File:Patten046ad.jpg

Fig. 46. Diagrams of transverse sections four-day chick

Fig. 46. A-D | Fig. 46. E-H The location of the sections is indicated on a small outline sketch of the entire embryo.

Although the urinary system is not at this stage developed to conditions which resemble those in the adult the parts of it which have been established are already definitely associated with the cloaca. The proximal portion of the allantoic stalk which is the homologue of the urinary bladder of mammals opens directly into the cloaca (Fig. 43). When the urinary system of the embryo is considered, we shall see that the ducts which drain the developing excretory organs also open into the cloacal region on either side of the allantoic stalk.

There is at this stage but little indication of the formation of the gonads. The relation of the sexual ducts to the cloaca can be made out only by the study of older embryos.

Links: Introduction | Gametes and Fertilization | Segmentation | Entoderm | Primitive Streak and Mesoderm | Primitive Streak to Somites | 24 Hours | 24 to 33 Hours | 33 to 39 Hours | 40 to 50 Hours | Extra-embryonic Membranes | 50 to 55 Hours | Day 3 to 4 | References | All Figures

Historic Disclaimer - information about historic embryology pages

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)

Reference

Patten BM. The Early Embryology of the Chick. (1920) Philadelphia: P. Blakiston's Son and Co.

Cite this page: Hill, M.A. (2024, April 27) Embryology Patten046ad.jpg. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/File:Patten046ad.jpg

What Links Here?

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