Paper - A case of atresia ani in a human embryo of 26 mm

From Embryology
Embryology - 18 May 2024    Facebook link Pinterest link Twitter link  Expand to Translate  
Google Translate - select your language from the list shown below (this will open a new external page)

العربية | català | 中文 | 中國傳統的 | français | Deutsche | עִברִית | हिंदी | bahasa Indonesia | italiano | 日本語 | 한국어 | မြန်မာ | Pilipino | Polskie | português | ਪੰਜਾਬੀ ਦੇ | Română | русский | Español | Swahili | Svensk | ไทย | Türkçe | اردو | ייִדיש | Tiếng Việt    These external translations are automated and may not be accurate. (More? About Translations)

Johnson FP. A case of atresia ani in a human embryo of 26 mm. (1914) Anat. Rec., vol. 8, pp. 349-353.

Online Editor  
Mark Hill.jpg
This historic 1914 paper by Franklin Paradise Johnson (1888-1943) describes the abnormal development of the rectum in the 26 mm human embryo. Based on CRL this would make this about a Carnegie stage 22 embryo in week 8.

Also see Johnson's paper on normal rectum development: Johnson FP. The development of the mucous membrane of the oesophagus, stomach and small intestine in the human embryo. (1910) Amer. J Anat., 10: 521-559.
See Johnson's earlier paper on the mucous membrane of the gastrointestinal tract: Johnson FP. The development of the mucous membrane of the oesophagus, stomach and small intestine in the human embryo. (1910) Amer. J Anat., 10: 521-559.
See also Frederic Lewis's 1943 tribute to Johnson: Lewis FT. Clark ER. and Scammon RE. Franklin Paradise Johnson. (1943) Anat. Rec. 86: 1-7.

Week: 1 2 3 4 5 6 7 8
Carnegie stage: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23

Modern Notes:

Stage 22 Links: Week 8 | System Development | Lecture - Limb | Lecture - Head Development | Lecture - Sensory | Science Practical - Head | Science Practical - Sensory | Science Practical - Urogenital | Historic - Skull Development | Carnegie Embryos | Madrid Embryos | Category:Carnegie Stage 22 | Next Stage 23
Week 8, GA week 10, 54 - 56 days, CRL 23 - 28 mm, Carnegie Embryos
  Historic Papers: 1914 | 1954 Stage 19-23
GIT Links: Introduction | Medicine Lecture | Science Lecture | endoderm | mouth | oesophagus | stomach | liver | gallbladder | Pancreas | intestine | mesentery | tongue | taste | enteric nervous system | Stage 13 | Stage 22 | gastrointestinal abnormalities | Movies | Postnatal | milk | tooth | salivary gland | BGD Lecture | BGD Practical | GIT Terms | Category:Gastrointestinal Tract
GIT Histology Links: Upper GIT | Salivary Gland | Smooth Muscle Histology | Liver | Gallbladder | Pancreas | Colon | Histology Stains | Histology | GIT Development
Historic Embryology - Gastrointestinal Tract  
1878 Alimentary Canal | 1882 The Organs of the Inner Germ-Layer The Alimentary Tube with its Appended Organs | 1884 Great omentum and transverse mesocolon | 1902 Meckel's diverticulum | 1902 The Organs of Digestion | 1903 Submaxillary Gland | 1906 Liver | 1907 Development of the Digestive System | 1907 Atlas | 1907 23 Somite Embryo | 1908 Liver | 1908 Liver and Vascular | 1910 Mucous membrane Oesophagus to Small Intestine | 1910 Large intestine and Vermiform process | 1911-13 Intestine and Peritoneum - Part 1 | Part 2 | Part 3 | Part 5 | Part 6 | 1912 Digestive Tract | 1912 Stomach | 1914 Digestive Tract | 1914 Intestines | 1914 Rectum | 1915 Pharynx | 1915 Intestinal Rotation | 1917 Entodermal Canal | 1918 Anatomy | 1921 Alimentary Tube | 1932 Gall Bladder | 1939 Alimentary Canal Looping | 1940 Duodenum anomalies | 2008 Liver | 2016 GIT Notes | Historic Disclaimer
Human Embryo: 1908 13-14 Somite Embryo | 1921 Liver Suspensory Ligament | 1926 22 Somite Embryo | 1907 23 Somite Embryo | 1937 25 Somite Embryo | 1914 27 Somite Embryo | 1914 Week 7 Embryo
Animal Development: 1913 Chicken | 1951 Frog

