Pig Development

Introduction

Sow and piglet.

Pig (Sus scrofa) developmental model is studied extensively due to the commercial applications of pigs for meat production and for health issues such as obesity, cardiovascular disease, and organ transplantation (xenotransplantation).

Historically, there is an excellent description of the pig reproductive estrous cycle and the cyclic changes that occur within the ovary.

pig

Some Recent Findings

Historic drawing of early limb vasculature.

A gene expression atlas of the domestic pig "As an important livestock animal with a physiology that is more similar than mouse to man, we provide a major new resource for understanding gene expression with respect to the known physiology of mammalian tissues and cells. The data and analyses are available on the websites http://biogps.org and http://www.macrophages.com/pig-atlas." How pig sperm prepares to fertilize"We propose that this capacitation driven membrane docking and stability thereof is a preparative step prior to the multipoint membrane fusions characteristic for the acrosome reaction induced by sperm-zona binding." Axial differentiation and early gastrulation stages of the pig embryo "Differentiation of the principal body axes in the early vertebrate embryo is based on a specific blueprint of gene expression and a series of transient axial structures such as Hensen's node and the notochord of the late gastrulation phase. ... Intriguingly, the round shape and gradual posterior displacement of the APD in the pig appear to be species-specific (differing from all other mammals studied in detail to date) but correlate with ensuing specific primitive streak and extraembryonic mesoderm development. APD and, hence, the earliest axial structure presently known in the mammalian embryo may thus be functionally involved in shaping extraembryonic membranes and, possibly, the specific adult body form."

More recent papers

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Taxon

Taxonomy ID: 9823

Genbank common name: pig

Inherited blast name: even-toed ungulates

Rank: species

Genetic code: Translation table 1 (Standard)

Mitochondrial genetic code: Translation table 2 (Vertebrate Mitochondrial)

Other names: wild boar, swine, pigs

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; Cetartiodactyla; Suina; Suidae; Sus

Animal Models

Animal Model Comparison

Postnatal Animal Models	mouse	rat	pig
Pregnancy period (days)	18 – 21	21 – 23	110 – 118
Placenta type	Discoidal, decidual hemoendothelial choroidea	Discoidal, decidual hemoendothelial choroidea	Epitheliochorial
Litter size	6 – 12	6 – 15	11 – 16
Birth weight (g)	0.5 – 1.5	3 – 5	900 – 1600
Weaning weight male/female (g)	18 – 25/16 – 25	55 – 90/45 – 80	6000 – 8000
Suckling period (days)	21–28	21	28–49
Solid diet beginning (days)	10	12	12 – 15
Puberty male/female (week)	4 – 6/5	6/6 – 8	20 – 28
Life expectancy (years)	1 - 2	2 - 3	14 – 18
Table data - Otis and Brent (1954)   Links: timeline

Normal Stages

The images below are from the 1897 Normentafeln zur Entwicklungsgeschichte der Wirbeltiere - Sus scrofa domesticus (Normal Plates of the Development of the Pig Embryo) by Franz Keibel

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Uterus and Ovary

Diagram showing form and dimensions of the uterus and Fallopian tubes of the sow. Drawn from an average specimen taken from a young mature animal.

Estrous Cycle

Female pig is called a sow.

Non-Pregnant

Events of the average cycle of 21 days in the non-pregnant sow.

Diagram showing relationship between oestrua, ovulation, corpus luteum development, and the progress of the ova in the sow.

Pregnant

Events of the first weeks of pregnancy.

Diagram showing relationship between oestrua, ovulation, corpus luteum development, and the progress of the ova in the sow.

Scanning electron microscope images of the endometrial surface of a Day 13 pregnant sow.

Male Pig

Male pig is called a boar.

Capacitation alters the ultrastructure of the apical head and the acrosome of boar sperm.

Model for capacitation-induced stable docking of the acrosome to the sperm plasma membrane.

Pig Development

[[File:Keibel1897_plate01.jpg|thumb|400px|Images of pig development from 1897 book plate.

• The gestation period of a pig is 112 to 114 days.
• Female pigs can become pregnant at around 8 to 18 months of age.
• The pig has an estrus cycle occurring every 21 days if not bred.
• Male pigs become sexually active at 8 to 10 months of age.
• Embryos begin to attach to the uterus on days 13–14 of pregnancy.
• Day 15-20 implanted and expansion of allantois.
• A litter of piglets is between 6 and 12 piglets.

Data For Carnegie Stages Comparison Graph (Species/Days)

Species	Stage	9	10	11	12	13	14	15	16	17	18	19	20	21	22	23
Human	Days	20	22	24	28	30	33	36	40	42	44	48	52	54	55	58
Pig	Days	14	15	16	17	18	19	20.5	21.5	23	24	25.5	27.5	29	30.5	32.5

Links: Carnegie Stage Comparison

Neural Development

The data below is summarised from an excellent study of early neural development in the pig. The same authors have studied neural development in the rabbit.

• 7 somite embryo - first apposition of the neural folds occurs at somite levels 5-7. (corresponds to closure site I in mouse).
• next stage - rostral and caudal parts of the rhombencephalic folds appose, leaving an opening in between.
  • at this stage four neuropores can be distinguished, of which the anterior and posterior ones will remain open longest. (two rhombencephalic closure sites have no counterpart in the mouse, but do have some resemblance to those of the rabbit)

anterior neuropore

• closes in three phases

1. dorsal folds slowly align and then close instantaneously, the slow progression being likely due to a counteracting effect of the mesencephalic flexure
2. dorso-lateral folds close in a zipper-like fashion in caudo-rostral direction
3. final round aperture is likely to close by circumferential growth.

22 somite embryo - anterior neuropore is completely closed. (closure sites for the anterior neuropore in mouse embryo, none of these were detected in the pig embryo)

posterior neuropore

• closes initially very fast in the somitic region, but this process almost stops thereafter.
• stage 20-22 somites the posterior neuropore suddenly reduces in size but thereafter a small neuropore remains for 5 somite stages.
• closure of the posterior neuropore is completed at the stage of 28 somites.

8-20 somite embryos - the width of the posterior neuropore does not change, while the rate of closure gradually increases.

Additional Images

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  Arrangement of lymphatic vessels in 40 mm embryo

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  Lymphatic vessel network in embryo skin. A 18 mm; B 20 mm; C 30 mm; D 40 mm

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  Transverse section spinal cord 20 cm embryo

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  Wall of uterus and chorion

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  Transverse section of umbilical cord of a pig embryo six inches in length

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References

Recent References

Reviews

<pubmed></pubmed> <pubmed>22450280</pubmed> <pubmed>22127002</pubmed> <pubmed>21677026</pubmed> <pubmed></pubmed> <pubmed>770410</pubmed> <pubmed>4596894</pubmed> <pubmed>4973146</pubmed> <pubmed>4951167</pubmed>

Search PubMed

• pig development - All (22158) Review (1443) Free Full Text (6175)
• pig embryo - All (7265) Review (518) Free Full Text (1792)

Search Pubmed: pig development | pig embryo | Sus scrofa 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.

• NCBI - Pig Genome
• USA - PigBase a computer database that includes information on papers published about gene mapping in the pig.
• NSW Agriculture - Pig breeds and breeding
• AGBU - Pig Genetics

Glossary Links

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Cite this page: Hill, M.A. (2024, April 20) Embryology Pig Development. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Pig_Development

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