Development of the Corpus Vasculare Paracloacale in the Male Chick Embryo

Abstract

The development of the corpus vasculate paracloacale (CVP) was described in the male chick embryo. The beginning of formation of the organ was indicated by an accumulation of mesenchymal cells accompanying blood vessels and nerves on the seventh day of incubation. Three stages were distinguished: The first stage extended from the seventh to eighth day of incubation when the primordium, which was a mass of mesenchymal cells, continued to increase in size without differentiation of lymphatic vessels. The second stage was observed from the ninth to twelfth day of incubation when blood vessels were formed earlier and lymphatic spaces a little later. In the third stage, or on and after the fourteenth day of incubation, the formation of capillary cords began, accompanied with the development of internal lymphatic spaces. The components of the CVP, including capsule, trabecula, capillary cord, and peripheral and internal lymphatic spaces, developed by the sixteenth day of incubation.