|A personal message from Dr Mark Hill (May 2020)
| I have decided to take early retirement in September 2020. During the many years online I have received wonderful feedback from many readers, researchers and students interested in human embryology. I especially thank my research collaborators and contributors to the site. The good news is Embryology will remain online and I will continue my association with UNSW Australia. I look forward to updating and including the many exciting new discoveries in Embryology!
The opossums are a family of nocturnal semi-arboreal marsupials including the cuscuses, brushtail possums, and their close relatives.
Some Recent Findings
- Sequence alteration in the enhancer contributes to the heterochronic Sox9 expression in marsupial cranial neural crest "Neonates of marsupial mammals are altricial at birth, because their gestation period is relatively short compared to placental mammals. Yet, as they need to travel to the teat from the birth canal, and suckle on the mother's milk, forelimbs and jaws develop significantly early. Previous studies in opossum (Monodelphis domestica), an experimental marsupial model, have revealed that cranial neural crest cells are generated significantly early compared to those in placental mammals, such as mouse, leading to an early development of jaw primordia. We have previously found that Sox9, an important neural crest-specifier gene, is expressed in the future cranial neural crest of the opossum embryonic ectoderm significantly earlier than that in mouse or quail embryos. As Sox9 is essential for neural crest formation in various vertebrates, it seems likely that the heterochronic expression of Sox9 is critical for the early cranial neural crest formation in the marsupial embryos. In this study, we show a marsupial-specific sequence in the Sox9 neural crest enhancer E3. We also reveal that the mouse E3 enhancer is activated in the cranial neural crest cells of quail embryos, that the E3 enhancer with marsupial-specific sequence is activated earlier in the Pax7-expressing neural border prior to the onset of endogenous Sox9 expression, and that a misexpression of cMyb, which is also a transcriptional activator of Pax7, in the neural border can ectopically activate the "marsupialized" enhancer. Thus, we suggest that the modification of the E3 enhancer sequence in the marsupial ancestor would have promoted the early expression of Sox9 in the neural border, facilitating the early formation of the cranial neural crest cells and the subsequent heterochronic development of the jaw primordia."
- Gene expression profiling of postnatal lung development in the marsupial gray short-tailed opossum (Monodelphis domestica) highlights conserved developmental pathways and specific characteristics during lung organogenesis "After a short gestation, marsupials give birth to immature neonates with lungs that are not fully developed and in early life the neonate partially relies on gas exchange through the skin. Therefore, significant lung development occurs after birth in marsupials in contrast to eutherian mammals such as humans and mice where lung development occurs predominantly in the embryo. To explore the mechanisms of marsupial lung development in comparison to eutherians, morphological and gene expression analysis were conducted in the gray short-tailed opossum (Monodelphis domestica)."
- Embryo implantation evolved from an ancestral inflammatory attachment reaction "The molecular changes that support implantation in eutherian mammals are necessary to establish pregnancy. In marsupials, pregnancy is relatively short, and although a placenta does form, it is present for only a few days before parturition. However, morphological changes in the uterus of marsupials at term mimic those that occur during implantation in humans and mice. We investigated the molecular similarity between term pregnancy in the marsupials and implantation in eutherian mammals using the gray short-tailed opossum (Monodelphis domestica) as a model. ...We demonstrate that key markers of implantation, including Heparin binding EGF-like growth factor and Mucin 1, exhibit expression and localization profiles consistent with the pattern observed during implantation in eutherian mammals. Finally, we show that there are transcriptome-wide similarities between the opossum attachment reaction and implantation in rabbits and humans. Our data suggest that the implantation reaction that occurs in eutherians is derived from an attachment reaction in the ancestral therian mammal which, in the opossum, leads directly to parturition. Finally, we argue that the ability to shift from an inflammatory attachment reaction to a noninflammatory period of pregnancy was a key innovation in eutherian mammals that allowed an extended period of intimate placentation." implantation
|More recent papers
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More? References | Discussion Page | Journal Searches | 2019 References | 2020 References
Search term: Opossum Embryology | Opossum Development
|These papers originally appeared in the Some Recent Findings table, but as that list grew in length have now been shuffled down to this collapsible table.
See also the Discussion Page for other references listed by year and References on this current page.
