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On this website the Discussion Tab for a topic, or "talk pages", are used for several purposes: References - recent and historic that relates to the topic, Additional topic information - currently in draft format, Links - to related webpages, Topic page - an edit history as used on other Wiki sites, Lecture/Practical - student feedback, Student Projects - online project discussions.
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- Dr Mark Hill 2014, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G
Brain Museum - histology images from different species http://www.brainmuseum.org/Specimens/index.html
A Comparison of the Histological Structure of the Placenta in Experimental Animals
J Toxicol Pathol. 2014 Apr;27(1):11-18. Epub 2014 Apr 30.
Furukawa S1, Kuroda Y1, Sugiyama A2.
The primary function of the placenta is to act as an interface between the dam and fetus. The anatomic structure of the chorioallantoic placenta in eutherian mammals varies between different animal species. The placental types in eutherian mammals are classified from various standpoints based on the gross shape, the histological structure of the materno-fetal interface, the type of materno-fetal interdigitation, etc. Particularly, the histological structure is generally considered one of the most useful and instructive classifications for functionally describing placental type. In this system, three main types are recognized according to the cell layers comprising the interhemal area: (1) epitheliochorial type (horses, pigs and ruminants), (2) endotheliochorial type (carnivores) and (3) hemochorial type (primates, rodents and rabbits). The number of cell layers in the interhemal area is considered to modify the transfer of nutrients between maternal and fetal blood and is one of the important factors with respect to the difference in placental permeability between animal species. Therefore, in reproductive and developmental toxicity studies, careful attention should be paid to the histological structure of the interhemal area when extrapolating information concerning placental transfer characteristics to different animal species. KEYWORDS: cynomolgus monkey, dog, minipig, placenta, rabbit, rat
NOMINA ANATOMICA VETERINARIA http://www.wava-amav.org/Downloads/nav_2012.pdf
Standardised classification of pre-release development in male-brooding pipefish, seahorses, and seadragons (Family Syngnathidae)
BMC Dev Biol. 2012 Dec 29;12:39. doi: 10.1186/1471-213X-12-39.
Sommer S, Whittington CM, Wilson AB. Source Institute of Evolutionary Biology and Environmental Studies, University of Zürich, Winterthurerstrasse 190, Zürich, CH-8057, Switzerland. email@example.com. Abstract ABSTRACT: BACKGROUND: Members of the family Syngnathidae share a unique reproductive mode termed male pregnancy. Males carry eggs in specialised brooding structures for several weeks and release free-swimming offspring. Here we describe a systematic investigation of pre-release development in syngnathid fishes, reviewing available data for 17 species distributed across the family. This work is complemented by in-depth examinations of the straight-nosed pipefish Nerophis ophidion, the black-striped pipefish Syngnathus abaster, and the potbellied seahorse Hippocampus abdominalis. RESULTS: We propose a standardised classification of early syngnathid development that extends from the activation of the egg to the release of newborn. The classification consists of four developmental periods - early embryogenesis, eye development, snout formation, and juvenile - which are further divided into 11 stages. Stages are characterised by morphological traits that are easily visible in live and preserved specimens using incident-light microscopy. CONCLUSIONS: Our classification is derived from examinations of species representing the full range of brooding-structure complexity found in the Syngnathidae, including tail-brooding as well as trunk-brooding species, which represent independent evolutionary lineages. We chose conspicuous common traits as diagnostic features of stages to allow for rapid and consistent staging of embryos and larvae across the entire family. In view of the growing interest in the biology of the Syngnathidae, we believe that the classification proposed here will prove useful for a wide range of studies on the unique reproductive biology of these male-brooding fish.
Approaches and species in the history of vertebrate embryology
Methods Mol Biol. 2011;770:1-20.
Hopwood N. Source Department of History and Philosophy of Science, University of Cambridge, Cambridge, UK. firstname.lastname@example.org Abstract Recent debates about model organisms echo far into the past; taking a longer view adds perspective to present concerns. The major approaches in the history of research on vertebrate embryos have tended to exploit different species, though there are long-term continuities too. Early nineteenth-century embryologists worked on surrogates for humans and began to explore the range of vertebrate embryogenesis; late nineteenth-century Darwinists hunted exotic ontogenies; around 1900 experimentalists favored living embryos in which they could easily intervene; reproductive scientists tackled farm animals and human beings; after World War II developmental biologists increasingly engineered species for laboratory life; and proponents of evo-devo have recently challenged the resulting dominance of a few models. Decisions about species have depended on research questions, biological properties, supply lines, and, not least, on methods. Nor are species simply chosen; embryology has transformed them even as they have profoundly shaped the science.
Axolotl Development - (Ambystoma mexicanum) A salamander where the larvae do not undergo metamorphosis and adults remain gilled and aquatic. The ability to regenrate limbs has been used to study developmental pattern formation and nerve regeneration. Also used to investigate neural crest migration.
