalmed.
As the margins of the abdominal inguinal ring are difficult to define sharply, measurements were made from the adjacent inferior epigastric artery.
By careful dissection and by traction on the contents of the canal, the margins of the subcutaneous ting could always be established. The distance was then taken from the superior lateral margin of this ring to a point on the inferior epigastric artery as noted above. ‘
In the case of the female specimens the margins of the subcutaneous inguinal ring could always be defined by traction on the abdominal part of the round ligaments. Measurements were then taken as in the male specimens.
Wyndham (1948) reports the inguinal canal well developed in the foetus at 66 mm. (crown-rump) length. In no specimen of 238 cm. or less, in his series, had testicular descent begun, yet it was completed in every specimen, except one, of 24 cm. or over.
From our observations it can be definitely stated that there is an inguinal canal in all foetuses dissected in this study. In our earliest stage it is 4 mm. long; just before testicular descent it measures 9 mm.; in our older specimens after the testis has descended into the scrotum the canal varies in length from 10 to 15 mm. Similarly, in the female specimens the length of the canal varies from 4 to 16 mm.
After it had been found that a canal was present, even in the youngest foetuses dissected, it seemed of interest to measure the testis in those cases in which it had not yet passed from the abdomen. In these cases the gubernaculum completely filled the canal. It was a firm cylindrical mass and measured from 2 to 3 mm. in diameter. The testis was an elongated, slightly flattened, body from 4 to 7 mm. in length and about 3 mm. in thickness. It would seem, therefore, that this soft mass might easily follow the gubernaculum through the canal without any distortion of either.
In the earlier stages, up to 180 mm., the inguinal canal was almost parallel to the lateral border of the rectus abdominis, ‘but thereafter, with increase in width of the pelvis, it became parallel to the inguinal ligament.
- There is a definite inguinal canal in the male foetus before the testis passes through the abdominal wall.
- The testis at this time is not large enough to disturb the relationship of the inguinal rings.
- In foetuses of 180 mm. (crown-rump) length or less the inguinal canal lies parallel to the rectus abdominis rather than to the inguinal ligament.
- The inguinal canal in the female is just as definite and of approximately the same length as in the male foetus of the same age.
Anson, Barry J. (1938). Surg. Gynec. Obstet. 66, 186.
Anson, Barry J. & Cuuster, B. MoVay (1938). Anat. Rec. 70, 211.
Anson, Barry J. & FRANKLIN, L. AsHury (1941). Quart. Bull. Nthwest. Univ. 15, 32.
Aggy, L. B. (1940). Developmental Anatomy, 4th ed., pp. 119, 296. Philadelphia.
CHERNER, MAXWELL (1939). Amer. J. Surg. 44, 593.
Cunninauam (1937). Text-Book of Anatomy, 7th ed. p. 721. Oxford University Press.
Ferxrx, W. (1910). Keibel and Mall’s Human Embryology, 2, 752. Philadelphia. : Grant, J. C. Bomzav (1940). 4 Method of Anatomy, 2nd ed. p. 197. Baltimore.
Gray, Henry (1942). Anatomy of the Human Body, 24th ed. p. 1229. Philadelphia.
Howe, A. Brazier (1939). J. Surg. 6, 653.
Jordan, E. H. & Kindeed, J. E. (1937). Embryology, 3rd ed. p. 299. New York.
Morean, E..H. & Barry, J. Anson (1942). Quart. Bull. Nthwest. Univ. 16, 20.
Morris (1942). Human Anatomy, 10th ed. p. 1331. Philadelphia.
Prersol, Grorce A. (1930). Human Anatomy, 9th ed. p. 523. Philadelphia.
Watson, Leics F. (1938). Amer. J. Surg. 42, 695.
WynpuaM, N. R. (1943). J. Anat., Lond., 77, 179.
Cite this page: Hill, M.A. (2020, August 9) Embryology Paper - The inguinal canal in the foetus and new-born (1944). Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Paper_-_The_inguinal_canal_in_the_foetus_and_new-born_(1944)
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