«At the bifurcation of the aorta, the middle sacral artery arises posteriorly and travels on the pelvic surface of the sacrum to supply branches to the sacral foramina and the rectum. The common iliac arteries arise at the level of the fourth lumbar...» Document abstract
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SummaryAt the bifurcation of the aorta, the middle sacral artery arises posteriorly and travels on the pelvic surface of the sacrum to supply branches to the sacral foramina and the rectum. The common iliac arteries arise at the level of the fourth lumbar vertebra, run anterior and lateral to their accompanying veins, and bifurcate into the external and internal iliac arteries at the SI joint. The external iliac artery follows the medial border of the iliopsoas muscle along the arcuate line and leaves the pelvis beneath the inguinal ligament as the femoral artery. Its inferior epigastric artery is given off proximal to the inguinal ligament and ascends medial to the internal inguinal ring to supply the rectus muscle and overlying skin. Because the rectus is richly collateralized from above and laterally, the inferior epigastric arteries may be ligated with impunity. A rectus myocutaneous flap based on this artery has been used to correct major pelvic and perineal tissue defects. Near its origin, the inferior epigastric artery sends a deep circumflex iliac branch laterally and a pubic branch medially. Both vessels travel on the iliopubic tract and may be injured during inguinal hernia repair. Its cremasteric branch joins the spermatic cord at the internal inguinal ring and forms a distal anastomosis with the testicular artery. In 25% of people, an accessory obturator artery arises from the inferior epigastric artery and runs medial to the femoral vein to reach the obturator canal. This vessel must be avoided during obturator lymph node dissection.
«Surgical Anatomy of the Retroperitoneum, Kidneys, and Ureters; only the pelvic courses of its nerves are reviewed here. The iliohypogastric nerve (L1) travels between, and supplies, the internal oblique and the transversus muscles and pierces the...» Document abstract
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SummarySurgical Anatomy of the Retroperitoneum, Kidneys, and Ureters; only the pelvic courses of its nerves are reviewed here. The iliohypogastric nerve (L1) travels between, and supplies, the internal oblique and the transversus muscles and pierces the internal and external oblique muscles 3 cm above the external inguinal ring to supply sensation over the lower anterior abdomen and pubis. The ilioinguinal nerve (L1) passes through the internal oblique muscle to enter the inguinal canal laterally. It travels anterior to the cord and exits the external ring to provide sensation to the mons pubis and anterior scrotum or labia majora. The genitofemoral nerve (L1, L2) pierces the psoas muscle to reach its anterior surface in the retroperitoneum and then travels to the pelvis and splits into genital and femoral branches. The latter supplies sensation over the anterior thigh below the inguinal ligament. The genital branch follows the cord through the inguinal canal, supplies the cremaster muscle, and supplies sensation to the anterior scrotum.
«The pelvic bones are the sacrum (the termination of the axial skeleton) and the two innominate bones. The latter are formed by the fusion of the iliac, ischial, and pubic ossification centers at the acetabulum. The ischium and pubis also meet below,...» Document abstract
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SummaryThe pelvic bones are the sacrum (the termination of the axial skeleton) and the two innominate bones. The latter are formed by the fusion of the iliac, ischial, and pubic ossification centers at the acetabulum. The ischium and pubis also meet below, in the center of the inferior ramus, to form the obturator foramen. The weight of the upper body is transmitted from the axial skeleton to the innominate bones and lower extremities through the strong sacroiliac (SI) joints. As a whole, the pelvis is divided into a bowl-shaped false pelvis, formed by the iliac fossae and largely in contact with intraperitoneal contents, and the circular true pelvis wherein lie the urogenital organs. At the pelvic inlet, the true and false pelves are separated by the arcuate line, which extends from the sacral promontory to the pectineal line of the pubis. The lumbar lordosis that accompanies erect posture tilts the axis of the pelvic inlet so that it parallels the ground; the pelvic inlet faces anteriorly, and the inferior ischiopubic rami lie horizontal. When approaching the pelvis through a low midline incision, the surgeon gazes directly into the true pelvis.
«The amnion at term is a tough and tenacious but pliable membrane. It is the innermost fetal membrane and is contiguous with the aminonic fluid. This particular avascular structure occupies a role of incredible importance in human pregnancy. In many...» Document abstract
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SummaryThe amnion at term is a tough and tenacious but pliable membrane. It is the innermost fetal membrane and is contiguous with the aminonic fluid. This particular avascular structure occupies a role of incredible importance in human pregnancy. In many obstetrical populations, preterm premature rupture of the fetal membranes is the single most common antecedent of preterm delivery. The amnion is the tissue that provides almost all of the tensile strength of the fetal membranes. Therefore, the development of the component(s) of the amnion that protects against rupture or tearing is vitally important to successful pregnancy outcome.
«Because the placenta functionally represents a rather intimate association of the fetal capillary bed to maternal blood, its gross anatomy primarily concerns vascular relations. The fetal surface of the placenta is covered by the transparent amnion...» Document abstract
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SummaryBecause the placenta functionally represents a rather intimate association of the fetal capillary bed to maternal blood, its gross anatomy primarily concerns vascular relations. The fetal surface of the placenta is covered by the transparent amnion beneath which the fetal chorionic vessels course. A section through the placenta in situ includes amnion, chorion, chorionic villi and intervillous spaces, decidual plate, and myometrium. The maternal surface of the placenta is divided into irregular lobes by furrows produced by septa, which consist of fibrous tissue with sparse vessels confined mainly to their bases. The broad-based septa ordinarily do not reach the chorionic plate, thus providing only incomplete partitions.
