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Quarterly Journal of Microscopical Science, Vol s2-75, 151-163, Copyright © 1932 by Company of Biologists

Memoirs: The Origin and Development of the Anterior Lymph-Sacs in the Sea-Turtle (Thalassochelys caretta)

E. R. van der Jagt 1

1 University of Iowa

1. In the lymph-sac area of embryos at the end of the second week of development the mesenchyme is very compact, showing slight signs of vacuolation. The area is bounded by the anterior cardinal vein and its dorsal branches, the wide meshed superficial plexus and the ventro-lateral branches of the cardinal vein. Within this area the lymph-sac anlagen first appear, lying in the angle between the dorso-lateral branches and the cardinal vein itself.

2. The dorsal tributaries of the pre-cardinals are concerned in the development of the lymph-sacs. In the mesenchyme surrounding these tributaries isolated spaces develop in direct connexion with the veins.

3. The development of the anterior lymph-sacs in the seaturtle is initiated by vacuolation of the mesenchyme in the region of the cardinal tributaries during the middle part of the third week of development.

4. A series of channels is formed from the anterior cardinal tributaries and isolated spaces which in their greatest development exist as plexuses of vessels connected with the cardinal veins.

5. These channels enlarge and fuse with each other, the remnants of their walls appearing as protoplasmic fibres in the lumen, producing a system of cavities very irregular in size and shape. They inter-communicate and connect at the same time with the dorsal tributaries of the pre-cardinal veins. The mesenchyme cells surrounding these cavities are gradually transformed to the flattened endothelial cells which later line the sacs.

6. The lymph-sac is well developed at twenty-four days. Fusion and enlargement of individual cavities has continued up to this time.

7. As the development of the lymph-sacs proceeds they lose connexion with the cardinal veins except for the opening at the posterior end of the sac.

8. The development of the anterior lymph-sacs in the turtle shows two distinct anlagen, one from the mesenchyme and the other from the venous tributaries, which unite to form the veno-lymphatics. The increase in size and confluence of the veno-lymphatics determines the development of the anterior lymph-sacs.






© The Company of Biologists Ltd 1932