FEATURES OF DEVELOPMENT AND FORMATION TOPOGRAPHIES OF THE VESICO-UMBILICAL TRIANGLE IN THE PRENATAL PERIOD OF HUMAN ONTOGENESIS

Abstract

On the front abdominal wall, there is a section of the vesico- umbilical triangle, which is bounded on the sides by the umbilical arteries, and below by the bladder. In the available sources of scientifi c literature, there is practically no information on the patterns of prenatal morphogenesis and the formation of the topography of the area of the vesico- umbilical triangle of a person. However, accurate knowledge of the topography of the constituent formations of the vesico- umbilical triangle determines the choice of incision during operations and provides a theoretical explanation for the occurrence of various pathological conditions: umbilical, postoperative ventral hernias, abdominal cavity organ eventration, and the spread of purulent- infl ammatory processes.The purpose of the study was to clarify the features of prenatal morphogenesis and topographical- anatomical relationships of the vesico- umbilical triangle of a person.The study was conducted on the preparations of 7 embryos of 4-6 weeks, 14 pre-fetuses of 7-12 weeks, and 26 human fetuses aged from 4 to 10 months using the production of a series of histological sections, microscopy, macromicroscopic preparation, and injection of vessels.In embryos of 4.5-5.5 mm parietal- coccygeal length (PCL), the allantois is located in the direction of the abdominal wall, connecting with other structures in the area of the future umbilical ring. In the mesoderm of the allantois, there is a layer of vessels that form a system of umbilical vessels. On frontal sections of 10.5-12.0 mm PCL embryos, narrowing of the allantois duct is observed: a more gradual narrowing near the umbilical ring, and a sharper one closer to the cloaca. At this stage of embryogenesis, there is a clear division of the cloaca into ventral (urogenital sinus) and dorsal (rectal lining) sections.It was established that the bladder is formed from two sources – the body and top – from the caudal part of the allantois, the bottom, and neck – from the pelvic part of the genitourinary sinus. In the 3rd month of intrauterine development, the middle and deep layers of the vesico- umbilical triangle are formed, which are represented by the sheath of the rectus abdominis muscle, rectus and pyramidal muscles, prostatic and allantoic leaves. Fascial spurs, departing from the latter, divide the prostate space into four interfascial slits. The surface layer of the vesico- umbilical triangle is still poorly diff erentiated at this stage of intrauterine development. At the end of the 4th month of intrauterine development, the surface fascia of the vesico- umbilical triangle is formed as independent formations. During macro- microscopic dissection of the area of the vesico- umbilical triangle in 6-month-old fetuses, in addition to the fascial formations of the superfi cial layer, all the structures of the deep layer can be distinguished: the transverse fascia, the vestibular and allantoic fascial sheets, as well as two fascial spurs that divide the vestibular space into four interfascial gaps. From our point of view, it is appropriate to call the prostatic fascia and prostatic fi brous space vesico- umbilical.