Pig Development

Embryology - 2 Dec 2023        Expand to Translate
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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.

Some Recent Findings

Historic drawing of early limb vasculature.

A Comprehensive Study of palate Development in Miniature Pig "palate development is an important morphogenetic event in facial development, including the fusion of the lateral and medial nasal portions of the frontonasal process and maxilla. Derailments of any of these events may result in cleft palate, the most frequent congenital craniofacial abnormality. Recent research has shown that the microanatomy of the miniature pig oral maxillofacial region is quite similar to that of humans, and the use of miniature pigs as a large animal model for dental and orofacial research is increasing. Little information is available, however, about the development of the miniature pig palate. Here, using histological and ultrastructural methods, we describe the developmental stages of the palate in miniature pigs. Sections from E26, E30, E35, E40, E45, and E50 embryos were stained with hematoxylin-eosin, and selected specimens were also processed for electron microscopy. The development of the miniature pig palate can be divided into four stages: growth of the bilateral palatal shelves alongside the tongue at E30; elevation of the horizontal position above the tongue at E35; establishment of bilateral shelf contact at the midline from E35-50; and a final fusion step at E50, similar to the mouse and human. The histological characteristics of the miniature pig palate at different developmental stages were synchronously verified at the ultrastructural level. Our study provides a piece of first-hand data regarding palate morphological organogenesis in the miniature pig and a foundation for further research with this model to explore mechanisms of cleft palate development. Porcine Pluripotent Stem Cells Derived from IVF Embryos Contribute to Chimeric Development In Vivo "Here, we derived a porcine pluripotent stem cell (pPSC) line from day 5.5 blastocysts in a newly developed culture system based on MXV medium and a 5% oxygen atmosphere. The pPSCs had been passaged more than 75 times over two years, and the morphology of the colony was similar to that of human embryonic stem cells." An In Vivo Three-Dimensional Magnetic Resonance Imaging-Based Averaged Brain Collection of the Neonatal Piglet "Due to the fact that morphology and perinatal growth of the piglet brain is similar to humans, use of the piglet as a translational animal model for neurodevelopmental studies is increasing. Magnetic resonance imaging (MRI) can be a powerful tool to study neurodevelopment in piglets, but many of the MRI resources have been produced for adult humans. Here, we present an average in vivo MRI-based atlas specific for the 4-week-old piglet." (More? Neural System - Postnatal) 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."

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: Pig Embryology | Pig Development

Older papers

These papers originally appeared in the Some Recent Findings table, but as that list grew in length have now been shuffled down to this collapsible table. See also the Discussion Page for other references listed by year and References on this current page. 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."

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

Carnegie Stages Comparison Table

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

Table data - Otis and Brent (1954)

Links: Carnegie Stage Comparison

Reproductive Overview

Pig development (day 1 to 10)

• 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.

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.

Spermatozoa

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.

Testis

The testis of the pig receives its first blood supply when the embryo is 33 mm in length.

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.

Palate Development

Plates below are from a 1916 thesis on palate development in the pig.

Fig. 1. Frontal view of the head of the 12 mm. pig embryo. Fig. 2. Ventral view of the roof of the primitive mouth of the 17 mm. embryo. Fig. 3. Ventral view of the roof of the primitive mouth of the 20 mm. embryo. Fig.4. Ventral view of the roof of the primitive mouth of the 25 mm. embryo. Fig. 5. Ventral View of the roof of the primitive mouth of the 27 mm. embryo. Fig. 6. Ventral view of the roof of the secondary mouth of the 50 mm. embryo. Fig. 7. Ventral view of the roof of the secondary mouth of the 39 mm. embryo. Fig. 8. Ventral View of the roof of the secondary mouth of the 70 mm. embryo.

Fig. 9. Cross-section of the head of the 12 mm embryo, slightly oblique, thus showing on one side, the fused processes where mesenchyme has invaded the area, on the other, the bucco-nasal membrane. Fig. 10. Cross-section of the head of the 12 mm. embryo posterior fig. 9, showing the union of the processes on one side and the blind sac on the other. Fig. 11. Cross-section through the head of a 17 mm. embryo showing primitive choanae. Fig. 12. Cross~section through the anterior region of the head of a 27 mm embryo showing the shorter palatal processes. Fig. 13. Cross-section through the head of a 27 mm. embryo posterior to fig. 12, to show the processes longer in this middle region. Fig. 14. Cross-section of the head of the 50 mm. embryo, showing the anterior communication of the nasal and mouth cavities. Fig. 15. Cross-section through the head of the 30 mm. embryo, posterior to fig. 14, to show the fusion of the processes, the slight indication of the invasion of mesemchyme and the fusion of the processes with the nasal septum. Fig. 16. Cross-section through the head of the 30 mm. embryo in the posterior region to show the ventral separation. Fig. 17. Cross-section of the 39 mm. embryo cut slightly oblique, showing on one side the respiratory duct cut off,on the other, the connexion with the respiratory cavity.

Miniature Pig Palate Timeline

1. E30 - growth of the bilateral palatal shelves alongside the tongue
2. E35 - elevation of the horizontal position above the tongue
3. E35-50 - establishment of bilateral shelf contact at the midline
4. E50 - final palate fusion step

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

Buddington RK, Sangild PT, Hance B, Huang EY & Black DD. (2012). Prenatal gastrointestinal development in the pig and responses after preterm birth. J. Anim. Sci. , 90 Suppl 4, 290-8. PMID: 23365359 DOI.

Somfai T, Kikuchi K & Nagai T. (2012). Factors affecting cryopreservation of porcine oocytes. J. Reprod. Dev. , 58, 17-24. PMID: 22450280

Ostrup E, Hyttel P & Ostrup O. (2011). Embryo-maternal communication: signalling before and during placentation in cattle and pig. Reprod. Fertil. Dev. , 23, 964-75. PMID: 22127002 DOI.

Waclawik A. (2011). Novel insights into the mechanisms of pregnancy establishment: regulation of prostaglandin synthesis and signaling in the pig. Reproduction , 142, 389-99. PMID: 21677026 DOI.

Robison OW. (1976). Growth patterns in swine. J. Anim. Sci. , 42, 1024-35. PMID: 770410

Book SA & Bustad LK. (1974). The fetal and neonatal pig in biomedical research. J. Anim. Sci. , 38, 997-1002. PMID: 4596894

Moor RM. (1968). Foetal homeostasis: conceptus-ovary endocrine balance. Proc. R. Soc. Med. , 61, 1217-26. PMID: 4973146

Moor RM. (1968). Effect of embryo on corpus luteum function. J. Anim. Sci. , 27 Suppl 1, 97-118. PMID: 4951167

Articles

Zhang L, Lin Z, Bi Y, Zheng X, Xiao H & Hua Z. (2018). CO2 concentration affects in vitro pig embryo developmental capacity. Pol J Vet Sci , 21, 609-614. PMID: 30468346 DOI.

Liu J, Zhu Y, Luo GZ, Wang X, Yue Y, Wang X, Zong X, Chen K, Yin H, Fu Y, Han D, Wang Y, Chen D & He C. (2016). Abundant DNA 6mA methylation during early embryogenesis of zebrafish and pig. Nat Commun , 7, 13052. PMID: 27713410 DOI.

Hassoun R, Schwartz P, Rath D, Viebahn C & Männer J. (2010). Germ layer differentiation during early hindgut and cloaca formation in rabbit and pig embryos. J. Anat. , 217, 665-78. PMID: 20874819 DOI.

Search PubMed

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. (2023, December 2) Embryology Pig Development. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Pig_Development

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© Dr Mark Hill 2023, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G