Historic Embryology Textbooks

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

A case of Atresia Ani in a Human Embryo of 26 mm

Franklin Paradise Johnson

The Anatomical Laboratory of the University of Missouri

One Figure

Among the most common anomalies of the rectum are those of atresia ani, atresia recti, and atresia ani et recti. The first of these is described as being present when an anal opening is lacking. An anal invagi.nation may or may not be present, or the site of the anus may be marked by a surface elevation. In atresia recti simplex the anal opening is present and normally developed, but the upper part of the rectum, failing to unite with the anal portion, ends blindly in the pelvis. In atresia ani et recti, both anal opening and a portion of the ampulla recti are missing. These simple atresiae may be complicated by the additional anomalous conditions of fistulae into the urethra, bladder, vagina, vulva, or through the scrotum and perineum.

Such anomalies of the rectum, which are usually detected at the time of birth or shortly afterward, have aroused considerable interest, and various theories have arisen as to their probable origin. Among those who have studied the causes of rectal anomalies should be mentioned the names of Rotter ('03) and Jones (’04).

However correct any of the theories regarding the formation of these atresiae may be, before they can be definitely accepted, they demand not only a correct knowledge of the normal development of of these parts, but direct evidence concerning the time and manner of deviation from the normal. It is because of this that the present atresia, found at a comparatively early stage of the embryo, is described. Although the author knows of no other case of this kind found in an embryo, the observation which Keibel made on an embryo of 11.5 mm. should be mentioned. He found that the lumen of the rectum in its lower part had become occluded at two small places. The observation, however, offers no evidence, direct or indirect, that this would develop into a case of atresia. It seems probable that the lumen might have again opened up, for in corresponding stages of pig and rabbit embryos (Lewis ’03) and of chick embryos (Minot ’00), where there is normally an epithelial occlusion of the rectum, such reopening occurs. It should also be recalled that epithelial occlusion occurs normally in the developing duodenum (Tandler ’O(), Johnson ’10).

Johnson1914b fig01.jpg

Fig. 1 Graphic reconstruction of the pelvis of a human embryo of 26 mm. (H 99). all., allantois; amp.7“ec., ampulla recti; bul.a., blindly ending bulbus analis; d, lfliillerian and Wolffian ducts; (7.1. and ('.IV, first and fourth coccygeal vertebrae; SJ, first sacral vertebra.

The case of atresia under consideration (see accompanying figure) was found in Embryo H 99 of Prof. C. M. Jackson’s collection, the crown—rump length of which is 26 mm. The sections were cut transversely to the long axis of the embryo, hence the plane of sectioning through the lower part of the rectum is longitudinal. The upper part of the rectum is apparently normal. Its epithelial tube has a transverse diameter of 0.23 mm. and is composed of two to three layers of cells. More caudally the rectal tube expands, forming what has been termed in a former paper (Johnson ’14) the bulbus analis. This has a transverse diameter of 0.29 mm. at its widest place and its epithelium is of about the same thickness. A single deep infolding extends itself along the ventral Wall of the tube. The epithelium of the upper part of the bulbus analis is regular, its nuclei are closely packed and distinct, but cell boundaries are not distinguishable. At about the middle of the bulbus analis the epithelium becomes broken up, and from this point caudally becomes more and more irregular. In this region the nuclei are more scattered and in places less sharply outlined than above. The lumen becomes gradually filled up with broken-off pieces of the epithelium, and lower down becomes lost in a mass of epithelial debris. The lower portion of the bulbus analis is smaller in size, and finally disappears from View altogether. The last remnants are seen as a few nuclei scattered about in the mesenchyma. The epidermis of the anal region is found about 0.55 mm. caudad to these last remnants. An anal invagination is present but it is Very shallow.

