Horse Development

Embryology - 18 Apr 2024 Expand to Translate
Google Translate - select your language from the list shown below (this will open a new external page)
العربية \| català \| 中文 \| 中國傳統的 \| français \| Deutsche \| עִברִית \| हिंदी \| bahasa Indonesia \| italiano \| 日本語 \| 한국어 \| မြန်မာ \| Pilipino \| Polskie \| português \| ਪੰਜਾਬੀ ਦੇ \| Română \| русский \| Español \| Swahili \| Svensk \| ไทย \| Türkçe \| اردو \| ייִדיש \| Tiếng Việt These external translations are automated and may not be accurate. (More? About Translations)

Introduction

Equine development (Latin, equus = "horse")

Horse Links: horse | Category:Horse

Historic Papers: 1897 Critical Period in Horse Development | 1925 Organ of Jacobson | 1945 Cleavage Stages of the Horse Ova

Historic Embryology
1897 Pig \| 1900 Chicken \| 1901 Lungfish \| 1904 Sand Lizard \| 1905 Rabbit \| 1906 Deer \| 1907 Tarsiers \| 1908 Human \| 1909 Northern Lapwing \| 1909 South American and African Lungfish \| 1910 Salamander \| 1951 Frog \| Embryology History \| Historic Disclaimer

Some Recent Findings

Random X inactivation in the mule and horse placenta^[1] "In eutherian mammals, dosage compensation of X-linked genes is achieved by X chromosome inactivation. X inactivation is random in embryonic and adult tissues, but imprinted X inactivation (paternal X silencing) has been identified in the extra-embryonic membranes of the mouse, rat, and cow. ...As the most structurally and morphologically diverse organ in mammals, the placenta also appears to show diverse mechanisms for dosage compensation that may result in differences in conceptus development across species."

More recent papers
This table allows an automated computer search of the external PubMed database using the listed "Search term" text link. This search now requires a manual link as the original PubMed extension has been disabled. The displayed list of references do not reflect any editorial selection of material based on content or relevance. References also appear on this list based upon the date of the actual page viewing. References listed on the rest of the content page and the associated discussion page (listed under the publication year sub-headings) do include some editorial selection based upon both relevance and availability. More? References \| Discussion Page \| Journal Searches \| 2019 References \| 2020 References Search term: Equine Embryology <pubmed limit=5>Equine Embryology</pubmed>

Taxon

Equine Development

338 days

Animal Development Time

Animal	Average Days
Bear (Black)	210
Bison	270
Budgerigar	18
Camel	410
cat	65
cow	281
chicken	21
Chimpanzee	236
Chinchilla	111
Coyote	63
deer (Mule)	200
dog	63
Donkey	365
Duck	28
Duck (Muscovy)	35
elephant	660
Elk, Wapiti	255
Ferret	42
Finch	14
Fox	52
Giraffe	425
goat	150
Goose	28
Gorilla	270
Guinea fowl	28
guinea pig	68
Hare	36
Hippopotamus	240
horse	338
Human	274
Leopard	95
Lion	108
Llama	350
Marmoset	150
Mink (European)	41
monkey (Macaque)	180
Moose	240
mouse	20
Muskox	255
Muskrat	29
Nutria, Coypu	130
opossum	12
Otter	285
Panther	90
Parrot	26
Pheasant	24
Pig	114
Pigeon	18
Porcupine	210
Pronghorn	230
Quail	16
rabbit	31
Raccoon	63
rat	21
Reindeer	225
Rhinoceros (African)	480
Seal	330
sheep	150
Shrew	20
Skunk	63
Squirrel (Gray)	40
Swan	35
Tapir	390
Tarsier	182
Tiger	103
Turkey	28
Walrus	450
whale (Sperm)	450
Wolf	63
Woodchuck	31

Animal Notes and Table Data Sources

Each animal species has different variations +/- the average values shown in the table.
Gestation is the carrying of an animal embryo or fetus inside a female viviparous animal. Except in the case of human gestational age GA.
Incubation is the laying of an egg (birds, reptiles, monotremes) with development occurring outside the female animal.