- On the prenatal initiation of T cell development in the opossum Monodelphis domestica "Thymus-dependent lymphocytes (T cells) are a critical cell lineage in the adaptive immune system of all jawed vertebrates. In eutherian mammals the initiation of T cell development takes place prenatally and the offspring of many species are born relatively immuno-competent. Marsupials, in contrast, are born in a comparatively altricial state and with a less well developed immune system. As such, marsupials are valuable models for studying the peri- and postnatal initiation of immune system development in mammals. Previous results supported a lack of prenatal T cell development in a variety of marsupial species. In the gray short-tailed opossum, Monodelphis domestica, however, there was evidence that αβT cells were present on postnatal day 1 and likely initiated development prenatally. Demonstrated here is the presence of CD3ε+ lymphocytes in late-stage embryos at a site in the upper thoracic cavity, the site of an early developing thymus. CD3ε+ cells were evident as early as 48 h prior to parturition. In day 14 embryos, where there is clear organogenesis, CD3ε+ cells were only found at the site of the early thymus, consistent with no extra-thymic sites of T cell development in the opossum. These observations are the first evidence of prenatal T cell lineage commitment in any marsupial." blood | thymus
- A new mammalian model system for thalidomide teratogenesis: Monodelphis domestica  "From 1957 to 1962, thalidomide caused birth defects in >10,000 children. While the drug was pulled from the market, thalidomide is currently prescribed to treat conditions including leprosy. As a result, a new generation of babies with thalidomide defects is being born in the developing world. This represents a serious problem, as the mechanisms by which thalidomide disrupts development remain unresolved. This lack of resolution is due, in part, to the absence of an appropriate mammalian model for thalidomide teratogenesis. We test the hypothesis that opossum (Monodelphis domestica) is well suited to model human thalidomide defects. Results suggest that opossum embryos exposed to thalidomide display a range of phenotypes (e.g., heart, craniofacial, limb defects) and penetrance similar to humans. Furthermore, all opossums with thalidomide defects exhibit vascular disruptions. Results therefore support the hypotheses that opossums make a good mammalian model for thalidomide teratogenesis, and that thalidomide can severely disrupt angiogenesis in mammals." thalidomide
- Comparative gene expression analyses reveal heterochrony for Sox9 expression in the cranial neural crest during marsupial development "Compared to placental mammals, marsupials have short gestation period, and their neonates are relatively immature. Despite these features, marsupial neonates must travel from the birth canal to the teat, suckle and digest milk to complete development. Thus, certain organs and tissues of marsupial neonates, such as forelimbs to crawl and jaw elements to suckle, must develop early. Previous reports showed that cranial neural crest (CNC) cells, as the source of ectomesenchyme of jaw elements, are generated significantly early in gray short-tailed opossum (Monodelphis domestica) compared to other amniote models, such as mouse. In this study, we examined the expression of genes known to be important for neural crest formation, such as BMP2/BMP4 (neural crest inducer), Pax7 (neural border specifier), Snail1 and Sox9/Sox10 (neural crest specifier) in Monodelphis domestica, and compared the expression patterns with those in mouse, chicken, and gecko embryos. Among those genes, the expression of Sox9 was turned on early and broadly in the premigratory CNC cells, and persisted in the ectomesenchyme of the cranial anlagen in opossum embryos. In contrast, Sox9 expression diminished in the CNC cells of other animals at the early phase of migration. Comparison of the onset of Pax7 and Sox9 expression revealed that Sox9 expression in the prospective CNC was earlier and broader than Pax7 expression in opossum, suggesting that the sequence of border specification and neural crest specification is altered."
- Developmental origins of precocial forelimbs in marsupial neonates "Marsupial mammals are born in an embryonic state, as compared with their eutherian counterparts, yet certain features are accelerated. The most conspicuous of these features are the precocial forelimbs, which the newborns use to climb unaided from the opening of the birth canal to the teat. The developmental mechanisms that produce this acceleration are unknown. Here we show that heterochronic and heterotopic changes early in limb development contribute to forelimb acceleration. Using Tbx5 and Tbx4 as fore- and hindlimb field markers, respectively, we have found that, compared with mouse, both limb fields arise notably early during opossum development."
Phylogenetic tree of marsupialsNilsson MA, Churakov G, Sommer M, Tran NV, Zemann A, Brosius J & Schmitz J. (2010). Tracking marsupial evolution using archaic genomic retroposon insertions. PLoS Biol. , 8
, e1000436. PMID: 20668664 DOI
Genbank common name: opossum
Genetic code: Translation table 1 (Standard)
Mitochondrial genetic code: Translation table 2 (Vertebrate Mitochondrial)
