Staging of porcine embryos: Comparison of Standard Event System‐based statistical clusters with a Carnegie‐based staging system

Abstract

Background: Methods to compare events defined as newly occurring characters in development has advanced vertebrate developmental research but events are not easily extrapolated into traditional staging systems used in biomedical research. Results: First, we scored 95 porcine embryos in the age range of 15 to 33 days post conception by stereomicroscopy using to a slightly modified version of the Standard Event System (SES). Subsequent statistical clustering allowed the embryos to be grouped into 15 clusters. Staging of the same embryos in a way that generally follow the description of external features of human embryos in the Carnegie stages 10 to 23 allowed us to describe 14 stages of porcine embryonic development that correlate to the Carnegie stages of human development with minor species differences. When arranged by average age, the statistic clusters had a distribution that correlated well with the stages produced by the Carnegie-based staging system. Conclusions: Statistical analysis of developmental events allow grouping of porcine embryos into clusters that can be extrapolated into a Carnegie-based staging system, thus serving the dual purpose of facilitating the use of the pig as a biomedical model animal and providing data for integrating porcine developmental events into a phylogenetic context.

Efficient derivation of transgene-free porcine induced pluripotent stem cells enables in vitro modeling of species-specific developmental timing

“…We chose to focus on the temporal pattern of somitogenesis between stage 10 (16 dpi, ∼4–12 somites) and 13 (19.5 dpi, ∼30 somites) and estimated the porcine-specific somite budding to be 3.2–4.6 h/somite pair ( Figure S3 C). This is intermediate and notably different from the estimated mouse (∼2 h) and human (∼4–8 h) somite budding based on the staging data ( Graham et al., 2015 ; Mogeltoft Kamstrup et al., 2020 ; O'Rahilly, 1979 ).…”

“…In addition, overexpression of human NOTCH intracellular domain (hNICD) cDNA abolishes the pig clock gene oscillation ( Figure S3 I), likely because of the disruption of the NOTCH signaling negative feedback loops ( Hubaud and Pourquie, 2014 ; Oates et al., 2012 ). Thus, while the in vitro porcine segmentation clock model is regulated by conserved signaling pathways similar to the human clock, it displays pig-specific ∼3.7-h periodicity, which recapitulates the rate of somitogenesis estimated from the embryonic staging data ( Hubaud and Pourquie, 2014 ; Mogeltoft Kamstrup et al., 2020 ; Muller and O'Rahilly, 1986 ; Sparrow et al., 2007 ) ( Figure S3 C).

Figure 3 Comparative characterizations of porcine and human segmentation clock models in vitro (A) Immunofluorescence assay of undifferentiated and PSM cells derived from a clonal PiPSC line (top) or hESCs (H1 hESC, bottom), co-stained with NANOG, TBX6, and Hoechst 33342.

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“…We, therefore, wanted to test if a pig-specific clock time could be observed in vitro , a phenotype known as developmental allochrony ( Matsuda et al., 2020a ; Rayon and Briscoe, 2021 ; Rayon et al., 2020 ). Early porcine embryonic development is well studied and thus provides an excellent in vivo reference ( Mogeltoft Kamstrup et al., 2020 ). We first curated embryonic staging data to compare porcine and human embryos side by side ( Figures S3 A–S3C).…”

Morphological research on amniote eggs and embryos: An introduction and historical retrospective

“…Nevertheless, many have been published in recent years. Among them are staging systems for embryos of bats (Cretekos et al, 2005;Tokita, 2006), cetaceans (Štěrba et al, 2012), pigs (Kamstrup et al, 2020), humans (O'Rahilly & Müller, 2010), tenrecs (Werneburg et al, 2013), and rodents (Downs & Davies, 1993), as well as a variety of other mammalian species (Butler & Juurlink, 2018;Štěrba, 1995).…”