Dog Development: Difference between revisions

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==Placenta==
==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)
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)
# 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.
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)
(Data from: Miglino MA, etal., 2006<ref><pubmed>16563485</pubmed></ref> and other sources)





Revision as of 08:45, 5 April 2012

Introduction

Adult dog
Canine oocyte
Canine Embryo (E35-38)
Dog breeds[1]

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.


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| Dog Development - Abnormalities

Some Recent Findings

  • Embryo biotechnology in the dog: a review[3] "Canine embryos are a scarce biological material because of difficulties in collecting in vivo-produced embryos and the inability, to date, to produce canine embryos in vitro. The procedure for the transfer of in vivo-produced embryos has not been developed adequately, with only six attempts reported in the literature that have resulted in the birth of 45 puppies. In vitro, the fertilisation rate is particularly low ( approximately 10%) and the incidence of polyspermy particularly high. So far, no puppy has been obtained from an in vitro-produced embryo. In contrast, cloning of somatic cells has been used successfully over the past 4 years, with the birth of 41 puppies reported in the literature, a yield that is comparable to that for other mammalian species. Over the same period, canine embryonic stem sells and transgenic cloned dogs have been obtained."
  • Cryopreservation of Canine Embryos[4] "Canine embryos were collected from excised reproductive organs after artificial insemination and subsequently cryopreserved by a vitrification method. When the 4-cell to morula stage of cryopreserved embryos were non-surgically transferred into the uteri of nine recipient bitches by using a cystoscope, five recipients became pregnant and four of them delivered a total of seven pups."
  • Prolonged duration of fertility of dog ova [5] "The fertile period for natural mating in dogs extends from before ovulation until day 5 post ovulation (PO) and involves a delay in oocyte maturation until 2-3 days PO and viability of secondary oocytes for 48-60 h or more. Spermatozoa do not enter the uterus after vaginal insemination in late oestrus. Cervical closure appears to occur on average 5 days PO, but conception may occur following intrauterine artificial insemination (IUAI) up to 8 days PO. Therefore, the present study was conducted to clarify the duration of fertility of canine ova. Using IUAI at 6, 7, 8 and 9 days PO (n = 5 bitches each) conception rates were 100%, 71.4%, 37.5% and 0%, respectively, with an average litter resorption rate of 30.8%, and with mean litter sizes and times to delivery PO being 4.3 +/- 1.6 and 64.3 +/- 0.3 days, 4.0 +/- 1.4 and 66.3 +/- 0.4 days, and 2.5 and 68 days for IUAI at 6, 7 and 8 days, respectively. The high pregnancy rates with IUAI at 6 and 7 days PO confirm that many canine oocytes are fertile at 4-5 days after maturation. The high rate of resorption was presumably because of aging of ova or asynchrony between embryonic development and the intrauterine environment."
Links: References | Recent References

Taxon

Dog genetics[1]
Alan Wilton (1953–2011)

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

Dog genome.jpg


Links: Dog Genome Map View | NHGRI Dog Genome Project

Oocyte Development

Transmission electron micrographs of canine geminal vesicle (GV) oocytes.[6]

Canine oocyte 04.jpg

Canine geminal vesicle (GV) oocyte.[6]

Canine oocyte 02.jpg

Dog oocyte development. (A) GV (B) GVBD (C) MI and (D) MII[6]

Oocyte to Blastocyst

Canine oocyte to blastocyst.jpg

Canine oocyte to blastocyst (Image: Dr Karine Reynaud).

Development Overview

Dog embryo at neural fold stage of development

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[7]
  • 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)

See also Concannon 2001


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).

Carnegie Stages

Canine embryo at day 40 after mating, this corresponds approximately to ~day 35-38 after fertilisation (Image: Dr Karine Reynaud).

Gestational age timed from day 0 as the day of the preovulatory serum progesterone rise in the dam, should roughly correlate with fertilisation (+/- 1 day), data[8] *calculated staging only available.

  • day 27 - carnegie stage 13.5
  • day 28* - carnegie stage 14-15
  • day 29* - carnegie stage 15-16
  • day 30 - carnegie stage 17
  • day 34 - carnegie stage 18.5 – 19
  • day 36 - carnegie stage 19.5–20
  • day 37 - carnegie stage 20


Links: Carnegie Stages


Historic Embryology

These images are from drawings by Charles Bonnet (1909), later republished in a 1921 textbook of embryology.[9]

Links: Carnegie Stage Comparison
Alaskan sled dogs, bred for their racing performance.[10]

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[11]
    • 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:

  1. girdle zone (endotheliochorial labyrinth)
  2. hemochorial hemophagous zone (marginal hematoma)
  3. 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[12] and other sources)


Links: Comparative Placentation - Dog

Urogenital System

Dog- male urogenital cartoon.jpg Dog- female urogenital cartoon.jpg
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.[13]

Genital Ridge Sry and Sox9[14]

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[15]

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

Spermatogenesis

The cartoons below show nanog expression in the dog during spermatogenesis.[16]

Dog- spermatozoa NANOG expression.jpg Each column represents the combination of different cell types that are present in seminiferous tubules at that specific stage.