«From the electron microscopic studies of Wislocki and Dempsey (1955), data were provided that permitted a functional interpretation of the fine structure of the placenta. There are prominent microvilli on the syncytial surface, corresponding to the...» Document abstract
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SummaryFrom the electron microscopic studies of Wislocki and Dempsey (1955), data were provided that permitted a functional interpretation of the fine structure of the placenta. There are prominent microvilli on the syncytial surface, corresponding to the "brush border" described by light microscopy. Associated pinocytotic vacuoles and vesicles are related to the absorptive and secretory placental functions. The inner layer of the villi—the cytotrophoblasts—persists to term, although often compressed against the trophoblastic basal lamina, and retains its ultrastructural simplicity.
«In a description of the earliest stages of the human blastocyst, the wall of the primitive blastodermic vesicle was characterized as consisting of a single layer of ectoderm. As early as 72 hours after ovum fertilization, the 58-cell blastula had...» Document abstract
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SummaryIn a description of the earliest stages of the human blastocyst, the wall of the primitive blastodermic vesicle was characterized as consisting of a single layer of ectoderm. As early as 72 hours after ovum fertilization, the 58-cell blastula had differentiated into 5 embryo-producing cells and 53 cells destined to form trophoblasts (Hertig, 1962). Although trophoblasts have not been distinguished before blastocyst implantation, both cytotrophoblasts and syncy-tiotrophoblast are present in the earliest implanted blastocyst of the monkey. Indeed, evidence has been presented that chorionic gonadotropin (hCG) is secreted by cells of the human blastocyst at the time of implantation.
«Over the last half century, many attempts to explain the survival of the semiallogenic fetal graft have been proposed. One of the earliest explanations was based on the theory of antigenic immaturity of the embryo-fetus. This was disproved by...» Document abstract
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SummaryOver the last half century, many attempts to explain the survival of the semiallogenic fetal graft have been proposed. One of the earliest explanations was based on the theory of antigenic immaturity of the embryo-fetus. This was disproved by Billingham (1964) who showed that transplantation (HLA) antigens are demonstrable very early in embryonic life. The trophoblasts are the only cells of the conceptus in direct contact with maternal tissues or blood and these tissues are genetically identical with fetal tissues. Another explanation was based on diminished immunological responsiveness of the pregnant woman. There is, however, no evidence for this to be other than an ancillary factor. In a third explanation, the uterus (decidua) is proposed as an immunologically privileged tissue site. Clearly, transplantation immunity can be evoked and expressed in the uterus as in other tissues. Therefore, the acceptance and the survival of the conceptus in the maternal uterus must be attributed to an immunological peculiarity of the trophoblasts, not the decidua.
«The extravillous and villous trophoblasts are the embryonic-fetal tissues of the anatomical interface of the placental arm; the avascular fetal membranes—the amnion and chorion laeve—are the fetal tissues of the anatomical interface of the paracrine...» Document abstract
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SummaryThe extravillous and villous trophoblasts are the embryonic-fetal tissues of the anatomical interface of the placental arm; the avascular fetal membranes—the amnion and chorion laeve—are the fetal tissues of the anatomical interface of the paracrine arm of this system.
The placental arm of this system links the mother and fetus as follows: maternal blood (spurting out of the uteroplacental vessels) directly bathes the syncytiotrophoblast, the outer surface of the trophoblastic villi; fetal blood is contained within fetal capillaries, which traverse within the intravillous spaces of the villi. This is a hemochorioendothelial type of placenta. The paracrine arm of this system links the mother and fetus through the anatomical and biochemical juxtaposition of (extraembryonic) chorion laeve and (maternal uterine) decidua parietalis tissue.
The placental arm of this system links the mother and fetus as follows: maternal blood (spurting out of the uteroplacental vessels) directly bathes the syncytiotrophoblast, the outer surface of the trophoblastic villi; fetal blood is contained within fetal capillaries, which traverse within the intravillous spaces of the villi. This is a hemochorioendothelial type of placenta. The paracrine arm of this system links the mother and fetus through the anatomical and biochemical juxtaposition of (extraembryonic) chorion laeve and (maternal uterine) decidua parietalis tissue.
«This tissue is the specialized, highly modified endometrium of pregnancy. The transformation of secretory endometrium to decidua is dependent upon the action of estrogen and progesterone and other stimuli provided by the implanting blastocyst (or...» Document abstract
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SummaryThis tissue is the specialized, highly modified endometrium of pregnancy. The transformation of secretory endometrium to decidua is dependent upon the action of estrogen and progesterone and other stimuli provided by the implanting blastocyst (or maternal platelets) during trophoblast invasion of the endometrium and its blood vessels. The special relationship that exists between the endometrium/decidua and the invading trophoblast seemingly defies the laws of transplantation immunology. The success of this unique autograft is not only a scientific curiosity but may involve processes that harbor insights into more successful transplantation surgery and perhaps the control of neoplasia as well.
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