Talk:Placenta Development

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Placenta Issue

Vol. 54 Nos. 2/3 (2010)

http://www.ijdb.ehu.es/web/contents.php?vol=54&issue=2-3

Anthropometry of fetal vasculature in the chorionic plate

Gordon Z, Elad D, Almog R, Hazan Y, Jaffa AJ, Eytan O. J Anat. 2007 Dec;211(6):698-706. Epub 2007 Oct 30. PMID: 17973911

http://onlinelibrary.wiley.com/doi/10.1111/j.1469-7580.2007.00819.x/full

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2697319/figure/fig1/

A photomicrograph of the human endometrium on the fourth day of menstruation showing an eroded spiral artery (arrowed) projecting freely into the uterine lumen. b) A photomicrograph of spiral arteries in a rhesus monkey during the phase of ovulation injected with India ink in gelatin. The arrow marks the endometrial–myometrial boundary, and a marked constriction (asterisked) can be seen in the spiral artery in the junctional zone just below. c) Reconstruction from serial sections of a converted spiral artery passing through the myometrium (M) and endometrium (E) before opening into the intervillous space through the basal plate of a term placenta. The widest dimension of the opening is given as 2.4 mm. Reproduced from Refs. [83], [15] and [16] respectively with permission of the Carnegie Institute of Washington.

Immunology of placentation in eutherian mammals

http://www.nature.com/nri/journal/v6/n8/full/nri1897.html

The human placenta is a hematopoietic organ during the embryonic and fetal periods of development

http://www.ncbi.nlm.nih.gov/pubmed/19073167

"We studied the potential role of the human placenta as a hematopoietic organ during embryonic and fetal development. Placental samples contained two cell populations-CD34(++)CD45(low) and CD34(+)CD45(low)-that were found in chorionic villi and in the chorioamniotic membrane. CD34(++)CD45(low) cells express many cell surface antigens found on multipotent primitive hematopoietic progenitors and hematopoietic stem cells. CD34(++)CD45(low) cells contained colony-forming units culture (CFU-C) with myeloid and erythroid potential in clonogenic in vitro assays, and they generated CD56(+) natural killer cells and CD19(+)CD20(+)sIgM(+) B cells in polyclonal liquid cultures. CD34(+)CD45(low) cells mostly comprised erythroid- and myeloid-committed progenitors, while CD34(-) cells lacked CFU-C. The placenta-derived precursors were fetal in origin, as demonstrated by FISH using repeat-sequence chromosome-specific probes for X and Y. The number of CD34(++)CD45(low) cells increased with gestational age, but their density (cells per gram of tissue) peaked at 5-8 wk, decreasing more than sevenfold at the onset of the fetal phase (9 wk of gestation). In addition to multipotent progenitors, the placenta contained myeloid- and erythroid-committed progenitors indicative of active in situ hematopoiesis. These data suggest that the human placenta is an important hematopoietic organ, raising the possibility of banking placental hematopoietic stem cells along with cord blood for transplantation."

De novo synthesis of estrogen in pregnant uterus is critical for stromal decidualization and angiogenesis. Das A, Mantena SR, Kannan A, Evans DB, Bagchi MK, Bagchi IC. Proc Natl Acad Sci U S A. 2009 Jul 28;106(30):12542-7. Epub 2009 Jul 20. Erratum in: Proc Natl Acad Sci U S A. 2009 Sep 15;106(37):16003. PMID: 19620711 | PNAS

• Implantation is initiated when the embryo attaches to the uterine luminal epithelium during early pregnancy.
• Following this event, uterine stromal cells undergo steroid hormone-dependent transformation into morphologically and functionally distinct decidual cells in a unique process known as decidualization.
• An angiogenic network is also formed in the uterine stromal bed, critically supporting the early development of the embryo.
• ovarian progesterone as a key regulator of decidualization is well established
• these studies in mice - identified the decidual uterus as a novel site of estrogen biosynthesis and uncovered estrogen-regulated maternal signaling pathways that critically control uterine differentiation and angiogenesis during early pregnancy.

Classification of human placental stem villi: review of structural and functional aspects

Microsc Res Tech. 1997 Jul 1-15;38(1-2):29-41.

Demir R, Kosanke G, Kohnen G, Kertschanska S, Kaufmann P.

Department of Histology and Embryology, Medical Faculty, Akdeniz University, Antalya, Turkey. Abstract The stem villi of the human placenta represent the central branches of the villous trees. They are characterized by a condensed fibrous stroma in which the fetal arteries and veins as well as the arterioles and venules are embedded. Functionally they are accepted as the mechanically supporting structures of the villous trees, and they are supposed to control fetal blood flow to the maternofetal exchange area, which is located in the peripheral villi. To obtain further insights into the functions of the stem villi, the recent literature has been reviewed, and some immunohistochemical, ultrastructural, and reconstruction studies have been added. These new studies were aimed at identifying immunohistochemically different subtypes of stem villi, their branching patterns, the distribution of macrophages, the stromal proliferation patterns, and the differentiation of extravascular stromal cells. Our findings demonstrate that the stem villi and their precursors, the immature intermediate villi, can selectively be identified by anti-gamma-smooth muscle (sm) actin staining. Furthermore, the existence of three different subtypes of stem villi is shown; these differ regarding the presence and distribution of gamma-sm actin-positive cells. These cells were immunohistochemically and ultrastructurally identified as smooth muscle cells and myofibroblasts. Increasingly complex coexpression patterns of cytoskeletal proteins reflect a clearly defined differentiation gradient of extravascular stromal cells, which covers the whole range of an undifferentiated germinative layer beneath the trophoblast to highly differentiated myofibroblasts surrounding the medias of the stem vessels. Possible functions of the extravascular contractile system include the regulation of villous turgor and the control of intervillous blood flow impedance.

PMID: 9260835