Cell types that express NANOG are outlined in red and cell types that do not express NANOG have black and grey symbols.

Legend

  • 1–16 = steps in spermiogenesis
  • In = intermediate spermatogonia
  • B = type B spermatogonia
  • Pl = pre-leptotene stage
  • L = leptotene stage
  • Z = zygotene stage
  • P = pachytene stage
  • D = diplotene stage
  • 2nd = generation of secondary spermatocytes
  • Roman figures = stage of the epithelial cycle

Puberty

Sexual Development Phases in Female of Laboratory Species[17]
Phase Rat Dog (beagle) Primate (monkey)
Neonatal Birth to postnatal Day 7 Birth–3 weeks Birth to 3–4 months
Infantile Postnatal Days 8–21 3–5 weeks Up to 29 months
Juvenile/prepubertal Postnatal Days 22–37 5 weeks–6 months Up to 43 months
Pubertal Postnatal Days 37–38 6–8 months 27–30 months

Hair Development

Coat variation in the domestic dog is governed by variants in three genes.[18]

"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."

Stem Cells

In 2009 a range of canine embryonic stem cell (ESC) lines were developed from preimplantation-stage embryos.[19]

  • maintained a normal karyotype and morphology typical of undifferentiated ESCs after multiple in vitro passages and cryopreservation.
  • embryoid bodies formed in the absence of a feeder layer in attachment or suspension culture.
  • embryoid bodies differentiated into multiple cell types.
  • ESCs introduced in vivo formed teratomas containing cell types of all three embryonic germ layers.

Abnormalities

Newborn bulldog with cleft palate.

There are a number of dog developmental abnormalities that are used as models for human disease.

There are currently 566 abnormality links listed on the Online Mendelian Inheritance in Animals database.


Search OMIA: Canis familiaris

Genital

  • Intersex
  • Sex reversal - not due to SRY gene translocation to an X chromosome.

Cardiac Defects

  • Canine-dilated cardiomyopathy - not associated with canine desmin.[20]

Hip dysplasia

British Veterinary Association and the German Shepherd League scoring scheme

  • scoring of nine different radiographic features of each hip
  • scale from 0 (ideal) to 6 (worst)
  • potential range of subjective scores from 0 to 108.


Links: Dog Development - Abnormalities | OMIA - Hip dysplasia

Other

  • 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.


Links: OMIA 566 abnormality links | Online Mendelian Inheritance in Animals

References

  1. 1.0 1.1 <pubmed>16311623</pubmed>| PLoS
  2. <pubmed>16341006</pubmed>
  3. <pubmed>20797342</pubmed>
  4. <pubmed>20926804</pubmed>
  5. <pubmed>19754575</pubmed>
  6. 6.0 6.1 6.2 <pubmed>20565987</pubmed>| Reprod Biol Endocrinol.
  7. <pubmed>12620580</pubmed>
  8. <pubmed>12840810</pubmed>
  9. Bailey, F.R. and Miller, A.M. (1921). Text-Book of Embryology. New York: William Wood and Co. online edition
  10. <pubmed>20649949</pubmed>| BMC Genet.
  11. <pubmed>17212978</pubmed>
  12. <pubmed>16563485</pubmed>
  13. <pubmed>1751638</pubmed>
  14. <pubmed>12840810</pubmed>
  15. <pubmed>15685633</pubmed>
  16. <pubmed>20539761</pubmed>| PLoS One.
  17. <pubmed>12866705</pubmed>
  18. <pubmed>19713490</pubmed>
  19. <pubmed>19038794</pubmed>
  20. <pubmed>15475165</pubmed>


Reviews

<pubmed>20797342</pubmed> <pubmed>20537823</pubmed> <pubmed>19942060</pubmed> <pubmed>17560591</pubmed> <pubmed>16564415</pubmed>

Articles

<pubmed>20477984</pubmed> <pubmed>19059739</pubmed> <pubmed>17212978</pubmed> <pubmed>17560591</pubmed> <pubmed>16869883</pubmed> <pubmed>4641196</pubmed> <pubmed>5165787</pubmed> <pubmed>7462099</pubmed>

Online Textbooks

Books

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.



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Historic Embryology  
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Cite this page: Hill, M.A. (2024, March 29) Embryology Dog Development. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Dog_Development

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© Dr Mark Hill 2024, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G