Septation and differentiation of the embryonic human cloaca

BACKGROUND/PURPOSE

Limitations in methodologies have fostered controversy regarding the septation of the human embryonic cloaca. The aim of this study was to evaluate the septation of the human embryonic cloaca.

METHODS

Using the Carnegie Embryological Collection and specimens at Johns Hopkins, Baltimore, MD, the authors studied 12 embryos and five fetuses. Embryo photomicrographs were reconstructed using three-dimensional modeling.

RESULTS

In Carnegie stage 13 the authors observed a cloaca, distinct primitive urogenital sinus, and anorectum separated by the urorectal septum. The primitive urogenital sinus and anorectum enter the cloaca separated from the amniotic space by the cloacal membrane. As the embryo becomes a fetus it lengthens, grows, expands and rotates through a process called transformation. Transformation gives rise to a loss of caudal curvature and a decrease in distance between the septum and membrane, but these structures do not fuse. Disintegration of the cloacal membrane produces openings for the urogenital sinus and anorectum.

CONCLUSIONS

The observations suggest that the urogenital sinus and anorectum form early and are separated by the urorectal septum as a passive structure. There does not appear to be septation or differentiation of the cloaca itself.

Coming into the electronic age

This paper is the culmination of 5 years of change in the Pathology Photography and Graphics Arts Department at the Johns Hopkins University and School of Medicine. We are no longer a photographic and art department; we have changed to a high technology electronic image department and are looking to the future. In order for us to compete in the new medical care field, we will change and are changing daily to serve our customers. We believe the changes will be made, and will continue to keep up with new technology, to the advantage of customers and employees.

User's review of the Canon Colour Copier

The ability to link the new Canon Colour Laser Copier to a computer opens up new boundaries of data manipulation. A report from the user's point of view, describes a system comprising the copier with computer input, slide scanner and flat copy capacity. Information is given on the types of materials produced, the types of users, the cost of purchase and maintenance, and the potential for generating profit.

Automation and cost recovery in a biomedical communications department

The current demands on the modern biomedical communications department are to provide a faster and better service and, at the same time, keep costs to a minimum. One way of tacking this problem is to automate production procedures and record keeping, using the latest technology. An account is given of how the department in The Johns Hopkins University School of Medicine is successfully addressing this problem.

A start to a cost recovery system

Some basic guidelines are given on how to plan and implement a cost recovery system. The information is based on practical experience, the author having successfully incorporated such a system 21 years ago.

Computed tomography of intracranial extramedullary hematopoiesis

Patients with extramedullary hematopoiesis may be divided into two main groups. The first group shows paraosseous foci that may result from "herniation" of medullary tissue from the underlying bone. This is seen in hemolytic disorders where the marrow has tremendous activity. The second group shows extraosseous soft tissue foci, which may arise from multipotential stem cells. This occurs when the marrow activity is ineffectual, as in the myeloproliferative disorders or, rarely, with toxic or tumoral marrow destruction. We present a patient with myelosclerosis and four intracranial masses of hematopoietic tissue in the subdural space. We believe this is the first description of the cranial CT findings in this condition.