Genetics

Chromosomes: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 |

31 | X | 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 X

Genome: Equus caballus

Morula and Blastocyst

The following images are from a historic (1945) article on early horse development.^[2]

Links: Fig. 1 | Fig. 2 | Fig. 3 | Fig. 4 | Fig. 5 | Plate 1 | Fig 6 | Fig 7 | Fig 8 | Fig 9 | Fig 10 | Fig 11 | Plate 2 | Fig 12 | Fig 13 | Fig 14 | Fig 15 | Plate 3

Historic Disclaimer - information about historic embryology pages
Pages where the terms "Historic" (textbooks, papers, people, recommendations) appear on this site, and sections within pages where this disclaimer appears, indicate that the content and scientific understanding are specific to the time of publication. This means that while some scientific descriptions are still accurate, the terminology and interpretation of the developmental mechanisms reflect the understanding at the time of original publication and those of the preceding periods, these terms, interpretations and recommendations may not reflect our current scientific understanding. (More? Embryology History \| Historic Embryology Papers)

Plate 1

Fig. 1. Photograph of a living unsegmented ovum of the pony (P 1) in Locke’s fluid. Granular material is seen in the perivitelline space. X 480.
Fig. 2: Photograph of an unsegmented ovum of the pony (P 1) in agar. The nucleus is just visible. x 480.
Fig. 3. Section of an unsegmented ovum of the pony (P1) with a large vesicular nucleus. x 520.
Fig. 4. Section of an unsegmented ovum of the pony (P 8) showing deutoplasmolysis. x 520.
Fig. 5. Photograph of a living two-cell stage ovum of the pony (P 5). Granular material is seen in the lower part of the perivitelline space. x 480.

Plate 2

Figs. 6, 7. Two consecutive sections through the two-cell ovum shown in fig. 5. x 520.
Figs. 6, 7. Two consecutive sections through the two-cell ovum shown in fig. 5. x 520.
Fig. 8. Photograph of a living four-cell stage ovum of the pony (P 7). x 480.
Figs. 9, 10. Two consecutive sections through the four-cell ovum shown in fig. 8. x 520.
Figs. 9, 10. Two consecutive sections through the four-cell ovum shown in fig. 8. x 520.
Fig. 11. Photograph of a five-cell stage ovum of the pony (P 4) in agar. x 480.

Plate 3

Fig. 12. Section through the five-cell ovum shown in fig. 11. x 520.
Fig. 13. Photograph of the living morula. of the pony (P 6). it shows extensive deutoplasmolysis. x 480.
Figs. 14, 15. Two consecutive sections through the morula. shown in fig. 13. x 520.
Figs. 14, 15. Two consecutive sections through the morula. shown in fig. 13. x 520.

Genital Development

Gastrointestinal Tract

Prenatal Development of the Digestive System in the Horse.^[3]

21 days - oral cavity was an empty space, and the liver contained proliferating endodermal cells.
25 days - fusiform stomach and the pancreatic bud were present.
28 days - small tongue and the esophagus occurred.
30 days - primary and secondary palates were developed, the liver contained cords of hepatocytes, and the pancreas was triangular.
40 days - crypts had formed in the intestinal loops, cell differentiation was observed in the hepatic parenchyma, and the pancreas was elongated.
50 days - Pancreatic acini and islets and intestines were highly convoluted.
75 days - Three segments of the pharynx
105 days - intestinal villi were wide with round tips; especially, the liver, stomach, and oral cavity showed key steps of anatomical and cellular differentiation.

References

↑ <pubmed>22645258</pubmed>
↑ Hamilton WJ. Cleavage Stages of the Ova of the Horse, with Notes on Ovulation. J Anat. 1945 Jul; 79(Pt 3): 127–130.3.
↑ <pubmed>24778084</pubmed>

Reviews

Articles

Search Pubmed

Search Pubmed: equine development

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.

Oklahoma State University Learning Reproduction in Farm Animals

Historic Embryology
1897 Pig \| 1900 Chicken \| 1901 Lungfish \| 1904 Sand Lizard \| 1905 Rabbit \| 1906 Deer \| 1907 Tarsiers \| 1908 Human \| 1909 Northern Lapwing \| 1909 South American and African Lungfish \| 1910 Salamander \| 1951 Frog \| Embryology History \| Historic Disclaimer

Glossary Links

Glossary: A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z | Numbers | Symbols | Term Link

Cite this page: Hill, M.A. (2024, April 18) Embryology Horse Development. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Horse_Development

What Links Here?

[PMID22645258-1] <pubmed>22645258</pubmed>

[2] Hamilton WJ. Cleavage Stages of the Ova of the Horse, with Notes on Ovulation. J Anat. 1945 Jul; 79(Pt 3): 127–130.3.

[3] <pubmed>24778084</pubmed>

[1]

[2]

[3]