Lineage ( full )
- Links: Taxonomy Browser Phalangeridae
|Marsupial - Opossum Taxon List
||Chacoan pygmy opossum
||northern gracile opossum
||Junin slender opossum
||Ojasti's slender mouse opossum
||spectacled slender opossum
||Voss' slender opossum
||Bishop's slender opossum
||dusky slender opossum
||Guahiba gracile opossum
||hooded red-sided opossum
||Gardner's short-tailed opossum
||northern shew opossum
||Sangay shrew opossum
||Brazilian slender opossum
||Andean white-eared opossum
||Derby's woolly opossum
||Red three-striped opossum
||Long-nosed short-tailed opossum
||Southern red-sided opossum
||Amazonian red-sided opossum
||Tate's fat-tailed mouse opossum
||Argentine fat-tailed mouse opossum
||White-bellied woolly mouse opossum
||Tyleria mouse opossum
||Guajira mouse opossum
||Northern three-striped opossum
||Mountain brushtail opossum
||Ihering's three-striped opossum
||grey-bellied shrew opossum
||Panama slendeer opossum
||Guianan white-eared opossum
||Dwarf fat-tailed mouse opossum
||Handley's slender mouse opossum
||Osgood's short-tailed opossum
||Aceramarca gracile mouse opossum
||Emilia's gracile mouse opossum
||Cinderella fat-tailed opossum
||Tate's wolly mouse opossum
||grayish mouse opossum
||Southeastern four-eyed oppossum
||gray slender mouse opossum
||Theresa's short-tailed opossum
||Mexican mouse opossum
||Anderson's mouse opossum
||Pygmy short-tailed Opossum
||Red-legged short-tailed Opossum
||Common fat-tailed mouse opossum
||long-tailed fat-tailed opossum
||elegant fat-tailed opossum
||Agile Gracile Mouse Opossum
||pallid fat-tailed opossum
||Emilia's short-tailed opossum
||delicate slender mouse opossum
||white-bellied slender mouse opossum
||murine mouse opossum
||little rufous mouse opossum
||Brazilian gracile mouse opossum
||Dorothy's slender mouse opossum
||Robinson's mouse opossum
||bare-tailed woolly opossum
||Incan shrew opossum
||sepia short-tailed opossum
||brown four-eyed opossum
||Andean slender mouse opossum
||Short-furred woolly mouse opossum
||long-furred woolly mouse opossum
||red mouse opossum
||western woolly opossum
||silky shrew opossum
||Chilean shrew opossum
||gray short-tailed opossum
||gray four-eyed opossum
||North American opossum
Opossum and day 7 pups
The marsupial neonate at birth has a variation between the degree of development of different systems.
- well-developed - digestive, respiratory and circulatory system.
- not well-developed - retains fetal excretory system with a fully functional mesonephric kidney and undifferentiated gonads and genitalia.
Ovarian Follicle Development
Marsupial eggs are enclosed by a series of layers:
- zona pellucida, three zona proteins (ZPA, ZPB, ZPC)
- an additional extracellular matrix coat that lines the zona pellucida also occurs in some species.
- mucoid coat
- outer shell coat.
- Links: oocyte
- Links: spermatozoa
- ↑ 1.0 1.1 Wheaton BJ, Callaway JK, Ek CJ, Dziegielewska KM & Saunders NR. (2011). Spontaneous development of full weight-supported stepping after complete spinal cord transection in the neonatal opossum, Monodelphis domestica. PLoS ONE , 6, e26826. PMID: 22073202 DOI.
- ↑ Wakamatsu Y & Suzuki K. (2019). Sequence alteration in the enhancer contributes to the heterochronic Sox9 expression in marsupial cranial neural crest. Dev. Biol. , 456, 31-39. PMID: 31430446 DOI.
- ↑ Modepalli V, Kumar A, Sharp JA, Saunders NR, Nicholas KR & Lefèvre C. (2018). Gene expression profiling of postnatal lung development in the marsupial gray short-tailed opossum (Monodelphis domestica) highlights conserved developmental pathways and specific characteristics during lung organogenesis. BMC Genomics , 19, 732. PMID: 30290757 DOI.
- ↑ Griffith OW, Chavan AR, Protopapas S, Maziarz J, Romero R & Wagner GP. (2017). Embryo implantation evolved from an ancestral inflammatory attachment reaction. Proc. Natl. Acad. Sci. U.S.A. , 114, E6566-E6575. PMID: 28747528 DOI.
- ↑ Hansen VL & Miller RD. (2017). On the prenatal initiation of T cell development in the opossum Monodelphis domestica. J. Anat. , 230, 596-600. PMID: 28052333 DOI.
- ↑ Sorensen D, Sackett A, Urban DJ, Maier J, Vargesson N & Sears KE. (2017). A new mammalian model system for thalidomide teratogenesis: Monodelphis domestica. Reprod. Toxicol. , 70, 126-132. PMID: 28130151 DOI.
- ↑ Wakamatsu Y, Nomura T, Osumi N & Suzuki K. (2014). Comparative gene expression analyses reveal heterochrony for Sox9 expression in the cranial neural crest during marsupial development. Evol. Dev. , 16, 197-206. PMID: 24934187 DOI.
- ↑ Keyte AL & Smith KK. (2010). Developmental origins of precocial forelimbs in marsupial neonates. Development , 137, 4283-94. PMID: 21098569 DOI.
- ↑ Renfree MB, Pask AJ & Shaw G. (2001). Sex down under: the differentiation of sexual dimorphisms during marsupial development. Reprod. Fertil. Dev. , 13, 679-90. PMID: 11999321
- ↑ Selwood L. (2000). Marsupial egg and embryo coats. Cells Tissues Organs (Print) , 166, 208-19. PMID: 10729728 DOI.
Search PubMed: Dromiciops gliroides | Opossum development | marsupial development
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Cite this page: Hill, M.A. (2020, July 3) Embryology Opossum Development. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Opossum_Development
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