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Animals : an open access journal from MDPI2021; 11(8); 2422; doi: 10.3390/ani11082422

Sexual Differentiation and Primordial Germ Cell Distribution in the Early Horse Fetus.

Abstract: It was the aim of this study to characterize the development of the gonads and genital ducts in the equine fetus around the time of sexual differentiation. This included the identification and localization of the primordial germ cell population. Equine fetuses between 45 and 60 days of gestation were evaluated using a combination of micro-computed tomography scanning, immunohistochemistry, and multiplex immunofluorescence. Fetal gonads increased in size 23-fold from 45 to 60 days of gestation, and an even greater increase was observed in the metanephros volume. Signs of mesonephros atrophy were detected during this time. Tubular structures of the fetal testes were present from day 50 onwards, whereas cell clusters dominated in the fetal ovary. The genital ducts were well-differentiated and presented a lumen in all samples. No sign of mesonephric or paramesonephric duct degeneration was detected. Expression of AMH was strong in the fetal testes but absent in ovaries. Irrespective of sex, primordial germ cells selectively expressed LIN28. Migration of primordial germ cells from the mesonephros to the gonad was detected at 45 days, but not at 60 days of development. Their number and distribution within the gonad were influenced ( < 0.05) by fetal sex. Most primordial germ cells (86.8 ± 3.2% in females and 84.6 ± 4.7% in males) were characterized as pluripotent according to co-localization with CD117. However, only a very small percentage of primordial germ cells were proliferating (7.5 ± 1.7% in females and 3.2 ± 1.2% in males) based on co-localization with Ki67. It can be concluded that gonadal sexual differentiation in the horse occurs asynchronously with regard to sex but already before 45 days of gestation.
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Publication Date: 2021-08-17 PubMed ID: 34438878PubMed Central: PMC8388682DOI: 10.3390/ani11082422Google Scholar: Lookup
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  • Journal Article

Summary

This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.

The research study investigates the development of reproductive organs in horse fetuses during the period of sexual differentiation. It especially focuses on the identification and tracking of primordial germ cells, which are the precursors to both sperm and egg cells.

Objective and Methodology

  • The research aimed to understand and document the growth patterns of the gonads, the primary sexual organs, and the genital ducts in horse fetuses in the period surrounding sexual differentiation. Additionally, it sought to identify and track primordial germ cells.
  • Equine fetuses between 45 and 60 days of gestation were studied with a combination of micro-computed tomography scanning, immunohistochemistry, and multiplex immunofluorescence. These techniques allowed the researchers to observe detailed structural changes and detect specific cell types and molecules.

Key Findings

  • The size of the fetal gonads increased 23-fold from 45 to 60 days of gestation. Alongside this growth, the researchers noticed a considerable increase in the metanephros volume, an early stage of the kidney.
  • Signs of mesonephros atrophy, or wasting away of an early stage of kidney development, were identified during this timeframe. This suggests that the formation of the gonads and the metanephros is accompanied by the reduction of the mesonephros structure.
  • Different growth patterns were observed in the testes and ovaries. Tubular structures were present in the testes from day 50 onwards, whereas cell clusters dominated in the ovaries.
  • Genital ducts – the structures that will develop into the tubes that carry sperm or eggs – were well-differentiated and exhibited a lumen, or central cavity, in all samples. The researchers found no sign of degeneration of two types of ducts associated with kidney and reproductive organ development, the mesonephric and paramesonephric ducts.

Primordial Germ Cell Observations

  • Primordial germ cells, the precursors to sperm and egg cells, were tracked using their selective expression of LIN28, a protein associated with cell proliferation and development. Their migration from the mesonephros to the gonad was detected at 45 days, but not at 60 days of development. The distribution and count of these cells in the gonad were found to be influenced by the sex of the fetus.
  • A large majority of primordial germ cells showed signs of pluripotency, having the potential to differentiate into various types of cells, according to their co-localization with CD117, a protein associated with stem cells.
  • A small percentage of these cells were found to be proliferating, or multiplying, based on their co-localization with Ki67, a protein associated with cell division.

Conclusion

  • The research concludes that gonadal sexual differentiation in horses occurs asynchronously with regard to sex and begins before 45 days of gestation.

Cite This Article

APA
Scarlet D, Handschuh S, Reichart U, Podico G, Ellerbrock RE, Demyda-Peyrás S, Canisso IF, Walter I, Aurich C. (2021). Sexual Differentiation and Primordial Germ Cell Distribution in the Early Horse Fetus. Animals (Basel), 11(8), 2422. https://doi.org/10.3390/ani11082422

Publication

Animals : an open access journal from MDPI
ISSN: 2076-2615
NlmUniqueID: 101635614
Country: Switzerland
Language: English
Volume: 11
Issue: 8
PII: 2422

Researcher Affiliations

Scarlet, Dragos
  • Obstetrics, Gynecology and Andrology, Department for Small Animals and Horses, University of Veterinary Medicine Vienna, Veterinärplatz 1, 1210 Vienna, Austria.
  • Institute of Veterinary Anatomy and Clinic of Reproductive Medicine, Vetsuisse Faculty Zürich, Winterthurerstrasse 260, 8057 Zürich, Switzerland.
Handschuh, Stephan
  • Vetcore Facility for Research, University of Veterinary Medicine Vienna, Veterinärplatz 1, 1210 Vienna, Austria.
Reichart, Ursula
  • Vetcore Facility for Research, University of Veterinary Medicine Vienna, Veterinärplatz 1, 1210 Vienna, Austria.
Podico, Giorgia
  • Department of Veterinary Clinical Medicine, College of Veterinary Medicine, University of Illinois Urbana-Champaign, Urbana, IL 61802, USA.
  • Department of Comparative Biosciences, College of Veterinary Medicine, University of Illinois Urbana-Champaign, Urbana, IL 61802, USA.
Ellerbrock, Robyn E
  • Department of Veterinary Clinical Medicine, College of Veterinary Medicine, University of Illinois Urbana-Champaign, Urbana, IL 61802, USA.
  • Department of Comparative Biosciences, College of Veterinary Medicine, University of Illinois Urbana-Champaign, Urbana, IL 61802, USA.
Demyda-Peyrás, Sebastián
  • Department of Animal Production, School of Veterinary Sciences, National University of La Plata and CONICET CCT-La Plata, Calle 60 and 118 S/N, 1900 La Plata, Argentina.
Canisso, Igor F
  • Department of Veterinary Clinical Medicine, College of Veterinary Medicine, University of Illinois Urbana-Champaign, Urbana, IL 61802, USA.
  • Department of Comparative Biosciences, College of Veterinary Medicine, University of Illinois Urbana-Champaign, Urbana, IL 61802, USA.
Walter, Ingrid
  • Vetcore Facility for Research, University of Veterinary Medicine Vienna, Veterinärplatz 1, 1210 Vienna, Austria.
  • Institute of Pathology, Department of Pathobiology, University of Veterinary Medicine Vienna, Veterinärplatz 1, 1210 Vienna, Austria.
Aurich, Christine
  • Center for Artificial Insemination and Embryo Transfer, University of Veterinary Medicine Vienna, Veterinärplatz 1, 1210 Vienna, Austria.

Conflict of Interest Statement

The authors declare no conflict of interest.

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