Obstetrics in elephants
Theriogenology. 2008 Jul 15;70(2):131-44. Epub 2008 May 21
Hermes R, Saragusty J, Schaftenaar W, Göritz F, Schmitt DL, Hildebrandt TB.
Leibniz Institute for Zoo and Wildlife Research, Berlin, Germany. email@example.com Abstract Obstetrics, one of the oldest fields in veterinary medicine, is well described and practiced in domestic and exotic animals. However, when providing care during elephant birth or dystocia, veterinary intervention options differ greatly from any domestic species, and are far more limited due to the dimensions and specific anatomy of the elephant reproductive tract. In addition, aging of captive elephant populations and advanced age of primiparous females make active birth management increasingly important. Intrauterine infection, uterine inertia and urogenital tract pathologies are emerging as major causes for dystocia, often leading to foetal and dam death. This paper reviews the current knowledge on elephant birth and the factors associated with dystocia. It then summarises recommendations for birth and dystocia management. As Caesarean section, the most common ultima ratio in domestic animal obstetrics, is lethal and therefore not an option in the elephant, non-invasive medical treatment, induction of the Fergusson reflex or the conscious decision to leave a retained foetus until it is expelled voluntarily, are key elements in elephant obstetrics. Surgical strategies such as episiotomy and foetotomy are sometimes inevitable in order to try to save the life of the dam, however, these interventions result in chronic post-surgical complications or even fatal outcome. Limited reliable data on serum calcium concentrations, and pharmacokinetics and effect of exogenous oestrogen, oxytocin, and prostaglandins during birth provide the scope of future research, necessary to advance scientific knowledge on obstetrics in elephants.
Foetal age determination and development in elephants
Hildebrandt T, Drews B, Gaeth AP, Goeritz F, Hermes R, Schmitt D, Gray C, Rich P, Streich WJ, Short RV, Renfree MB. Proc Biol Sci. 2007 Feb 7;274(1608):323-31.
Elephants have the longest pregnancy of all mammals, with an average gestation of around 660 days, so their embryonic and foetal development have always been of special interest. Hitherto, it has only been possible to estimate foetal ages from theoretical calculations based on foetal mass. The recent development of sophisticated ultrasound procedures for elephants has now made it possible to monitor the growth and development of foetuses of known gestational age conceived in captivity from natural matings or artificial insemination. We have studied the early stages of pregnancy in 10 captive Asian and 9 African elephants by transrectal ultrasound. Measurements of foetal crown-rump lengths have provided the first accurate growth curves, which differ significantly from the previous theoretical estimates based on the cube root of foetal mass. We have used these to age 22 African elephant foetuses collected during culling operations. Pregnancy can be first recognized ultrasonographically by day 50, the presumptive yolk sac by about day 75 and the zonary placenta by about day 85. The trunk is first recognizable by days 85-90 and is distinct by day 104, while the first heartbeats are evident from around day 80. By combining ultrasonography and morphology, we have been able to produce the first reliable criteria for estimating gestational age and ontological development of Asian and African elephant foetuses during the first third of gestation.
Grasshopper Development - A species used in neural development studies.
Embryonic development of the self-fertilizing mangrove killifish Kryptolebias marmoratus
Dev Dyn. 2011 Jul;240(7):1694-704. doi: 10.1002/dvdy.22668.
Mourabit S, Edenbrow M, Croft DP, Kudoh T. Source Biosciences, College of Life and Environmental Sciences, University of Exeter, Exeter, United Kingdom. Abstract The mangrove killifish, Kryptolebias marmoratus, is a self-fertilizing vertebrate offering vast potential as a model species in many biological disciplines. Previous studies have defined developmental stages but lacked visual representations of the various embryonic structures. We offer detailed photographic images of K. marmoratus development with revised descriptions. An improved dechorionation method was developed to provide high resolution photographs, in addition to a microinjection technique enabling cell marking in the yolk syncytial layer. Embryos were also treated with PTU (1-phenyl 2-thiourea), an inhibitor of melanogenesis, to provide optical transparency revealing internal structures in late stages of development. Chemical exposures (PTU and retinoic acid) demonstrated that K. marmoratus embryos were sensitive to chemicals, illustrating further their usefulness in developmental biology studies. Our data suggest that K. marmoratus embryos are easily used and manipulated, supporting the use of this hermaphroditic vertebrate as a strong comparative model system in embryology, evolution, genetics, environmental and medical biology.
Copyright © 2011 Wiley-Liss, Inc.
An embryonic staging table for in ovo development of Eublepharis macularius, the leopard gecko. Wise PA, Vickaryous MK, Russell AP. Anat Rec (Hoboken). 2009 Aug;292(8):1198-212. PMID: 19645023
Monkey Development - a model used for primate development studies.
Sea Urchin Development
Sea Urchin Development - A species used to study very early development from fertilization onward.