Surrounding the epithelial tube throughout its whole length is mese-nchyma. In the upper part of the bulbus analis this lies close to the epithelium, but in the lower part, where the epithelium is broken down, the mesenchyma is separated from it by a distinct shrinkage space. At the termination of the epithelium the shrinkage space again disappears. Between the lower end of the rectum and the anal invagination, the mesenchyma shows no special features. It is possible that some of the nuclei seen in the rnesenchyma of this region belong to the epithelium, but this point is not determinable.

The inner circular and the outer longitudinal layers of the muscularis are distinct. They terminate a short distance above the last remnants of the epithelium. As has been formerly shown (Johnson ’14) the circular muscle coat terminates normally at the constriction between the bulbus analis and the bulbus terminalis. This affords a means of determining that the last portions of the epithelium represent a part of the bulbus terminalis.

In front or ventral to the rectum is seen the urogenital sinus, which at this stage is quite widely separated from the rectal tube. Opening into it are seen the united Mullerian ducts and on either side, the two Wolflian ducts, although their epithelia are somewhat broken up and irregular. The ureters do not join the urogenital sinus but end blindly, their epithelium being broken down in a similar manner to that of the rectum.

The results of my work on the development of the normal rectum have shown that the bulbus analis and the bulbus terminalis go into the formation of the zona columnaris and zona intermedia of the pars analis recti respectively. Since in this anomalous embryo the epithelium of the rectum terminates in the region of the bulbus terminalis, it is evident that the missing portion of the rectal tube represents what would have normally been the zona intermedia. The anomaly should, therefore, be classified as a case of atresia ani simplex. However, owing to the peculiar disposition of the ureters, it is doubtful Whether it would have retained its simple relations, had the embryo lived longer.

Regarding the cause of this anomaly little can be definitely said. It is doubtful whether the anal membrane is in any way concerned. In an examination of 19 embryos of 15.5 mm. and over, Keibel and Elze (’08) show that in stages of 15.5, 16, 17, 18, 18, 18.5, 19.5, 20, 20, 20, 20, 20.5, 22, 22.5, 24, 24, 26 and 26 mm. the anal membrane was present and the anal passage closed to the outside, while in only one case (22.5 mm.) was the passage open. Broman (’11) states that an anal opening is not effected until the embryo is about 33 mm. in length. The results of my own work show that the anal membrane is present in embryos of 17, 19 and 22.8 mm. and has disappeared in those of 16, 29, 30, 30 and 31 mm. and above. From these observations it will be seen that usually at 26 mm. the anal membrane occludes the anal passage, so that the above anomaly cannot be explained by a failure of the anal membrane to break down normally. Constriction and a subsequent breaking apart of the epithelial cord at this place must have occurred.


BROMAN, I. 1911 Normale und abnorme Entwicklung des Menschen. Wiesbaden.

Johnson FP. The development of the mucous membrane of the oesophagus, stomach and small intestine in the human embryo. (1910) Amer. J Anat., 10: 521-559.

Johnson FP. The development of the rectum in the human embryo. (1914) Amer. J Anat. 16(1): 1-58.

Woods-Jones F. The nature of the malformations of the rectum and urogenital passages. (1904) Br. Med. J. 1630-1634.

Keibel F. and Elze C. Normal Plates of the Development of the Human Embryo (Homo sapiens). (1908) Vol. 8 in series by Keibel F. Normal plates of the development of vertebrates (Normentafeln zur Entwicklungsgeschichte der Wirbelthiere) Fisher, Jena., Germany.

Lewis FT. The gross anatomy of a 12 mm pig. (1903) Amer. J Anat. 2: 221-225.

Minot CS. On the solid stage of the large intestine in the chick. (1900) Jour. Boston Soc. Med. Sci. 4: 153-164.

ROTTER, J. 1903 Die Krankheiten des Mastdarms und des Afters; in the Handbuch der pracktischen Chirurgie by Bergmann et al.

TANDLER, J. 1900 Zur Entwickelungsgeschichte des Menschlichen Duodenum in friihen Embryonalstadien. Morph. Jahrb., Bd. 29, pp. 187-216.

Cite this page: Hill, M.A. (2024, May 18) Embryology Paper - A case of atresia ani in a human embryo of 26 mm. Retrieved from

What Links Here?
© Dr Mark Hill 2024, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G