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W B Robertson

Publications and source records attributed to W B Robertson.

64 records · Page 4Linked to original sources
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Placenta creta and placenta praevia creta.

The placental bed in placenta creta and placenta praevia creta was studied from pregnancy or immediate postpartum hysterectomy specimens. In all cases placental villi were seen in direct contact with myometrium, the sine qua non of placenta creta, but was focal in some cases. There was no apparent diminution of decidua parietalis or, in cases of focal accreta, of adjacent basalis. In all cases the extravillous trophoblast was mainly uninuclear or binuclear, in contrast to the placental bed syncytial giant cells seen in late normal placentation. There was an apparent proliferation of interstitial trophoblast at the junction of placenta with myometrium, but the density of interstitial trophoblast deeper in the myometrium was lower than it is in normal placentation. An unusual uteroplacental vasculature was seen in which physiological changes were present in large arteries of the radial/arcuate system deep in the myometrium, while there were also spiral arteries more superficially without physiological changes. These findings suggest that in placenta creta there is defective interaction between maternal tissues, particularly decidua, and migratory trophoblast in the early stages of placentation resulting in undue adherence of the placenta or penetration into the uterus coupled with the development of an abnormal uteroplacental circulation.

Arteries↗
PubMedDate not supplied

Trophoblastic invasion of human decidua from 8 to 18 weeks of pregnancy.

Trophoblastic invasion of the human decidua has been studied in 48 intact uteri with pregnancies ranging from 8 to 18 weeks after the last menstrual period. Some cytotrophoblast invades the distal segments of the spiral arteries to become endovascular while the rest diffusely infiltrates the decidua as an interstitial invader. The interstitial cytotrophoblast reaches the myometrium and gives rise to the characteristic placental bed giant cells. As the placental site enlarges the lateral spiral arteries come to lie obliquely; new openings into the intervillous space are created but this readjustment of the placental blood supply may cause focal superficial decidual necrosis. The physiological changes converting the spiral to the uteroplacental arteries are effected in the upper decidua by the action of endovascular and perivascular cytotrophoblast, whereas in the deeper decidua endovascular trophoblast is principally involved. Endometrial granulocytes aggregate in the region of maternal tissue degeneration with the heaviest trophoblast invasion but the role played by these cells in placentation is unknown.

Arteries↗
PubMedDate not supplied

The pattern of interstitial trophoblastic invasion of the myometrium in early human pregnancy.

The human placental bed myometrium, studied in 42 intact hysterectomy specimens ranging from 8 to 18 weeks' gestation, is characterized by the presence of large numbers of non-villous invasive cytotrophoblastic cells. Quantitative morphometric analysis reveals a tendency for maximal invasive activity to occur at the centre and, subsequently, to extend centrifugally to produce an annular pattern. Morphological observations suggest that the intimate mixture of cytotrophoblast with myometrial tissue must affect the mechanical properties of the myometrium. Local hormone production by trophoblast may induce or enhance these and other changes in uterine tissues that are essential for the establishment of human placentation. Cytotrophoblastic invasion into the myometrium appears to be restricted to the earlier stages of gestation and morphological evidence indicates that, subsequently, clumps of cytotrophoblast fuse to form multinuclear syncytiotrophoblast, the characteristic placental bed giant cells.

Female↗
PubMedDate not supplied

Review article: trophoblast invasion and the establishment of haemochorial placentation in man and laboratory animals.

Trophoblast invasion is an essential component of haemochorial placentation and has to be considered to relation to reactive changes in the maternal uterine tissues. Some comparative aspects of human and laboratory rodents are discussed and, although there is an obvious phylogenetic gap between the two, many characteristics of placental development are found to be analogous. Trophoblast growth into the uterus is different in different species: localized trophoblast growth forming a bulky tissue (mouse, rat, hamster) contrast with a dispersion of independent trophoblastic elements, forming an interstitial invasion (guinea pig, man). In the rat, mouse, hamster and man retrograde intra-arterial trophoblast migration occurs in maternal vessels supplying blood to the developing placenta. Early changes in maternal tissue might influence trophoblast behaviour. Decidualization probably is a key phenomenon, and the relation of decidual necrosis to trophoblast invasion is considered. Some kind of controlled immune response by the mother also may be involved. These considerations apply to stromal or interstitial invasion as well as to intravascular trophoblast migration but, for the latter, haemodynamic factors probably influence tissue reactions.

Adaptation, Physiological↗
PubMedDate not supplied

Uteroplacental arterial changes related to interstitial trophoblast migration in early human pregnancy.

Morphometric and statistical techniques were used to assess the relation of myometrial interstitial trophoblast to the uteroplacental vasculature in 27 intact hysterectomy specimens ranging from 8 to 18 weeks' gestation. It was found that the volume density of cytotrophoblast in the myometrium and in particular the proximity of such trophoblast to the placental bed spiral arteries correlated significantly with morphological alterations in these vessels. The changes included swelling of endothelium, hypertrophy of individual medial smooth muscle cells, and oedema and disruption of the architecture of the vessel wall as a time-related continuum. Some of the changes, such as swollen endothelium and basophilia of medial smooth muscle cells were noted also in spiral arteries in the non-placental bed endometrium but to a considerably less extent than in the placental bed. Intimal vacuolation was common to placental bed and non-placental bed arteries, increased with gestational age and can be considered as a non-specific feature. The migration of endovascular trophoblast into the myometrial spiral arteries in the second trimester occurred only when these arteries had been considerably altered in their morphology. These findings indicate that migratory interstitial cytotrophoblast probably has a role to play in the preparation of the myometrial segments of the uteroplacental arteries for the second wave of endovascular trophoblast migration that occurs in the second trimester of human pregnancy.

Arteries↗