Dog Development: Difference between revisions
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* 22 to 23 days - heartbeat visible | * 22 to 23 days - heartbeat visible | ||
* 62 to 64 days - parturition (birth or whelping) | * 62 to 64 days - parturition (birth or whelping) | ||
Sexual differentiation begins early in the embryonic period prenatally and continues into early postnatal life. | Sexual differentiation begins early in the embryonic period prenatally and continues into early postnatal life. |
Revision as of 01:35, 16 December 2010
Introduction
The domestic dog (Canis lupus familiaris) has been derived from an ancestoral wolf and now consists of a breed family of more than 300 worldwide, with extensive variations in morphology (size, shape and weight). The modern dog breeds show high phenotypic diversity and are thought to have arisen from this first population bottleneck associated with wolf domestication (7,000–50,000 generations ago) and a second from more recent intensive selection to create the breed (50–100 generations ago).[2]
The average canine gestation period from ovulation to birth (parturition) is approximately 64 days and there have been identified about 400 congenital disorders relating to dog development. Many of these developmental abnormalities are common to human development.
Animal Development: axolotl | bat | cat | chicken | cow | dog | dolphin | echidna | fly | frog | goat | grasshopper | guinea pig | hamster | horse | kangaroo | koala | lizard | medaka | mouse | opossum | pig | platypus | rabbit | rat | salamander | sea squirt | sea urchin | sheep | worm | zebrafish | life cycles | development timetable | development models | K12 |
Some Recent Findings
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Taxon
NCBI Taxonomy Browser Canis lupus familiaris (Genbank common name: dog)
Synonyms: Canis familiaris, Canis domesticus, Canis canis
Chromosomes: 40 (38, X, Y)
Genetic code: Translation table 1 (Standard)
Mitochondrial genetic code: Translation table 2 (Vertebrate Mitochondrial) 16,700 bp
Lineage( full ):cellular organisms; Eukaryota; Fungi/Metazoa group; Metazoa; Eumetazoa; Bilateria; Coelomata; Deuterostomia; Chordata; Craniata; Vertebrata; Gnathostomata; Teleostomi; Euteleostomi; Sarcopterygii; Tetrapoda; Amniota; Mammalia; Theria; Eutheria; Laurasiatheria; Carnivora; Caniformia; Canidae; Canis; Canis lupus
Development Overview
Days shown below relate to days after ovulation (day 0).
- 48-72 h - oocytes need to complete post-ovulatory maturation to the metaphase II stage in the isthmus of the oviduct[5]
- 2 to 5 days - fertilization
- 14 to 16 days - embryo attaches to uterus
- 22 to 23 days - heartbeat visible
- 62 to 64 days - parturition (birth or whelping)
Sexual differentiation begins early in the embryonic period prenatally and continues into early postnatal life.
Caudal vena cava development- five theories to origin (right-sided supracardinal, caudal cardinal, sacrocardinal, lateral sympathetic or subcardinal veins).
Estrous Cycle
Estrus, also called "in heat" is the time of sexually receptivity and occurs every 17 to 21 days.
- Ovulation occurs 5 to 6 days prior to the first day of diestrus and is indicated by plasma progesterone concentrations higher than 2 ng/mL. (Parturition (birth or whelping) occurs between 62 to 64 days after ovulation).
- Ovulated oocytes diameter[7]
- with the zona pellucida (167.5+/-12.7 microns)
- without zona pellucida (133.9+/-5.3 microns)
- Links: Estrous Cycle
Placenta
Classified as endotheliochorial placentation forming a zonary placenta, which is a complete girdle in dogs. Three zones: girdle zone (endotheliochorial labyrinth), hemochorial hemophagous zone (marginal hematoma) and polar zone (epitheliochorial free)
Trophoblast cell invasion continues after chorioallantois villous penetration and the materno–fetal interface is described as lamellar, with fetal projections interdigitating with maternal septa.
(Data from: Miglino MA, etal., 2006 and other sources)
Urogenital System
Male Urogenital | Female Urogenital |
Male Gonad
Male sex differentiation is initially mediated by Sry expression then Leydig cell produced testosterone and anti-mullerian hormone (AMH, Mis), also called mullerian-inhibiting substance (MIS) or factor (MIF).
A study using timed pregnancies and male embryo development identified testis differentiation at 36 days gestation. At this time Mullerian duct regression also commenced and was completed by 46 days gestation. Immunohistochemistry also identified Mullerian Inhibitory Substance (MIS) was present during this period in testes and was absent in the undifferentiated testis.[8]
Genital Ridge Sry and Sox9[9]
Testis induction is associated with gonadal Sry and Sox9 expression in mammals, and also with Sox9 expression in vertebrates where Sry is absent. Timing was based upon the equivalent human carnegie staging and expression was measured by quantitative reverse transcription-polymerase chain reaction (qRT-PCR).
- Carnegie Stage 16-18 - Sry expression rose in genital ridge continuously, Sox9 expressed in both male and female genital ridge
- Carnegie Stage 17 - Sox9 expression tenfold greater than in the ovary
- Carnegie Stage 18 - Sry expression maximal
Chromosome 9 Sox 9
Genital Ridge Sf1 and Mis[10]
Mullerian-inhibiting substance - (Mis, Mif) Anti-mullerian hormone (AMH)
Splicing factor 1 - (Sf1) 623 amino acid protein containing a nuclear transport domain, a metal-binding or zinc finger motif, and glutamine- and proline-rich regions.
- Carnegie Stage 15 - Sf1 expression begins in genital ridges
- Carnegie Stage 17 - Sf1 expression pronounced in male and female gonads
- Carnegie Stage 18 - Mis expression only in male gonads
Chromosome 20 Anti-Mullerian hormone
- Links: Sry | Sox9 | Sox 9 Gene | Sf1 | Mis
Hair Development
Coat variation in the domestic dog is governed by variants in three genes.[11]
- "Coat color and type are essential characteristics of domestic dog breeds. Although the genetic basis of coat color has been well characterized, relatively little is known about the genes influencing coat growth pattern, length, and curl. We performed genome-wide association studies of more than 1000 dogs from 80 domestic breeds to identify genes associated with canine fur phenotypes. Taking advantage of both inter- and intrabreed variability, we identified distinct mutations in three genes, RSPO2, FGF5, and KRT71 (encoding R-spondin-2, fibroblast growth factor-5, and keratin-71, respectively), that together account for most coat phenotypes in purebred dogs in the United States. Thus, an array of varied and seemingly complex phenotypes can be reduced to the combinatorial effects of only a few genes."
Abnormalities
There are a number of dog developmental abnormalities that are used as models for human disease. A comprehensive list of dog related genetic abnormalities can be found at Online Mendelian Inheritance in Animals
- Sex reversal XX male - not due to SRY gene translocation to an X chromosome.
- Cardiac Defects
- Canine-dilated cardiomyopathy - not associated with canine desmin.[12]
- Hip dysplasia
- Congenital renal disease
- Canine Eclampsia - (puerperal tetany, hypocalcemia) develops mainly in small-breed dogs with large litters.
- Brucellosis - male and female can be carriers of this sexually transmitted disease.
References
- ↑ 1.0 1.1 <pubmed>16311623</pubmed>| PLoS
- ↑ <pubmed>16341006</pubmed>
- ↑ <pubmed>20926804</pubmed>
- ↑ <pubmed>19754575</pubmed>
- ↑ <pubmed>12620580</pubmed>
- ↑ <pubmed>20649949</pubmed>| BMC Genet.
- ↑ <pubmed>17212978</pubmed>
- ↑ <pubmed>1751638</pubmed>
- ↑ <pubmed>12840810</pubmed>
- ↑ <pubmed>15685633</pubmed>
- ↑ <pubmed>19713490</pubmed>
- ↑ <pubmed>15475165</pubmed>
Reviews
Articles
<pubmed>20477984</pubmed> <pubmed>19059739</pubmed> <pubmed>17212978</pubmed> <pubmed>17560591</pubmed> <pubmed>16869883</pubmed> <pubmed>4641196</pubmed> <pubmed>5165787</pubmed>
Books
- Complete Book of Dog Breeding by DVM Dan Rice
- Practical Dog Breeding: Principles and Practice by William Haynes (1915)
Search Pubmed
Search Pubmed Now: dog development | canine development | Estrous Cycle |
External Links
External Links Notice - The dynamic nature of the internet may mean that some of these listed links may no longer function. If the link no longer works search the web with the link text or name. Links to any external commercial sites are provided for information purposes only and should never be considered an endorsement. UNSW Embryology is provided as an educational resource with no clinical information or commercial affiliation.
- University of Georgia College of Veterinary Medicine The Canine Estrous Cycle
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Cite this page: Hill, M.A. (2024, June 15) Embryology Dog Development. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Dog_Development
- © Dr Mark Hill 2024, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G